Water-Cooled Scroll Compressor Chillers

Operating Manual
OM WGZC-1
Group: Chiller
Part Number: 331975301
Effective: June 2009
Supercedes: OM WGZC
Water-Cooled Scroll Compressor Chillers
WGZ 030CW To WGZ 200CW, Packaged Water-Cooled Chiller
WGZ 030CA To WGZ 200CA, Chiller with Remote Condenser
30 to 200 Tons, 105 to 700 kW
Software Version WGZD20102E
Table of Contents
Introduction ....................................... 3
General Description .............................. 3
Nomenclature ........................................ 3
Water Pressure Drop ............................. 3
Operating Limits ................................... 6
Components .......................................... 6
Automatic Adjusted Limits ................. 24
Dynamic Defaults ............................... 25
Events & Alarms ............................. 25
Unit Stop Alarms................................. 25
Limit Events........................................ 30
Controller Operation ...................... 33
Unit Configuration ............................ 7
EXV Control ....................................... 54
Field Wiring Diagrams.......................... 8
Control Panel Layout .......................... 10
Motor Protection Module.................... 10
Using the Controller........................ 55
Start-Up and Shutdown .................. 11
Sequence of Operation .................... 14
Start-up/Compressor Staging .............. 14
MicroTech II Controller.................. 18
Controller Software Version ............... 18
General Description ............................ 18
Expansion I/O Controller .................... 21
Setpoints.............................................. 22
Menu Screens...................................... 57
Menu Descriptions .............................. 58
BAS Interface...................................... 77
Optional Controls............................ 79
Phase/Voltage Monitor (Optional) ...... 79
Hot Gas Bypass (Optional) ................. 79
Troubleshooting Chart ........................ 80
Warranty Statement........................ 81
Manufactured in an ISO Certified facility
©2007 McQuay International. Illustrations and data cover the McQuay International product at the time of publication and we
reserve the right to make changes in design and construction at anytime without notice. ™® The following are trademarks or
registered trademarks of their respective companies: BACnet from ASHRAE; LONMARK, LonTalk, LONWORKS, and the
LONMARK logo are managed, granted and used by LONMARK International under a license granted by Echelon Corporation;
Compliant Scroll from Copeland Corporation; Modbus from Schneider Electric; FanTrol, MicroTech II, Open Choices, and
SpeedTrol from McQuay International
2
OM WGZC-1
Introduction
General Description
McQuay Type WGZ water chillers are designed for indoor installations and are available with
water-cooled condensers (Model CW), or arranged for use with remote air-cooled or evaporative
condensers (Model CA). Each water-cooled unit is completely assembled and factory wired
before evacuation, charging and testing. They consist of hermetic scroll compressors, brazed-plate
evaporator, water-cooled condenser (WGZ-CW), and complete refrigerant piping.
Units manufactured for use with remote condensers (Models WGZ-CA) have all refrigerant
specialties factory-mounted and connection points for refrigerant discharge and liquid lines.
Liquid line components that are included are manual liquid line shutoff valves, charging valves,
filter-driers, liquid line solenoid valves, sight glass/moisture indicators, and thermal expansion
valves. Other features include compressor crankcase heaters, and a MicroTech II microprocessor
controller.
The electrical control center includes all equipment protection and operating controls necessary
for dependable automatic operation.
NOTE: This manual contains information on the chiller unit control software operating with
various refrigerant as follows:
•
R-410A, used with the current “C” vintage of the WGZ chiller.
•
R-22 and R-407C, used with older “A” and “B:” vintage chillers. A replacement controller in
one of these units would be loaded with this software version.
•
R-134a, used with only with Model TGZ Templfiers.
exclusively to Templifiers is OMM TGZ-1.
The operating manual devoted
BOOT & BIOS
BOOT Version: 3.0F
BIOS Version 3.56
Manuals: Information in unit initial installation and routine maintenance is contained in
Installation and Maintenance Manual IMM WGZC.
Nomenclature
W G Z 100 - C W
Water-Cooled
Global
Scroll Compressor
Water Pressure Drop
W = Water-Cooled Cond.
A = Unit Less Cond.
Design Vintage
Nominal Capacity (Tons)
Water flow rates should be maintained as closely as possible to job design values. The vessel
flow rates must fall between the minimum and maximum values shown on the appropriate
evaporator and condenser curves.
Measure the water pressure drop through the vessels at field-installed pressure taps and check the
flow rate using the following tables. Do not include valves or strainers in these readings.
The evaporator flow rates and pressure drops shown on the following page are for full load
design purposes. The maximum flow rate and pressure drop are based on a 6-degree temperature
drop. Avoid higher flow rates with resulting lower temperature drops to prevent potential control
problems resulting from very small control bands and limited start up/shut off temperature
changes.
The minimum flow and pressure drop is based on a full load evaporator temperature drop of 16degrees.
OM WGZC-1
3
Pressure Drop (ft of water)
Figure 1, Evaporator Pressure Drop, WGZ 030C – WGZ 200C
Flow Rate (GPM)
Minimum Flow
WGZ-C
Model
Ref
#
Inch-Pound
GPM
Ft.
Nominal Flow
S.I.
L/S
Inch-Pound
kPa
GPM
Maximum Flow
S.I.
Inch-Pound
Ft.
L/S
kPa
S.I.
GPM
Ft.
L/S
kPa
82.4
WGZ030C
A
45
4.7
2.8
14.1
72
11
4.5
32.9
120
27.6
7.6
WGZ035C
B
51.9
4.9
3.3
14.6
83
11.4
5.2
34
138.3
28.5
8.7
85.4
WGZ040C
C
61.1
5.1
3.9
15.2
97.8
11.8
6.2
35.4
163
29.7
10.3
88.8
WGZ045C
D
68.2
5.2
4.3
15.5
109.1
12.1
6.9
36.1
181.8
30.2
11.5
90.4
WGZ050C
E
76.7
5.8
4.8
17.2
122.6
13.4
7.7
40.1
204.4
33.6
12.9
100.6
WGZ055C
F
84.6
6.1
5.3
18.1
135.4
14.1
8.5
42.2
225.6
35.4
14.2
105.9
WGZ060C
G
90.8
6.6
5.7
19.7
145.2
15.6
9.2
46.5
242
39.2
15.3
117.1
WGZ070C
H
106.3
3.7
6.7
10.9
170
8.6
10.7
25.6
283.4
21.2
17.9
63.3
WGZ080C
I
117.5
4.3
7.4
12.8
187.9
10
11.9
29.9
313.2
25
19.8
74.9
WGZ090C
J
132.1
4.5
8.3
13.3
211.3
10.5
13.3
31.3
352.1
26.1
22.2
78.1
WGZ100C
K
146.6
4.9
9.3
14.6
234.6
11.4
14.8
34.1
391.1
28.7
24.7
85.8
WGZ115C
L
169.3
4.5
10.7
13.5
270.9
10.5
17.1
31.4
451.5
26.4
28.5
78.9
WGZ130C
M
188.1
4.2
11.9
12.6
301
9.8
19
29.5
501.6
24.7
31.6
73.9
WGZ150C
N
219.9
5
13.9
14.9
351.8
12.8
22.2
38.3
586.4
35.5
37
106.1
WGZ170C
O
254
7.2
16
21.5
406.3
18.5
25.6
55.3
677.2
51.4
42.7
153.6
WGZ200C
P
282.2
8.6
17.8
25.7
451.4
22
28.5
65.8
752.4
61
47.5
182.3
Notes: Minimum, nominal, and maximum flows are at a 16º F, 10º F, and 6º F chilled water temperature range respectively at ARI tons.
4
OM WGZC-1
Pressure Drop (ft of water)
Figure 2, Condenser Pressure Drop, WGZ 030C – WGZ 200C
Flow Rate (GPM)
Unit Model
Min. Flow & PD
Ref
#
IP
Nom. Flow & PD
SI
IP
GPM
SI
Ft.
L/S
IP
kPa
GPM
SI
GPM
Ft.
L/S
WGZ030C
A
56.1
2.4
3.5
7.2
89.7
6.3
5.7
18.8
149.5
17.4
9.4
52.0
WGZ035C
B
64.9
3.4
4.1
10.2
103.8
8.6
6.5
25.7
173.0
23.9
10.9
71.4
WGZ040C
C
76.3
2.7
4.8
8.1
122.1
6.9
7.7
20.6
203.5
19.3
12.8
57.7
WGZ045C
D
85.3
3.6
5.4
10.8
136.5
9.2
8.6
27.5
227.5
25.7
14.4
76.8
WGZ050C
E
96.4
2.9
6.1
8.7
154.2
7.5
9.7
22.4
257.0
20.7
16.2
61.9
WGZ055C
F
105.8
3.8
6.7
11.4
169.2
9.7
10.7
29.0
282.0
26.8
17.8
80.1
WGZ060C
G
113.4
4.5
7.2
13.5
181.5
11.6
11.5
34.7
302.5
32.3
19.1
96.5
WGZ070C
H
132.8
4.1
8.4
12.3
212.4
10.4
13.4
31.1
354.0
29.0
22.3
86.7
WGZ080C
I
146.8
3.7
9.3
11.1
234.9
9.5
14.8
28.4
391.5
26.5
24.7
79.2
WGZ090C
J
165.0
3.4
10.4
10.2
264
8.8
16.7
26.3
440.0
24.5
27.8
73.2
WGZ100C
K
183.4
3.4
11.6
10.2
293.4
8.8
18.5
26.3
489.0
24.4
30.9
72.9
WGZ115C
L
211.7
4.8
13.4
14.3
338.7
12.3
21.4
36.8
564.5
34.1
35.6
101.9
WGZ130C
M
235.1
6.1
14.8
18.2
376.2
15.5
23.7
46.3
627.0
43.1
39.6
128.8
WGZ150C
N
274.9
6.2
17.3
18.5
439.8
15.8
27.7
47.2
733.0
43.8
46.2
130.9
WGZ170C
O
317.4
5.5
20.0
16.4
507.9
14.0
32.0
41.8
846.5
38.9
53.4
116.3
WGZ200C
P
352.7
7.4
22.3
22.1
564.3
18.8
35.6
56.2
940.5
52.3
59.3
156.3
OM WGZC-1
kPa
Max. Flow & PD
Ft.
L/S
kPa
5
Operating Limits
•
•
•
•
•
•
Maximum allowable condenser water pressure is 232 psig (1599 kPa).
Maximum allowable cooler water pressure is 653 psi (4500 kPa) for models 030
through 130 and 150 psig (2509 kPa) for models 150 through 200.
Maximum design saturated discharge temperature is 140°F (60°C).
Maximum allowable water temperature to cooler in a non-operating cycle is 100°F
(37.8°C). Maximum entering water temperature for operating cycle is 90°F
(32.2°C) (during system changeover from heating to cooling cycle).
Minimum leaving water temperature from the cooler without freeze protection is
40°F (4.4°C).
Minimum entering tower condenser water temperature is 60°F (15.6°C).
Components
Figure 3, Compressor Locations
4
2
Circuit 2
3
Evaporator
1
Circuit 1
Evaporator and
Condenser
Connections
Control Panel
NOTE: Models WGZ 150 to 200 add a #5 compressor to circuit #1 and a #6
compressor to circuit #2.
Table 1, Major Components
Comp. #1
Comp. #3
Comp. #2
Comp. #4
Evap.
Vessel
Size
30
ZP90KCE
ZP90KCE
ZP90KCE
ZP90KCE
ACH130-90DQ
C1010-47
OZE-20-GA-BP15 OZE-20-GA-BP15
35
ZP103KCE ZP103KCE ZP103KCE ZP103KCE ACH130-102DQ
C1010-47
OZE-20-GA-BP15 OZE-20-GA-BP15
40
ZP120KCE ZP120KCE ZP120KCE ZP120KCE
ACH130118DQ
C1010-57
OZE-20-GA-BP15 OZE-20-GA-BP15
45
ZP137KCE ZP137KCE ZP137KCE ZP137KCE ACH130-138DQ
C1010-57
OZE-25-GA-BP15 OZE-25-GA-BP15
50
ZP154KCE ZP154KCE ZP154KCE ZP154KCE ACH130-158DQ
C1010-70
OZE-25-GA-BP15 OZE-25-GA-BP15
55
ZP154KCE ZP154KCE ZP182KCE ZP182KCE ACH130-178DQ
C1010-70
OZE-25-GA-BP15 OZE-35-GA-BP15
60
ZP182KCE ZP182KCE ZP182KCE ZP182KCE ACH130-198DQ
C1010-70
OZE-35-GA-BP15 OZE-35-GA-BP15
70
ZP182KCE ZP235KCE ZP182KCE ZP235KCE ACH250-122DQ
C1410-88
OZE-35-GA-BP15 OZE-35-GA-BP15
80
ZP235KCE ZP235KCE ZP235KCE ZP235KCE ACH350-126DQ
C1410-98
OZE-50-GA-BP15 OZE-50-GA-BP15
WGZ-C
Unit
Size
6
System #1
System #2
Cond.
Vessel
Size
Expansion Valve
System #1
System #2
90
ZP235KCE ZP235KCE ZP295KCE ZP295KCE ACH350-142DQ
C1410-113 OZE-50-GA-BP15 OZE-50-GA-BP15
100
ZP295KCE ZP295KCE ZP295KCE ZP295KCE ACH350-152DQ
C1410-128 OZE-50-GA-BP15 OZE-50-GA-BP15
115
ZP295KCE ZP385KCE ZP295KCE ZP385KCE ACH350-182DQ
C1410-128 OZE-60-GA-BP15 OZE-60-GA-BP15
130
ZP385KCE ZP385KCE ZP385KCE ZP385KCE ACH350-210DQ
C1410-128 OZE-60-GA-BP15 OZE-60-GA-BP15
150
(3) ZP295KCE
(3) ZP295KCE
EV34191111/9NS C1612-156
SEHI100-30-S
SEHI100-30-S
170
(3) ZP295KCE
(3) ZP385KCE
EV34191212/7NS C1612-186
SEHI100-30-S
SEHI100-30-S
200
(3) ZP385KCE
(3) ZP385KCE
EV34191212/7NS C1612-186
SEHI100-30-S
SEHI100-30-S
OM WGZC-1
Unit Configuration
The chiller units have two refrigerant circuits, Models 030 to 130 have two tandem
scroll compressors (total of four), a single two-circuited brazed plate evaporator, a
single two-circuited water-cooled condenser, interconnecting refrigerant piping and a
control panel with associated sensors and transducers.
Models 150 to 200 have two refrigerant circuits, two trio scroll compressors (total of
six), a single two-circuited shell-and-tube evaporator, a single two-circuited watercooled condenser, interconnecting refrigerant piping and a control panel with
associated sensors and transducers.
Figure 4, Schematic Piping Diagram (One of Two Circuits)
T
P
P1
Evaporator
Chilled
Water
S
LWT
Comp
#1
Comp
#2
CV
Condenser
Water
Condenser
T
S
S
S
F-D
Legend:
T
Temperature Sensor
P
T
Pressure Transducer
P1
Pressure (High Pressure Cutout)
Thermal Expansion Valve
Temperataure Sensor, Leaving
Chilled Water Control
Sight Glass / Moisture Indicator
LWT
Relief Valve
S
T
CV
Schrader Fitting
Charging Valve
S
Solenoid Valve
F-D
Filter-Drier
Angle Valve
Ball Valve
NOTE: WGZ 150 to 200 have a shell-and-tube evaporator, three compressors per
circuit, and electronic expansion valves.
OM WGZC-1
7
Field Wiring Diagrams
Figure 5, WGZ 030CW – 300CW Field Wiring Diagram
DISCONNECT
(BY OTHERS)
UNIT MAIN
TERMINAL BLOCK
GND LUG
3 PHASE
POWER
SUPPLY
TO COMPRESSOR(S)
FUSED CONTROL
CIRCUIT
TRANSFORMER
120 VAC
DISCONNECT
(BY OTHERS)
FIELD
SUPPLIED
OPTION
N
TB1-20
10A
FUSE
120VAC
CONTROL POWER
TB1
1
(BY OTHERS)
2
CONTROL
CIRCUIT
FUSE
120 VAC
11
N
14
CHW PUMP RELAY
(BY OTHERS)
120 VAC 1.0 AMP MAX
CONTROLLER
120 VAC
CDW PUMP RELAY
(BY OTHERS)
120 VAC 1.0 AMP MAX
J15-N08
N
TB1-12
120 VAC
J16-N09
TOWER FAN #1 COIL
(BY OTHERS)
120 VAC 1.0 AMP MAX
N
TB1-12
120 VAC
J16-N10
FACTORY SUPPLIED ALARM
FIELD WIRED
TOWER FAN #2 COIL
(BY OTHERS)
120 VAC 1.0 AMP MAX
ALARM BELL ALARM BELL
OPTION
RELAY
120VAC
10
15
REMOTE STOP SWITCH
(BY OTHERS)
ICE MODE SWITCH
(BY OTHERS)
TIME
OFF
CLOCK AUTO
ON
40
MANUAL
OFF
AUTO
ON
CDW FLOW SWITCH
--MANDATORY-(BY OTHERS)
53
42
MANUAL
CHW FLOW SWITCH
--MANDATORY-(BY OTHERS)
GND
TB2
900
55
IF ICE MODE IS USED
REMOVE LEAD
FROM TERM 42 TO 55.
NOR. OPEN PUMP AUX.
CONTACTS (OPTIONAL)
33
43
CONTROLLER
NOR. OPEN PUMP AUX.
CONTACTS (OPTIONAL)
J11
41
53
4-20 MA FOR
CHW RESET
(BY OTHERS)
IF REMOTE STOP CONTROL
897 IS USED, REMOVE LEAD 897
FROM TERM 40 TO 53.
Rx-/Tx-
1
Rx+/Tx+
2
GND
3
38
* COMMUNICATION
PORT
48
49
4-20 MA FOR
DEMAND LIMIT
(BY OTHERS)
38
GND
50
51
GND
8
330258901-R4
OM WGZC-1
Figure 6, WGZ 030CA – 200CA Field Wiring Diagram (Remote Condenser)
UNIT MAIN
DISCONNECT
(BY OTHERS) TERMINAL BLOCK
GND LUG
3 PHASE
POWER
SUPPLY
TO COMPRESSOR(S)
FUSED CONTROL
CIRCUIT
TRANSFORMER
DISCONNECT
(BY OTHERS)
FIELD
SUPPLIED
OPTION
120
VAC
TB1-20
N
120VAC
CONTROL POWER
10A
FUSE
TB1
1
(BY OTHERS)
CONTROL
CIRCUIT
FUSE
2
120 VAC
11
FACTORY SUPPLIED ALARM CHW PUMP RELAY
(BY OTHERS)
FIELD WIRED
120 VAC 1.0 AMP MAX
ALARM BELL
OPTION
ALARM BELL RELAY
REMOTE STOP SWITCH
(BY OTHERS)
ICE MODE SWITCH
(BY OTHERS)
N
14
120VAC
10
15
TIME
OFF
CLOCKAUTO
ON
TB2
40
MANUAL
53
OFF
AUTO
ON
42
MANUAL
55
CHW FLOW SWITCH --MANDATORY-(BY OTHERS)
NOR. OPEN PUMP AUX.
CONTACTS (OPTIONAL)
GND
IF REMOTE STOP CONTROL
897 IS USED, REMOVE LEAD 897
FROM TERM 40 TO 53.
IF ICE MODE IS USED
900 REMOVE LEAD
FROM TERM 42 TO 55.
CONTROLLER
J11
1
Rx-/Tx-
33
43
4-20 MA FOR
CHW RESET
(BY OTHERS)
Rx+/Tx+
GND
38
2
* COMMUNICATION
PORT
3
48
49
4-20 MA FOR
DEMAND LIMIT
(BY OTHERS)
38
GND
50
51
TB3
GND
24 VAC
62
LIQUID LINE #1 SOLENOID
24 VAC AMP MAX
65
63
LIQUID LINE #2 SOLENOID
24 VAC AMP MAX
65
67
OPTIONAL
HOT GAS BYPASS #1 SOLENOID
24 VAC AMP MAX
70
N
24 VAC
N
24 VAC
N
24 VAC
68
HOT GAS BYPASS #2 SOLENOID
24 VAC AMP MAX
70
N
CONTROLLER
120 VAC
J15-N08
FAN MOTOR #1 COIL (BY OTHERS)
120 VAC 1.0 AMP MAX
N
TB1-12
120 VAC
J16-N09
FAN MOTOR #2 COIL (BY OTHERS)
120 VAC 1.0 AMP MAX
120 VAC
J16-N010
FAN MOTOR #3 COIL (BY OTHERS)
120 VAC 1.0 AMP MAX
120 VAC
J16-N011
FAN MOTOR #4 COIL (BY OTHERS)
120 VAC 1.0 AMP MAX
120 VAC
J18-N013
NOTE:
CONDENSER FAN MOTORS
CAN ALSO BE CONTROLLED
BY PRESSURE SWITCHES
ON THE CONDENSER.
FAN MOTOR #5 COIL (BY OTHERS)
120 VAC 1.0 AMP MAX
120 VAC
J22-N016
FAN MOTOR #6 COIL (BY OTHERS)
120 VAC 1.0 AMP MAX
120 VAC
J22-N017
FAN MOTOR #7 COIL (BY OTHERS)
120 VAC 1.0 AMP MAX
120 VAC
J22-N018
330259001-R4
OM WGZC-1
FAN MOTOR #8 COIL (BY OTHERS)
120 VAC 1.0 AMP MAX
9
Control Panel Layout
Table 2, Typical Control Panel, 4-Compressor Unit
Microtech
Controller
(2) Circuit
Mechanical
Hi-Pressure
Switch Relays
(4) Compressor
Circuit Breakers
(4) Compressor
Contactors
Location for
Optional External
Overloads
(3) 120V/24V
Transformers
LineV/120V
Control
Transformer
Control
Transformer
Fuses, Primary
Control
Transformer
Fuse, Secondary
Optional
Disconnect
Switch
Grounding
Lug
NOTES:
1. Additional space provided in the upper right section for extra components required
for optional multiple point power connection and optional circuit breakers.
2. Front door has opening on top for access to the MicroTech II controller for viewing
display and making keypad entries without opening the panel door.
Motor Protection Module
The motor protection system consists of an external control module, located on each
compressor, connected to a series of thermistors located in the motor windings and the
compressor discharge port. If the windings experience an over-temperature condition
or the discharge temperature is excessive, the module will trip and shut off the
compressor for a 30-minute time delay.
10
OM WGZC-1
Start-Up and Shutdown
Pre Start-up
1. The chilled-water system should be flushed and cleaned. Proper water treatment is
required to prevent corrosion and organic growth.
2. With main disconnect open, check all electrical connections in control panel and
starter to be sure they are tight and provide good electrical contact. Although
connections are tightened at the factory, they can loosen enough in shipment to
cause a malfunction.
3. Check and inspect all water piping. Make sure flow direction is correct and piping
is made to correct connection on evaporator and condenser.
4. Open all water flow valves to the condenser and evaporator.
5. Flush the cooling tower and system piping to be sure the system is clean. Start
evaporator pump and manually start condenser pump and cooling tower. Check all
piping for leaks. Vent the air from the evaporator and condenser water circuit, as
well as from the entire water system. The cooler circuit should contain clean,
treated, non-corrosive water.
6. Check to see that the evaporator water thermostat sensor is securely installed.
7. Making sure control stop switch S1 is open (off) and pumpdown switches PS1 and
PS2 are on “manual pumpdown,” place the main power and control disconnect
switches to “on.” This will energize the crankcase heaters. Wait a minimum of 12
hours before starting the unit.
8. Check compressor oil level. Prior to start-up, the oil level should cover at least
one-third of the oil sight glass located in the equalizing line between the
compressors or on the compressor.
9. Note the water pressure drop across evaporator and condenser on pages Error!
Bookmark not defined. and Error! Bookmark not defined. and check that water
flow is correct per the system design flow rates.
10. Check the actual line voltage to the unit to make sure it is the same as called for on
the compressor nameplate, within + 10%, and that phase voltage unbalance does
not exceed 3%. Verify that adequate power supply and capacity is available to
handle load.
11. Make sure all wiring and fuses are of the proper size. Also make sure that all
interlock wiring is completed per McQuay diagrams.
12. Verify that all mechanical and electrical inspections by code authorities have been
completed.
13. Make sure all auxiliary load and control equipment is operative and that an
adequate cooling load is available for initial start-up.
Start-up
1. Open the compressor discharge shutoff valves until backseated. Always replace
valve seal caps.
2. Open the two manual liquid line shutoff valves.
3. Check to see that the unit circuit breakers are in the “off” position.
4. Check to see that the pumpdown switches, PS1 and PS2, are in the “manual
pumpdown” position and the control system switch S1 is in the “off” position.
OM WGZC-1
11
5. Put the main power and control circuit disconnects to the “on” position.
6. Verify crankcase heaters have operated for at least 12 hours prior to start-up.
Crankcase should be warm to the touch.
7. Check that the MicroTech II controller is set to the desired chilled water
temperature.
8. Start the system auxiliary equipment for the installation by turning on the time
clock, ambient thermostat and/or remote on/off switch and water pumps.
9. Check resets of all equipment protection controls.
10. Switch on the unit circuit breakers.
11. Set pumpdown switches PS1 and PS2 to “auto” for restart and normal operation.
12. Start the system by setting the system switch S1 to on.
13. After running the unit for a short time, check the oil level in each compressor
crankcase, rotation of condenser fans (if any), and check for flashing in the
refrigerant sight glass.
14. After system performance has stabilized, it is necessary that the “Compressorized
Equipment Warranty Form” (Form No. 206036A) be completed to establish
commencement of the warranty period. Be sure to list the pressure drop across
both vessels. This form is shipped with the unit and after completion should be
returned to the McQuayService Department through your sales representative.
Weekend or Temporary Shutdown
Move pumpdown switches PS1 and PS2 to the “manual pumpdown” position. After the
compressors have pumped down, turn off the chilled water pump. Note: With the unit
in this condition, it will not restart until these switches are turned back on. The unit
has one-time pumpdown. It is important that the compressors pump down before the
water flow to the unit is interrupted to avoid freeze-up in the evaporator.
Leave S1 on and power to the unit so that the crankcase heaters will remain energized.
Start-up after Temporary Shutdown
1. Start the water pumps.
2. With the control system switch S1 in the “on” position, move the pumpdown
switches PS1 and PS2 to the “auto pumpdown” position.
3. Observe the unit operation for a short time, noting unusual sounds or possible
cycling of compressors.
4. Check compressor crankcase heaters.
Extended Shutdown
Close the manual liquid line shutoff valves.
After the compressors have pumped down, turn off the water pumps.
Turn off all power to the unit.
Move the control service switch S1 to the “off” position.
Close the discharge shutoff valves on the compressor(s) and the liquid outlet valves
at the condenser.
Tag all opened disconnect switches to warn against start-up before opening the
compressor suction and discharge valves.
Drain all water from the unit evaporator, condenser, and chilled water piping if the
unit is to be shut down during the winter and exposed to below freezing
temperatures. Do not leave the vessels or piping open to the atmosphere over the
shutdown period.
12
OM WGZC-1
Start-up after Extended Shutdown
1. Inspect all equipment to see that it is in satisfactory operating condition.
2. Remove all debris that has collected on the surface of the condenser coils (remote
condenser models) or check the cooling tower, if present.
3. Backseat the compressor discharge valves. Always replace valve seal caps.
4. Open the manual liquid line shutoff valves.
5. Check circuit breakers. They must be in the “off” position.
6. Check to see that the pumpdown switches PS1 and PS2 are in the “manual
shutdown” position and the control system switch S1 is in the “off” position.
7. Put the main power and control circuit disconnects to the “on” position.
8. Allow the crankcase heaters to operate for at least 12 hours prior to start-up.
9. Start the chilled water pump and purge the water piping as well as the evaporator in
the unit.
10. Start the system auxiliary equipment for the installation by turning on the time
clock, ambient thermostat and/or remote on/off switch.
11. Check that the MicroTech II controller is set to the desired chilled water temperature.
12. Check resets of all equipment protection controls.
13. Switch the unit circuit breakers to “on.”
14. Start the system by setting the system switch S1 to “on.”
!
CAUTION
Most relays and terminals in the control center are powered when S1 is closed and the
control circuit disconnect is on. Therefore, do not close S1 until ready for start-up or
serious equipment damage can occur.
15. Set pumpdown switches PS1 and PS2 to the “auto pumpdown” position for restart
and normal operation.
16. After running the unit for a short time, check the oil level in the compressor oil
sight glass or in the compressor’s equalizing lines for flashing, indicating possible
refrigerant in the oil.
Low Ambient Start
The low ambient start logic is for starting units with remote air-cooled condensers
during periods of low ambient air temperatures.
A low ambient start takes place if the saturated condenser temperature is less than
85.0°F when the first compressor starts. The low ambient start is active for a time
defined by the Low OAT Start Timer set point. This set point is found on screen three
in the alarm set points menus.
During the low ambient start, the freezestat logic for the low-pressure stop alarm and
the low-pressure events are disabled. The low-pressure stop alarm can still be triggered
if the evaporator pressure drops below 5.0 psi at any time while the circuit is in the
‘Run’ state. Also, during the low ambient start, the second compressor is not allowed to
start. The evaporator pressure is checked at the end of the low ambient start time
frame. If the pressure is less than the Low Pressure Unload set point, then the low
ambient start is not successful and the compressor will shut off. This will not be a
manual reset alarm until three consecutive attempts have failed. The circuit alarm
triggered after the third failed attempt is a Low OAT Restart fault. The Low OAT
Restart faults are Circuit alarms so each circuit will attempt to start either compressor
three times before the Low OAT Restart fault is indicated.
OM WGZC-1
13
Fan High Ambient Rapid Start
The following logic exists to get condenser fans started earlier than normal during unit
starts with warm ambient air temperatures.
•
•
•
If the outside air temperature higher than 75.0°F the condenser fan staging logic
changes to bring on the first fan on when the condenser pressure is greater than 140
psi.
The standard condenser fan staging logic would start the first condenser fan when
the condenser pressure is higher than 200.0 psi.
The last condenser fan on each circuit will not shut down until the condenser
pressure drops below 140.0 psi regardless of the outside air temperature
Sequence of Operation
The following sequence of operation is typical for WGZ water chiller models. The
sequence can vary slightly depending upon options.
Compressor Heaters
With the control circuit power on and the control stop switch S1 off, 115V power is
applied through the control circuit fuse Fl to the compressor crankcase heaters HTR1,
HTR2, HTR3, and HTR4.
Start-up/Compressor Staging
When compressors start and stop.
Stage Up Temp is the LWT temperature at which the next compressor to start will
stage up (start) after at least one compressor on the unit has started and is running.
Start Up Temp is the LWT at which the first compressor starts. The start up
temperature equals the stage up temperature plus the Start Delta temperature. A high
Start Delta will keep the unit off longer and reduce unit cycling at low loads. However,
this high Start Delta will cause a larger excursion from the LWT setpoint before the
unit starts.
Stated another way, the Start Delta is the number of degrees above the Evap LWT
setpoint, plus ½ the Dead Band, that determines when the first compressor starts. The
Start Delta is in effect for only the first start after all compressors have been off.
Additional compressor starts and stops are determined by the LWT in respect to the
dead band only. The dead band is automatically set of 30% of the EvapDeltaT selected
in menu 3. The following sequence would occur for the settings shown below:
EvapDelta T=10.0°F
LWT=40.0°F
Dead Band=3.0°F
StartDelta=5.0°F
StopDelta=2.0°F
Figure 7, Staging/Starting Temperatures
EWT
50.0°F
Evap Delta-T Set 10.0°F
46.5°F
Start Delta T
½ DB
LWT Set
40.0°F
½ DB
Stop Delta T
14
41.5°F
40.0°F
38.5°F
36.5°F
For a warm start-up (no
compressors running), the
first compressor will start
at any temperature above
46.5°F. Each subsequent
compressor will start after
the Stage Up Timer has
timed out and if the
temperature is above the
dead band, 41.5°F in this
case.
OM WGZC-1
If the LWT stays above 41.5°F, all of three (or 5) remaining compressors will
eventually stage on after the Stage Up Timer times out between each stage.
At some point, the chilled water temperature will be dropping and begin to approach
the point when compressors should begin staging off, which is the LWT setpoint minus
½ of the Dead Band, 38.5°F in this case. If the LWT remains below LWT setpoint
minus ½ Dead Band and the Stage Down Timer times out, additional compressors will
stage off. The last compressor will stage off when the LWT falls below the LWT
Setpoint minus ½ the Dead Band minus the Stop Delta T. The stop Delta T is in effect
for only the last compressor running.
If the temperature climbs above 38.5°F all running compressors will remain on. No
compressor staging occurs within the Dead Band. The next-on compressor will start
when the chilled water temperature reaches 41.5°F and the Stage Up Timer times out.
However, in some circumstances this methodology can cause the LWT to drop to
dangerously low levels, with the evaporating temperature below the freeze point,
before stopping. In the example shown in Figure 7, the Shutdown Temp (last
compressor off) would be 36°F.
This would result in a refrigerant evaporating temperature approaching freezing, so the
rule is amended to read:
If the Cool Leaving Water Temperature (LWT) set point is less than half
the Control Band above 39.0° F the Stage Down temperature is
calculated as:
Stage Down Temperature = Cool LWT – (Cool LWT - 39.0° F), and the
Shutdown Temperature = Cool LWT – (Cool LWT - 39.0° F) – Stop Delta T
This keeps the Stage Down Temp above 39°F and the Shutdown Temp above 36°F, as
the maximum Stop Delta T allowed is 3-degrees.
Which compressor starts and stops. One compressor per circuit will start before
starting the second compressor (or third) on any circuit. In other words, the
compressor with the lowest number of starts will start first. The compressor with the
lowest number of starts on the other circuit will start next, so that one compressor on
each circuit will be running. The third compressor on will be the compressor on either
circuit with the fewest starts. The remaining compressor will be the last on. If a circuit
is unavailable for any reason, the second compressor. on the operating circuit will stage
on. Only two (or three) compressors (on the one circuit) will be operating.
There is a 150 second delay after power-up before any compressor is allowed to start.
When staging down, one compressor on each circuit will be left on until each circuit
has only one compressor running. In other words, the compressor, on either circuit,
with the most run-hours will stop first. The compressor with the most run-hours on the
other circuit will stop next. One compressor on each circuit will be running. The third
compressor off will be the one, on either circuit, with the most run-hours. The
remaining compressor will be the last off. See the following description of pumpdown.
Table 3, Staging in Cool and Glycol Mode
Description
Stage #1 ON
(See Notes Below)
Stage #2 ON
Stage #3 ON
Stage #4 ON
Occurs When:
Lvg Evap T > Evap LWT SP + (DB/2) + Startup
Delta T
After Stage Up Delay times out then, LVG Evap
T > Evap LWT SP + (DB/2)
After Stage Up Delay times out, then LVG Evap
T > Evap LWT SP + (DB/2)
After Stage Up Delay times out then, LVG Evap
T > Evap LWT SP + (DB/2)
Action Taken
Available compressor with least
starts, ON
Available compressor on the other
circuit with least starts, ON
Available compressor on either circuit
with least starts, ON
Remaining compressor, ON
Continued next page.
OM WGZC-1
15
Description
Stage #4 OFF
Occurs When:
After Stage Down Delay times out then, LVG
Evap T < Evap LWT SP – (CB/2)
Stage #3 OFF
After Stage Down Delay times out then, LVG
Evap T < Evap LWT SP – (DB/2)
Stage #2 OFF
After Stage Down Delay times out then, LVG
Evap T < Evap LWT SP – (DB/2)
Stage #1 OFF
After Stage Down Delay times out then, LVG
Evap T < Evap LWT SP – (DB/2)-StopDelta T
Note 1: DB (Dead Band) = Evap Water Delta T x .3
Action Taken
Compressor with most run hours,
OFF
Compressor on the other circuit with
most run hours, OFF
Compressor on either circuit with
most run hours, OFF
Remaining compressor, OFF
Manual Compressor Disable Logic
Logic is available that allows the operator to manually enable and disable compressors.
When a compressor is disabled, it is considered unavailable to start in the staging logic.
This allows a damaged compressor to be taken offline while the remaining compressor
can still provide some cooling
•
•
•
•
The Compressor Disable set points are found on Compressor Set Points screens
three and four.
A running compressor cannot be disabled until it has been shutdown.
If all of the compressors on a circuit are disabled, then the circuit will be disabled.
If both circuits have all of their compressors disabled, then the Unit State will
remain Off
Automatic Pumpdown
WGZ units are equipped with single pumpdown control. When the last compressor
running on either circuit is ready to shut off, the liquid line solenoid valve (LLSV) is
closed first and the compressor continues to run until the pumpdown pressure is
reached, at which time the compressor shuts off. The shut off pressure is set at 15 psi
below the Low Evaporator pressure Unload setpoint.
When the first compressor on a circuit starts, the LLSV opens simultaneously.
Manual Pumpdown
When the Pumpdown Switch is in the pumpdown position, all compressors except #1
and #2 will shut off. Then the Liquid Line and Hot Gas Bypass Valves will close. The
operating compressor will pump out the refrigerant. When the Suction Pressure is at
40 psig, the compressors will stop.
Chilled Water and Condenser Water Pumps
The chiller MicroTech II controller can be programmed to start and stop the system
chilled water and condenser water pumps. They may also be controlled by the BAS or
manually. Programming directions and the sequence of operation can be found
beginning on page 41.
Cooling Tower Control
The cooling tower fans and/or the tower bypass valve can be controlled by the
MicroTech II controller. This provides a simple and direct method to control the unit’s
discharge pressure. Programming directions and the sequence of operation can be
found on page 70. Some means of discharge pressure control must be installed if the
condenser water temperature can fall below 60°F (16°C).
16
OM WGZC-1
Condenser Fan Control
Model AC chillers equipped with air-cooled or evaporative-cooled condensers usually
require some form of discharge pressure control. The MicroTech II controller can be
programmed to provide this function by cycling condenser fans based on the unit
discharge pressure. Directions on the pressure settings can be found on page 70.
ICE
In ICE mode, the compressors stage to 100% load until the LWT is less than the ICE
LWT SP. Then Compressors #3 and #4 shut down. Following that, Compressors #1
and #2 shut down after going through normal pumpdown on both circuits. There is a
programmable, start-to-start, Ice Mode Start Delay that limits the frequency of starts
when in the ice mode. The timer can be manually cleared to force a restart.
OM WGZC-1
17
MicroTech II Controller
Controller Software Version
This manual is based on software version WGZD20102E. The “02E” is the version
descriptor. The version installed in a unit can be viewed by pressing the MENU and
ENTER keys simultaneously, then pressing MENU to return to the regular menu
screen.
General Description
The MicroTech II controller’s state-of-the-art design will not only permit the chiller to
run more efficiently but will also simplify troubleshooting if a system failure occurs.
Every MicroTech II controller is programmed and tested prior to shipment to assist in a
trouble-free start-up. The MicroTech II controller can be used to cycle fans on remote
air-cooled condensers for head pressure control when the setpoint Water Cooled=N is
selected in one of the setpoint menu screens. Water Cooled=Y sets the chiller for
operation with the water-cooled condenser.
Operator Friendly
The MicroTech II controller menu structure is separated into three distinct categories,
which provide the operator or service technician with a full description of 1) current
unit status, 2) control parameters (setpoints), and 3) alarms. Security protection
prevents unauthorized changing of the setpoints and control parameters.
The MicroTech II controller continuously performs self-diagnostic checks, monitoring
all system temperatures, pressures and protection devices, and will automatically
shutdown a compressor, a refrigerant circuit or the entire unit should a fault occur. The
cause of the shutdown and date stamp are retained in memory and can be easily
displayed in plain English for operator review, which is an extremely useful feature for
troubleshooting. In addition to displaying alarm diagnostics, the MicroTech II chiller
controller also provides the operator with a warning of pre-alarm conditions.
Staging
The four scroll (or six) compressors are staged on and off as a function of leaving
chilled water temperature, number of starts and run-hours. See Sequence of Operation.
Equipment Protection
The unit is protected by alarms that shut it down and require manual reset, and also by
limit alarms that limit unit operation in response to some out-of-limit condition. Shut
down alarms activate an alarm signal that can be wired to a remote device.
Unit Enable Selection
Enables unit operation from local keypad or digital input.
Unit Mode Selection
Selects standard cooling, ice, glycol, or test operation mode.
18
OM WGZC-1
Keypad/Display
A 4-line by 20-character/line liquid crystal display and 6-key keypad is mounted on the
unit controller. Its layout is shown below.
Figure 8, Keypad and Display in MENU Mode
Key to Screen Pathway
Menu Key
Air Conditioning
< ALARM
<
VIEW
<
SET
Arrow Keys
"Enter" Key
The four arrow keys (UP, DOWN, LEFT, RIGHT) have three modes of use.
Scroll between data screens as indicated by the arrows (default mode).
Select a specific data screen in a hierarchical fashion using dynamic labels on the
right side of the display (this mode is entered by pressing the MENU key).
Change field values in edit mode according to the following table:
LEFT
Default
RIGHT Cancel
UP
Increment
DOWN Decrement
These four edit functions are indicated by one-character abbreviation on the right side
of the display (this mode is entered by pressing the ENTER key).
Inputs/Outputs
Table 4, Analog Inputs
C1 = Refrigerant Circuit #1, C2 = Refrigerant Circuit #2, UT = Unit, *n = Refrig. Dependent
#
Description
Type
Signal Source
Range
*1 Evaporator Refrigerant Pressure #1 (R134a,R22,R407c)
C1
0.1 to 0.9 VDC
0 to 132 psi
*1 Evaporator Refrigerant Pressure #1 (R410a)
C1
0.1 to 0.9 VDC
0 to 350 psi
*2 Evaporator Refrigerant Pressure #2 (R134a,R22,R407c)
C2
0.1 to 0.9 VDC
0 to 132 psi
*2 Evaporator Refrigerant Pressure #2 (R410a)
C2
0.1 to 0.9 VDC
0 to 350 psi
*3 Condenser Refrigerant Pressure #1 (R134a,R22,R407c)
C1
0.1 to 0.9 VDC
3.6 to 410 psi
*3 Condenser Refrigerant Pressure #1 (R410a)
C1
0.1 to 0.9 VDC
0 to 700 psi
-58 to 212°F
4
Leaving Evaporator Water Temperature
UT
NTC Thermister
(10k@25°C)
5
Condenser Entering Water Temperature or Outside
Ambient Temperature (See Note below)
UT
NTC Thermister
(10k@25°C)
-58 to 212°F
*6 Condenser Refrigerant Pressure #2 (R134a,R22,R407c)
C2
0.1 to 0.9 VDC
3.6 to 410 psi
*6 Condenser Refrigerant Pressure #2 (R410a)
C2
0.1 to 0.9 VDC
0 to 700 psi
7
Reset of Leaving Water Temperature
UT
4-20 mA Current
0-(10 to 80°F)
8
Demand Limit (R22,R-407CR410A)
UT
4-20 mA Current
0-100 % Load
Compressor Suction Temperature #1
C1
NTC Thermister
(10k@25°C)
-58 to 212°F
10 Compressor Suction Temperature #2
C2
NTC Thermister
(10k@25°C)
-58 to 212°F
9
Note:
1. If Water Cooled = Y, then Entering Condenser. If Water Cooled = N, then Outside Ambient.
2. Selection of R134a in unit setpoint screen will modify unit operation for Templifier
application.
OM WGZC-1
19
Table 5, Analog Outputs
#
Description
Output Signal
Range
0 to 100% Open
1
Cooling Tower Bypass Valve Position
0 to 10 VDC
2
Cooling Tower VFD Speed
0 to 10 VDC
0 to 100%
3
Circuit #1 Electronic Expansion Valve
0 to 10 VDC
0 to 100%
4
Circuit #2 Electronic Expansion Valve
0 to 10 VDC
0 to 100%
NOTE: Analog outputs 3 & 4 are for R410A and R134a units only.
Table 6, Digital Inputs
The following parameters are digital inputs to this controller.
C1 = Refrigerant Circuit #1, C2 = Refrigerant Circuit #2, UT = Unit, *n = Refrigerant Dependent
#
Description
Type
Signal
Signal
UT
0 VAC (Stop)
24 VAC (Auto)
C1
0 VAC (Stop)
24 VAC (Start)
UT
0 VAC (No Flow)
24 VAC (Flow)
0 VAC (Fault)
24 VAC (No Fault)
1
Unit OFF Switch
2
Pump Down Switch #1
3
Evaporator Water Flow Switch
*4
Motor Protection #1 (R22, R407c)
C1
*4
Open (R134a,R410a)
5
Open
6
Pump Down Switch #2
C2
0 VAC (Stop)
24 VAC (Start)
*7
Motor Protection #2 (R22,R407c)
C2
0 VAC (Fault)
24 VAC (No Fault)
*7
Open (R134a,R410a)
*8
Open (R22,R407c)
*8
Condenser Water Flow Switch (R134a,R410a)
UT
0 VAC (No Flow)
24 VAC (Flow)
9
Phase Voltage Fault #1 (See Note 1 Below)
C1
0 VAC (Fault)
24 VAC (No Fault)
10
Phase Voltage Fault #2 (See Note 1 Below)
C2
0 VAC (Fault)
24 VAC (No Fault)
11
Ground Fault Prot. #1 (See Note 2 Below)
C1
0 VAC (Fault)
24 VAC (No Fault)
12
Ground Fault Prot. #2 (See Note 2 Below)
C2
0 VAC (Fault)
24 VAC (No Fault)
13
Remote Start/Stop
UT
0 VAC (Stop)
24 VAC (Start)
*14
Condenser Water Flow Switch(R22,R407c)
UT
0 VAC (No Flow)
24 VAC (Flow)
*14
Open (R134a,R410a)
*15
Open (R22,R407c)
*15
Motor Protection #1 (R134a,R410a)
C1
0 VAC (Fault)
24 VAC (No Fault)
*16
Open (R22,R407c)
*16
Motor Protection #2 (R134a,R410a)
C2
0 VAC (Fault)
24 VAC (No Fault)
17
Ice Mode Switch
UT
0 VAC (Normal)
24 VAC (Ice)
18
Heat Mode Switch
UT
0 VAC (Normal)
24 VAC (Heat)
Note 1: See Safety Alarms Table for “Phase Voltage Protection”. Units with single point electrical connection will
have one PVM with Inputs 9 and 10 wired together. Units with multiple point connection will have two PVM’s
with Input 9 for Electrical Circuit #1 and Input 10 for Electrical Circuit #2.
Note 2: See Safety Alarms Table for “Ground Fault Protection”. Units with single point electrical connection will
have one GFP with Inputs 11 and 12 wired together. Units with multiple point connection will have two GFP’s
with Input 11 for Electrical Circuit #1 and Input 12 for Electrical Circuit #2.
Table 7, Digital Outputs
The following parameters are digital outputs from this controller.
C1 = Refrigerant Circuit #1, C2 = Refrigerant Circuit #2, UT = Unit, *n = Refrigerant
Dependent
#
20
Description
1
Alarm
2
Evaporator Water Pump
3
Condenser Fan #1 – Water Cooled = N /
Condenser Water Pump – Water Cooled = Y
4
Motor Control Relay #1 = Compr#1
Type
Load
Output OFF
C1,C2,UT
Alarm Indicator
Alarm OFF
Output ON
Alarm ON
UT
Pump Contactor
Pump OFF
Pump ON
C1 / UT
Fan Contactor/
Pump Contactor
Fan OFF
Fan ON
C1
Starter
Compressor OFF Compressor ON
OM WGZC-1
Continued next page.
Table 7, Continued
#
Type
Load
Output OFF
Output ON
5
Motor Control Relay #3 = Compr#3
Description
C1
Starter
Compressor OFF
Compressor ON
*6
Condenser Fan #3– Water Cooled =N /Tower Fan
#2-Water Cooled=Y
(R22,R407C)
C1 /
UT
Fan Contactor
Fan OFF
Fan ON
*6
Motor Control Relay #5 = Compr#5 (R134a,R410a)
C1
Starter
Compressor OFF
Compressor ON
7
Liquid Line #1
C1
Solenoid
Cooling OFF
Cooling ON
8
Condenser Fan #2 – Water Cooled =N /Tower Fan
#1-Water Cooled=Y
C2 /
UT
Fan Contactor
Fan OFF
Fan ON
9
Motor Control Relay #2 = Compr#2
C2
Starter
Compressor OFF
Compressor ON
10 Motor Control Relay #4 = Compr#4
C2
Starter
Compressor OFF
Compressor ON
*11 Condenser Fan #4 (R22,R407c)
C2
Fan Contactor
Fan OFF
Fan ON
*11 Motor Control Relay #6 = Compr#6 (R134a,R410a)
C2
Starter
Compressor OFF
Compressor ON
12 Liquid Line #2
Cooling OFF
Cooling ON
C2
Solenoid
13 Condenser Fan #5
C1
Fan Contactor
Fan OFF
Fan ON
14 Hot Gas Bypass #1
C1
Solenoid
Cooling OFF
Cooling ON
15 Hot Gas Bypass #2
C2
Solenoid
Cooling OFF
Cooling ON
*16 Condenser Fan #6 (R22,R407c)
C2
Fan Contactor
Fan OFF
Fan ON
*16 Condenser Fan #4 (R134a,(R410a)
C2
Fan Contactor
Fan OFF
Fan ON
*17 Condenser Fan #7 (R22,R407c)
C1
Fan Contactor
Fan OFF
Fan ON
*17 Condenser Fan #5&7 (R134a,R410a)
C1
Fan Contactor
Fan OFF
Fan ON
18 Condenser Fan #8
C2
Fan Contactor
Fan OFF
Fan ON
18 Condenser Fan #6&8
C2
Fan Contactor
Fan OFF
Fan ON
Expansion I/O Controller
Digital Outputs
The following parameters are digital outputs from this controller.
Types: C1 = Refrigerant Circuit #1, C2 = Refrigerant Circuit #2, UT = Unit
#
Description
Type
Output Off
1
Evap Water Pump Output #2
UT
Pump Off
Output On
Pump On
2
Cond Water Pump Output #2
UT
Pump Off
Pump On
3
Condenser Fan #9
C1
Fan OFF
Fan ON
4
Condenser Fan #10
C2
Fan OFF
Fan ON
Analog Inputs
The following parameters are digital outputs from this controller for Templifier operation
only.
Types: C1 = Refrigerant Circuit #1, C2 = Refrigerant Circuit #2, & UT = Unit
OM WGZC-1
#
Description
Type
Output Off
Output On
1
Entering Evaporator Water Temperature
(R134a)
UT
NTC Thermister
(10k@25°C)
-58 to 212°F
2
Demand Limit (R134a)
UT
4-20 mA Current
0-100 % Load
-58 to 212°F
-58 to 212°F
3
Liquid Line Temperature #1 (R134a)
C1
NTC Thermister
(10k@25°C)
4
Liquid Line Temperature #2 (R134a)
C2
NTC Thermister
(10k@25°C)
21
Setpoints
The following parameters are remembered during power off, are factory set to the Default
value, and can be adjusted to any value in the Range column.
The PW (password) column indicates the password level that must be active in order to
change the setpoint. Passwords are as follows:
O = Operator [0100]
M = Manager [2001]
Table 8, Setpoints
Description
Unit Enable
*Unit Mode (R22, R407C, R410A
&Unit Mode (R134a)
Control source
Default
Range
PW
Off
Cool
Off, On
Cool, Cool w/Glycol, Ice w/Glycol, Test
O
O
Cool
Cool, Cool w/Glycol, Heat, Test
Switches
20.0°F
Keypad, Network, Switches
Cool, Cool w/Glycol, Cool/Ice w/Glycol
Ice w/Glycol, Test
Test, Cool, Cool w/Glycol, Cool/Heat, COOL/HEAT
w/Glycol, Heat w/Glycol,
Without Glycol: 40.0 to 60.0°F
40.0 to 85.0°F (R134a Only)
With Glycol: 20.0 to 60.0°F (R22,R407C)
10.0 to 60.0°F (R410A)
20.0 to 85.0°F (R134a)
20.0 to 40.0 °F
110 to 165°F
6.0 to 16.0 °F
1.0 to 15.0 °F
0 to 3.0 °F
0.5 to 5.0 °F
15 to 300 seconds
#1 Only, #2 Only, Auto, #1 Prim,
#2 Prim
5.0 to 40.0°F
30
15 to 90 seconds
M
#1 Only
#1 Only, #2 Only, Auto, #1 Prim, #2 Prim
M
*Available Modes (R22,R407C,R410A)
Cool
*Available Modes (R134a)
Cool
Evap LWT
44. 0 °F
Ice LWT
Heat LWT (R134a only)
Evap Delta T
Startup Delta T
Stop Delta T
Max Pulldown Rate
Evap Recirculate Timer
Evap Pump
(Refrigerant = R410a,R134a)
Cond Delta T (R134a only)
Cond Pump Recirculate Timer
(Water-cooled = Yes)
Cond Pump
(Water-cooled=Yes & Ref=R410A or R134a
40. 0 °F
110.o°F
10.0 °F
10.0 °F
0.5 °F
1.0 °F
30
#1 Only
Low Ambient Lockout(Water-Cooled = No)
35.0 °F
Demand Limit
* Water Cooled
Ice Time Delay
Clear Ice Delay
Hot Gas Delay Time
BAS Protocol
Ident number
Baud rate
Units
Language
* Refrigerant Select
Compressor
# of Compressors
(Refrig = R410A or R134a to select 6)
Clear Cycle Tmr
Stage Up Delay
Stage Down Delay
Start-Start
Stop-Start
Off
Off
12 hrs
No
30 sec.
Modbus
001
9600
F/psi
English
None
35 to 70 °F
If Speedtrol = Yes
-2.0 to70.0°F (R22,R407C)
-10.0 to 70.0 (R410A)
N/A (R134a)
Off, On
Off, On
1 to 23 hrs
No, Yes
30 to 180 seconds
BACnet, LonWorks, Modbus
000-200
1200,2400,4800,9600,19200
F/psi (only)
English (only)
R22, R407C, R410A, R134a
O
M
M
O
O
O
O
O
O
M
M
M
M
M
M
M
M
M
M
M
M
4
4, 6
M
Off
240 sec
30
15 min
5 min
On/Off
90 to 480 seconds
20 to 60 sec
10 to 60 min
3 to 20 min
M
M
M
M
M
Continued next page.
22
OM WGZC-1
Table 8, Continued
Description
Expansion Valve Type
Circuit 1 EXV Control
Circuit 1 EXV Position
Circuit 2 EXV Control
Circuit 2 EXV Position
Alarms
Low Evap Pressure-Hold
Low Evap Pressure-Unload
High Cond Pressure – Unload
High Cond Pressure – Stop
Default
Range
PW
Electronic
Auto
N/A
Auto
N/A
Thermal, Electronic
Auto, Manual
0-100%
Auto, Manual
0-100%
M
M
M
M
M
See Dynamic
Defaults
(following)
See following section; Automatic Adjusted
Limits
M
M
M
M
Evap. Freeze
38.0 °F
Cond. Freeze
High Condenser Pressure Stop
(Water-Cooled = Y
High Condenser Pressure Stop
(Water Cooled = N)
High Condenser Pressure Stop (R134a)
Evap Flow Proof
Cond Flow Proof
Recirc Timeout
* Phase Voltage Protection
* Ground Fault Protection
Low OAT Start Time
Condenser Fans (Water Cooled = N)
Number of fans
Speedtrol Option
Stg on Deadband Stg 2
Stg on Deadband Stg 3
Stg on Deadband Stg 4
Stg Off Deadband Stg 1
Stg Off Deadband Stg 2
Stg Off Deadband Stg 3
Stg Off Deadband Stg 4
Cond Sat Temp Target
Forced Fan 1 (>75°F)
Forced Fan 2 (>90°F)
Forced Fan 3 (>105°F)
Cooling Tower (Water Cooled = Y)
Tower Control
Tower Stages
Stage Up Time
Stage Down Time
Stage Differential
Stage #1 On
Stage #2 On
34.0 °F
280 psi
420 psi
380 psi
565 psi
185 psi
5 sec.
5 sec.
3 min.
N
N
60 sec.
37.0 to 42.0 °F
Glycol: 17.5 to 42.0°F (R134a,R22, R407C)
7.5 to 42.0°F (R410A)
18 to 42 °F
260 to 380 psi (R22, R407C)
375 TO 425 psi (R410A)
260 to 380 psi (R22, R407C)
425 to 570 psi (R410A)
170 to 425 psi
5 to 15 seconds
5 to 15 seconds
1 to 10 minutes
N,Y
N,Y
30 to 240 seconds
4
No
15 °F
10°F
10°F
20°F
15°F
10°F
10°F
100°F
4 to 8 (10 for R410a)
No,Yes
15 to 25°F
10 to 15°F
10 to 15°F
15 to 20°F
10 to 15°F
6 to 10°F
6 to 10°F
80 to 120°F
M
M
M
M
M
M
M
M
M
M
None
2
2 min
5 min
3.0 °F
70 °F
75 °F
None, Temperature
0 to 2
1 to 60 min
1 to 60 min
1.0 to 10.0 °F
40 to 120 °F
40 to 120 °F
None, Valve Set point, Valve Stage, VFD
Stage, Valve SP/VFD Stage
60 to 120 °F
1.0 to 10.0 °F
0 to 100%
0 to 100%
0 to 100%
0 to 100%
NC, NO
0 to 100%
0 to 100 °F
0 to 100%
0 to 100 °F
10 to 99
10 to 99
M
M
M
M
M
M
M
Valve/VFD Control
Valve Setpoint
Valve Deadband
Stage Fan Down @
Stage Fan Up @
Valve Control Range (Min)
Valve Control Range(Max)
Valve Type
Minimum Start Position
Minimum Position @
Maximum Start Position
Maximum Position @
Error Gain
Slope Gain
None
65 °F
2.0 °F
20%
80%
10%
90%
NC to tower
0%
60 °F
100%
90 °F
25
25
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
* Set at McQuay .factory.
OM WGZC-1
23
Automatic Adjusted Limits
The following are set points that will be limited based on the option selected.
Evaporator Leaving Water Temperature
Mode
Refrigerant Type
Range
R134a,R22, R407C, R410A
40 to 60°F
Unit Mode = Cool w/Glycol
R134a,R22, R407C
20 to 60°F
Unit Mode = Cool w/Glycol
R410a
15 to 60°F
R22, R407C,R410A
20 to 40°F
Unit Mode = Cool
Unit Mode = Ice
Condenser Leaving Water Temperature
Mode
Refrigerant Type
Range
R134a
110 to 160ºF
Refrigerant Type
Range
R134a,R22, R407C, R410A
36 to 42°F
R134a,R22, R407c
18 to 42°F
R410A
12.5 to 42°F
Unit Mode= HEAT
Evaporator Freeze Temperature
Mode
Unit Mode = Cool
Unit Mode = Cool w/Glycol, Ice
w/Glycol
Unit Mode = Cool w/Glycol, Ice
w/Glycol
Ice Leaving Water Temperature
Refrigerant Type
Range
R134a
N/A
R22, R407C
20 to 40°F
R410A
15 to 40°F
Low Evaporator Pressure Inhibit Loading and Unloading
Mode
Refrigerant Type
Range
Unit Mode = Cool
R134a
R22
R407C
R410A
26 to 54 psi
55 to 65 psi
58 to 75 psi
97 to 115 psi
Unit Mode = Cool w/Glycol, Ice
w/Glycol
R134a
R22
R407C
R410A
12 to 54 psi
24 to 65 psi
20 to 75 psi
48 to 115 psi
Low Ambient Lockout Temperature
Speedtrol
24
Range
Speedtrol = N
35 – 70°F
Speedtrol = Y
-2 – 70°F
OM WGZC-1
Dynamic Defaults
Some set points will have a particular default value loaded when another setting is
changed.
Refrigerant Dependent Defaults
Set Point
Refrigerant Type
R134a
R22
R407C
R410A
Low Evaporator Pressure Hold
29 psi
59 psi
60 psi
101 psi
Low Evaporator Pressure Unload
28 psi
58 psi
59 psi
100 psi
High Condenser Pressure Unload
170 psi
370 psi AC
265 psi WC
370 psi AC
265 psi WC
550 psi AC
405 psi WC
High Condenser Pressure
185 psi
380 psi AC
280 psi WC
380 psi AC
280 psi WC
565 psi AC
420 psi WC
AC = Air Cooled, WC = Water Cooled (R134a is water cooled ONLY)
Number of Fans Dependent Defaults
When the number of fans setting is changed, the forced fan set points will default to
values as shown in the following table:
Set Point
Number of Fans Set Point
4
6
8
10
Forced Fan 1 (>75°F)
1
1
1
1
Forced Fan 2 (>90°F)
1
1
2
2
Forced Fan 3 (>105°F)
2
2
3
3
Events & Alarms
Situations may arise that require some action from the chiller or that should be logged
for future reference. Conditions that cause a shutdown and require manual reset is
known as a stop alarm. Other conditions can trigger what is known as an event, which
may or may not require action in response. All stop alarms and events are logged.
Unit Stop Alarms
The alarm output and red button is turned ON when any stop alarm occurs and turned
off when all alarms have been cleared.
Evaporator Flow Loss
Alarm description (as shown on screen): Evaporator Flow Loss
Trigger:
1: Evaporator Pump State = Run AND Evaporator Flow Digital Input = No Flow for
time > Evap Flow Proof Set Point AND at least one compressor running.
2: Evaporator Pump State = Start for time greater than Recirc Timeout Set Point AND
all pumps have been tried AND Evaporator Flow Digital Input = No Flow.
Action Taken: Rapid stop all circuits.
OM WGZC-1
25
Reset:
This alarm can be cleared at any time manually via the keypad or via the BAS clear
alarm signal.
If active via trigger condition 1:
When the alarm occurs due to this trigger, it can auto reset the first two times each day,
with the third occurrence being manual reset.
For the auto-reset occurrences, the alarm will reset automatically when the evaporator
state is Run again. This means the alarm stays active while the unit waits for flow, then
it goes through the recirculation process after flow is detected. Once the recirculation is
complete, the evaporator goes to the Run state which will clear the alarm. After three
occurrences, the count of occurrences is reset and the cycle starts over if the manual
reset flow loss alarm is cleared.
If active via trigger condition 2:
If the flow loss alarm has occurred due to this trigger, it is always a manual reset alarm.
Condenser Flow Loss (Note: WaterCooled = On & TGZ units Only)
Alarm description (as shown on screen): Condenser Flow Loss
Trigger:
1: Condenser Pump State = Run AND Condenser Flow Digital Input = No Flow for
time > Cond Flow Proof Set Point AND at least one compressor running.
2: Condenser Pump State = Start for time greater than Recirc Timeout Set Point AND
all pumps have been tried AND Condenser Flow Digital Input = No Flow.
Action Taken: Rapid stop all circuits.
Reset:
This alarm can be cleared at anytime manually via the keypad or via the BAS clear
alarm signal.
If active via trigger condition 1:
When the alarm occurs due to this trigger, it can auto reset the first two times each day,
with the third occurrence being manual reset.
For the auto-reset occurrences, the alarm will reset automatically when the condenser
pump state is Run again. This means the alarm stays active while the unit waits for
flow, then it goes through the recirculation process after flow is detected. Once the
recirculation is complete, the condenser pump goes to the Run state which will clear
the alarm. After three occurrences, the count of occurrences is reset and the cycle starts
over if the manual reset flow loss alarm is cleared.
If active via trigger condition 2:
If the flow loss alarm has occurred due to this trigger, it is always a manual reset alarm.
Low Evaporator Pressure
Alarm description (as shown on screen): Evap Press Low Cir N
Trigger: [Circuit State = Run AND Freezestat trip AND Low OAT Start not active]
OR Evaporator Press < Absolute Low Pressure Limit AND Circuit State = Run
26
OM WGZC-1
The absolute low pressure limit is 5 psi with R134a, R22, and R407C refrigerants and
20 psi with R410A refrigerant.
Freezestat logic allows the circuit to run for varying times at low pressures. The lower
the pressure, the shorter the time the compressor can run. This time is calculated as
follows:
Freeze error = Low Evaporator Pressure Unload – Evaporator Pressure
Freeze time =
[60 – 2.7 x freeze error] with R134a refrigerant, limited to a range of 20-60
seconds
[60 – 1.6 x freeze error] with R22 and R407C refrigerant, limited to a range of
20-60 seconds
[60 – freeze error] with R410A refrigerant, limited to a range of 20-60 seconds
When the evaporator pressure goes below the Low Evaporator Pressure Unload set
point, a timer starts. If this timer exceeds the freeze time, then a ‘Evap Press Low Cir
N’ alarm trip occurs. If the evaporator pressure rises to the unload set point or higher,
and the freeze time has not been exceeded, the timer will reset.
Action Taken: Rapid stop circuit
Reset: This alarm can be cleared manually via the keypad if the evaporator pressure is
above the absolute low-pressure limit.
High Condenser Pressure
Alarm description (as shown on screen): Cond Press High Cir N
Trigger: Condenser Pressure > High Condenser Pressure Set Point
Action Taken: Rapid stop circuit
Reset: This alarm can be cleared manually via the keypad.
Mechanical High Pressure/Motor Protect
Alarm description (as shown on screen): MHP or Motor Prot N
Trigger: MHP/MP input is low and over 150 seconds lapsed since controller boot-up
Action Taken: Rapid stop circuit
Reset: This alarm can be cleared manually via the keypad if the MHP/MP input is
high.
Phase Voltage Protection
Alarm description (as shown on screen): Phase/Voltage Cir N
Trigger: PVM input is low and Phase Voltage set point = enable.
Action Taken: Rapid stop circuit
Reset: Auto reset when PVM input is high
Ground Fault Protection
Alarm description (as shown on screen): Ground Fault Cir N
Trigger: GFP input is low and Ground Fault set point = enable.
Action Taken: Rapid stop circuit
Reset: This alarm can be cleared manually via the keypad.
Low OAT Restart Fault
Alarm description (as shown on screen): Low OAT Start Fail N
Trigger: Circuit has failed three low OAT start attempts
Action Taken: Rapid stop circuit
Reset: This alarm can be cleared manually via the keypad.
OM WGZC-1
27
Evaporator Water Freeze Protect
Alarm description (as shown on screen): Evap Water Freeze
Trigger: Evaporator LWT drops below evaporator freeze protect set point AND Unit
State = Auto
Action Taken: Rapid stop all circuits
Reset: This alarm can be cleared manually via the keypad or via the BAS clear alarm
signal, but only if the alarm trigger conditions no longer exist.
Leaving Evaporator Water Temperature Sensor Fault
Alarm description (as shown on screen): Evap LWT Sens Fault
Trigger: Sensor shorted or open
Action Taken: Normal stop all circuits
Reset: This alarm can be cleared manually via the keypad, but only if the sensor is
back in range.
Leaving Condenser Water Temperature Sensor Fault
Alarm description (as shown on screen): CondLWT Sens Fault
Trigger: Sensor shorted or open AND TGZ unit (refrig = R134a) AND operating in
‘heat’ mode.
Action Taken: Normal stop all circuits
Reset: This alarm can be cleared manually via the keypad, but only if the sensor is
back in range.
Suction Temperature Sensor Fault
Alarm description (as shown on screen): SuctT Sensor Fail N
Trigger: Sensor shorted or open AND Expansion Valve Type = Electronic
Action Taken: Rapid stop circuit
Reset: This alarm can be cleared manually via the keypad, but only if the sensor is
back in range.
Evaporator Pressure Sensor Fault
Alarm description (as shown on screen): EvapP Sensor Fail N
Trigger: Sensor shorted or open. If failing high (open), logic has been added that
requires the Leaving Evaporator Temperature to be below 75°F. This will prevent
nuisance trips due to conditions where the evaporator water temperature is high which
could cause false alarms.
Action Taken: Rapid stop circuit
Reset: This alarm can be cleared manually via the keypad, but only if the sensor is
back in range.
Condenser Pressure Sensor Fault
Alarm description (as shown on screen): CondP Sensor Fail N
Trigger: Sensor shorted or open
Action Taken: Rapid stop circuit
Reset: This alarm can be cleared manually via the keypad, but only if the sensor is
back in range.
28
OM WGZC-1
Condenser Entering or Outdoor Air Temperature Sensor Fault
Alarm description (as shown on screen): OAT Sensor Fault
Trigger: Sensor shorted or open
Action Taken: Normal stop all circuits
Reset: This alarm can be cleared manually via the keypad, but only if the sensor is
back in range
Evaporator Water Freeze Protect
Alarm description (as shown on screen): Evap Water Freeze
Trigger: Evaporator LWT drops below evaporator freeze protect set point AND Unit
State = Auto
Action Taken: Rapid stop all circuits
Reset: This alarm can be cleared manually via the keypad or via the BAS clear alarm
signal, but only if the alarm trigger conditions no longer exist.
No Evaporator Pressure Drop
Alarm description (as shown on screen): No Evap Press Drop N
Trigger: After start of first compressor on the circuit, either a 1 psi drop in evaporator
pressure OR a 5 psi rise in condenser pressure has not occurred after 15 seconds
Action Taken: Rapid stop circuit
Reset: This alarm can be cleared manually via the keypad.
EXB Comm Failure on CP1
Alarm description (as shown on screen): No EXB comm CP1
Trigger: CP1 does not have communication with either EXB1 for 60 seconds after
power up. This alarm will only occur if 10 Fan , evaporator pump #2, or condenser
pump #2 operation is selected. After communication is established, when
communication is lost to either EXB an immediate shutdown occurs.
Action Taken: Rapid stop all circuits
Reset: Auto clear when EXB1 is communicating with CP1.
Alarm Log
An alarm log stores the last 25 alarms and/or events to occur. When an alarm or event
occurs, it is put into the first slot in the alarm log and all others are moved down one,
dropping the last entry. In the alarm log, the date and time the alarm occurred are
stored, as well as a list of other parameters. These parameters include compressor
states, evaporator pressure, condenser pressure, number of fans on, OAT, and
evaporator LWT.
Active Alarms
When an alarm occurs, it appears in the active alarm list. The active alarm list holds a
record of all active alarms, which includes the date and time each occurred.
Clearing Alarms
A password is NOT required to clear an active alarm. Active alarms must be cleared at
the unit controller. To clear active alarms scroll down to the end of the Active Alarm
list press Enter to clear all active alarms. If the user attempts to clear an alarm while the
alarm condition still exists, a new alarm will be generated immediately.
OM WGZC-1
29
Limit Events
The following events do not cause a rapid stop but limit operation of the chiller in
some way as described in the Action Taken. All limit events do NOT appear in the
Active Alarm window and are NOT logged in the Alarm Log
Low Evaporator Pressure - Hold
Event description (as shown on screen): Evap Press Low HoldN
Trigger:
This event is triggered if all of the following are true:
• circuit state = Run
• circuit is not currently in a low OAT start
• has been at least 30 seconds since a compressor has started on the circuit.
• evaporator pressure <= Low Evaporator Pressure - Hold set point
Action Taken: Inhibit staging on of additional compressors on the circuit.
Reset: While still running, the event will be reset if evaporator pressure > (Low
Evaporator Pressure - Hold set point + 8psi for R134a/R22/R407C or 13 psi for
R410A). The event is also reset if the circuit state is no longer run.
Low Evaporator Pressure - Unload
Event description (as shown on screen): EvapPressLow Unload N
Trigger:
This event is triggered if all of the following are true:
• circuit state = Run
• more than one compressor is running on the circuit
• circuit is not currently in a low OAT start
• has been at least 30 seconds since a compressor has started on the circuit.
• evaporator pressure <= Low Evaporator Pressure - Unload set point for a time
greater than half of the current freezestat time
Action Taken: Stage off one compressor on the circuit every 10 seconds, except the
last one.
Reset: While still running, the event will be reset if evaporator pressure > (Low
Evaporator Pressure - Hold set point + 8psi for R134a/R22/R407C or 13 psi for
R410A). The event is also reset if the circuit state is no longer run.
High Condenser Pressure - Unload
Event description (as shown on screen): CondPressHighUnloadN
Trigger:
This event is triggered if all of the following are true:
• circuit state = Run
• more than one compressor is running on the circuit
• condenser pressure > High Condenser Pressure – Unload set point
Action Taken: Stage off one compressor on the circuit every 10 seconds, except the
last one.
Reset: While still running, the event will be reset if condenser pressure drops below
the “Hold Clear @” value which is displayed on that circuit’s VIEW CIRCUIT n (1)
screen. The “Hold Clear @” is calculated based on number of compressors, refrigerant,
and number of High Condenser Pressure – Unload occurrences since the circuit has
cycled off or since midnight. See table below:
30
OM WGZC-1
Condenser
Configuration
Compressor
s
R410A
R22
R407C
R134a
Step
Increase
4
40 psi
30 psi
30 psi
10 psi
6
30 psi
N/A
20 psi
10 psi
4
100 psi
70 psi
N/A
15 psi
6
80 psi
N/A
N/A
15psi
Water-Cooled
Air-Cooled
Failed Pumpdown
Event description (as shown on screen): Pumpdown Fail Cir N
Trigger: Circuit state = pumpdown for time > 60 seconds
Action Taken: Shutdown circuit
Reset: N/A
Condenser Freeze Event
Event description (as shown on screen): Cond Freeze Circ N
Trigger: Cond Sat Refr Temperatre < Condenser Freeze Set Point AND Condenser
Pump State = OFF
Action Taken: Start condense pump.
Reset: N/A
Condenser Freeze Event (Water Cooled = Y Only)
Event description (as shown on screen): Cond Freeze Circ N
Trigger: Cond Sat Refr Temp < Condenser Freeze Set Point AND Condenser Pump
State = OFF
Action Taken: Start condenser pump.
Reset: Cond Sat Refr Temp > Condenser Freeze Set Point plus 2°F.
Suction Temperature Sensor Fail
Event description (as shown on screen): SuctT Sensor Fail N
Trigger: Sensor shorted or open.
Action Taken: None.
Reset: N/A
Entering Evaporator Water Temperature Sensor Fail (TGZ unit only)
Event description (as shown on screen): Evap EWT Sensor Fail
Trigger: Sensor shorted or open.
Action Taken: None.
Reset: N/A
Liquid Line Temperature Sensor Fail (TGZ unit only)
Event description (as shown on screen): Low Source Temp
Trigger: Sensor shorted or open.
Action Taken: None.
Reset: N/A
OM WGZC-1
31
Low Source Water Temperature (TGZ unit in ‘heat’ mode only)
Event description (as shown on screen): LiqL Sensor Fail N
Trigger: Unit is in heat mode and the leaving evaporator water temperature drops
below the Low Source Temperature set point.
Action Taken: Stage off one compressor immediately and the remaining being staged
off based upon the “InterStage Dn” set point time interval.
Reset: N/A
EXB Comm Failure on CP1 (TGZ unit only)
Event description (as shown on screen): No EXB comm CP1
Trigger: CP1 does not have communication with either EXB1 for 60 seconds after
power up. This event is only active when the expansion board is not intended to
operate evaporator or condenser pump #2.
Action Taken: None.
Reset: N/A.
Event Log
An Event Log similar to the Alarm Log stores the last 25 Event occurrences. There
must be an active password for access to the Event Log. To navigate to the Event log
press the Left Arrow key from any Alarm Log screen. When an event occurs, it is
recorded in the first slot in the Event Log. All other entries are moved down in the
Event Log and the last entry is dropped if 25 earlier event occurrences have been
logged. Each Event Log entry includes an event description and a time and date stamp
for the event occurrence.
32
OM WGZC-1
Controller Operation
Calculations
The Control Band defines the temperatures around the Controlling Leaving Water
Temperature set point where compressors will be staged on or off. In cool mode, the
controlling leaving water temperature set point will be Evap LWT. In heat mode, the
controlling leaving water temperature set point will be Heat LWT.
In cooling mode, the Control Band is calculated as follows:
Control Band = Evap Delta Temperature Set Point * 0.3
units
Control Band = Evap Delta Temperature Set Point * 0.2
Four compressor
Six compressor units
In heating mode, the Control Band is calculated as follows:
Control Band = Cond Delta Temperature Set Point * 0.3
units
Four compressor
(Control Band/2)
Control
Band
Leaving Water Set Point
(Control Band/2)
Control Band = Cond Delta Temperature Set Point * 0.2
Six compressor units
If the Unit mode is Cool:
When the Cool Leaving Water Temperature set point is more than half the
Control Band above 39.0° F the Stage Up temperature is calculated as follows:
Stage Up Temperature = Cool LWT + (Control Band/2)
The Stage Down temperature is calculated as:
Stage Down Temperature = Cool LWT – (Control Band/2)
If the Cool Leaving Water Temperature set point is less than half the Control Band
above 39.0° F the Stage Down temperature is calculated as:
Stage Down Temperature = Cool LWT – (Cool LWT - 39.0° F)
Stage Up temperature is calculated as:
Stage Up temperature = Cool LWT + Control Band – (Cool LWT – 39.0°F)
In all other Unit modes the compressor staging temperatures are calculated as shown
below:
Stage Up Temperature = Cool LWT + (Control Band/2)
Stage Down Temperature = Cool LWT – (Control Band/2)
The Cool Start up and Shutdown temperatures are calculated from the Control Band.
The Start Up temperature determines when the first compressor on the unit will start.
The Start Up temperature calculation is shown below:
Start Up Temperature = Stage Up Temperature + Start Up Delta Temperature
OM WGZC-1
33
The Shutdown temperature defines when the last running compressor will shutdown.
The Shutdown temperature calculation is:
Shutdown Temperature = Stage Down Temperature – Shutdown Delta Temperature
If the Unit mode is Heat:
Stage Up temperature is calculated as follows:
Stage Up Temperature = Heat LWT - (Control Band/2)
The Stage Down temperature is calculated as:
Stage Down Temperature = Heat LWT + (Control Band/2)
The Heat Start up and Shutdown temperatures are calculated from the Control Band.
The Start Up temperature determines when the first compressor on the unit will start.
The Start Up temperature calculation is shown below:
Start Up Temperature = Stage Up Temperature - Start Up Delta Temperature
The Shutdown temperature defines when the last running compressor will shutdown.
The Shutdown temperature calculation is:
Shutdown Temperature = Stage Down Temperature + Shutdown Delta Temperature
Leaving Water Temperature (LWT) Reset
The active leaving water set point is set to the current Leaving Water Temperature
(LWT) set point unless the unit is in either cool or heat mode and any of the reset
methods below are selected. The type of reset in effect is determined by the LWT Reset
Type set point.
Reset Type = NONE
The Active Leaving Water Temperature set point is set equal to the current LWT set
point. IN cool mode, this will be Evap LWT and in heat mode this will be Heat LWT.
Reset Type = 4-20 mA
The Active Leaving Water set point is adjusted by the 4 to 20 mA reset analog input.
Cooling Mode
The Active Leaving Water set point is adjusted by the 4 to 20 mA reset analog input.
Parameters used:
1. Evaporator Leaving Water Temperature set point (Evap LWT)
2. Cooling Maximum Reset set point (Clg MaxRes)
3. LWT Reset signal 4-20mA
Reset is 0ºF and the active leaving water set point is equal to the Evap LWT set point if
the reset signal is less than or equal to 4 mA. Reset is equal to the Max Reset set point
and the active leaving water set point is equal to the Evap LWT plus Max Reset set
points if the reset signal equals or exceeds 20 mA. The amount of reset will vary
linearly between these extremes if the reset signal is between 4 mA and 20 mA. An
example of the operation of 4-20 reset in Cool mode is shown below.
34
OM WGZC-1
Heating Mode (only for TGZ unit Refrig = R134a)
The Active Leaving Water set point is adjusted by the 4 to 20 mA reset analog input.
Parameters used:
1. Heating Leaving Water Temperature set point (Heat LWT)
2. Heating Maximum Reset set point (Htg MaxRes)
3. LWT Reset signal 4-20mA
Reset is 0ºF and the active leaving water set point is equal to the Heat LWT set point if
the reset signal is less than or equal to 4 mA. Reset is equal to the Max Reset set point
and the active leaving water set point is equal to the Heat LWT minus Max Reset set
points if the reset signal equals or exceeds 20 mA. The amount of reset will vary
linearly between these extremes if the reset signal is between 4 mA and 20 mA. An
example
of
the
operation
of
4-20 mA reset in Heat mode is shown below.
Reset Type = Return (only for TGZ unit, Refrig = R134a)
Cooling Mode
The Active Cooling Leaving Water set point is adjusted based upon the difference
between the chiller’s entering and leaving evaporator water temperatures.
OM WGZC-1
35
The active cooling leaving water set point is reset using the following parameters:
1. Evaporator Leaving Water Temperature set point (Evap LWT)
2. Cooling Maximum Reset set point (Clg MaxRes)
3. Cooling Start Reset Delta Temperature (Clg StrtResDT)
4. Evaporator Delta Temperature (evaporator entering water temperature minus
leaving temperature)
Reset is accomplished by changing the Active Cooling Leaving Water set point from
the Evap LWT set point to the sum of Evap LWT (+) Cooling Maximum Reset set
points as the evaporator delta temperature (entering minus leaving) varies from the
Cooling Start Reset Delta T set point towards 0º F delta temperatures.
Heating Mode
The Active Heating Leaving Water set point is adjusted based upon the difference
between the chiller’s entering and leaving condenser water temperatures.
The active heating leaving water set point is reset using the following parameters:
1. Heating Leaving Water Temperature set point (Heat LWT)
2. Heating Maximum Reset set point (Htg MaxRes)
3. Heating Start Reset Delta Temperature (Htg StrtResDT)
4. Condenser Delta Temperature (condenser leaving water temperature minus
entering temperature)
Reset is accomplished by changing the Active Heating Leaving Water set point from
the Heat LWT set point to the value of [Heat LWT (-) Heating Maximum Reset set
points] as the condenser delta temperature (leaving minus entering) varies from the
Heating Start Reset Delta T set point towards 0ºF delta temperature.
Active LWT Set Point
The active LWT set point represents the current control set point based on unit mode
and reset. If unit mode is ice, then the active set point is equal to the ice set point. If
the unit mode is cool, the active set point is the cool set point plus the leaving water
reset value. If the unit mode is heat, the active set point is the heat set point minus the
leaving water reset value.
36
OM WGZC-1
LWT Error
LWT error compares the actual LWT to the active LWT set point.
The equation for cool mode is:
LWT error = LWT – active LWT set point
The equation for heat mode is:
LWT error = active LWT set point – LWT
LWT Slope
LWT slope is calculated such that the slope represents a time frame of one minute.
Every 12 seconds, the current LWT is subtracted from the value 12 seconds back. This
value is added to a buffer containing values calculated at the last five intervals. The
final result is a slope value that is an average over the past 60 seconds.
Pull Down Rate
The slope value calculated above will be a negative value as the water temperature is
dropping. For use in some control functions, the negative slope is converted to a
positive value by multiplying by –1.
Evaporator Saturated Temperature
Evaporator saturated temperature is calculated from the evaporator pressure for each
circuit.
R134a Evaporator Saturated Temperatures
When R134a refrigerant is selected the refrigerant pressure will be fitted to a curve
made up of 12 straight-line segments. The accuracy of calculated saturated
temperatures is +/- 0.5º F when compared to standard look up tables for R134a
refrigerant.
R22 Evaporator Saturated Temperatures
When R22 refrigerant is selected the refrigerant pressure will be fitted to a curve made
up of 12 straight-line segments. The accuracy of calculated saturated temperatures is
+/- 0.5º F when compared to standard look up tables for R22 refrigerant.
R407c Evaporator Saturated Temperatures
When R407c refrigerant is selected the saturated temperature is calculated from the
refrigerant pressure using a second order polynomial algorithm. For pressures less than
120 psi the calculated saturated temperature follows the dew point saturated
temperature. The accuracy of calculated saturated temperatures is +/- 1.0º F when
compared to standard lookup tables for R407c refrigerant
R410a Evaporator Saturated Temperatures
When R410a refrigerant is selected the refrigerant pressure will be fitted to a curve
made up of 24 straight-line segments. The accuracy of calculated saturated
temperatures are less than +/- 0.5°F when compared to standard look up tables for
R410a.
OM WGZC-1
37
Condenser Saturated Temperature
Condenser saturated temperature shall be calculated from the condenser pressure for
each circuit.
R134a Evaporator Saturated Temperatures
When R134a refrigerant is selected the refrigerant pressure will be fitted to a curve
made up of 12 straight-line segments. The accuracy of calculated saturated
temperatures is +/- 0.5º F when compared to standard look up tables for R134a
refrigerant.
R22 Condenser Saturated Temperature
When R22 refrigerant is selected the refrigerant pressure will be fitted to a curve made
up of 12 straight-line segments. The accuracy of calculated saturated temperatures is
+/- 0.5º F when compared to standard look up tables for R22 refrigerant.
R407c Condenser Saturated Temperature
When R407c refrigerant is selected the saturated temperature is calculated from the
refrigerant pressure using a second order polynomial algorithm. For pressures greater
than 120 psi the calculated saturated temperature follows the mid-point saturated
temperature. The mid-point saturated temperature is the average between the dew and
bubble point saturated temperatures. The accuracy of calculated saturated temperatures
is +/- 1.0º F when compared to standard lookup tables for R407c refrigerant
R410a Evaporator Saturated Temperatures
When R410a refrigerant is selected the refrigerant pressure will be fitted to a curve
made up of 24 straight-line segments. The accuracy of calculated saturated
temperatures are less than +/- 0.5°F when compared to standard look up tables for
R410a.
Evaporator Approach
The evaporator approach is calculated for each circuit.
For R134a, R22, and R410A refrigerant the equation is:
Evaporator Approach = LWT – Evaporator Saturated Temperature
For R407c refrigerant the equation is:
Evaporator Approach = LWT – Evaporator Saturated Temperature + 4.0º F
Suction Superheat
Suction superheat is calculated for each circuit using the following equation:
Suction superheat = Suction Temperature – Evaporator Saturated (Dew for R407c)
Temperature
Pumpdown Pressure
The pressure to which a circuit will pump down is based on the Low Evaporator
Pressure Unload set point. The equation is as follows:
Pumpdown pressure = Low evap pressure unload – 15 psi
The low limit for the calculated Pumpdown Pressure set point is 10.0 psi
38
OM WGZC-1
Unit Enable
The Unit Enable Set Point controls enabling and disabling the unit. The Unit Enable
Set Point has options of OFF and ON. The Unit OFF input, Remote input, keypad
entry, and BAS request can alter this set point. The Control Source Set Point
determines which sources can change the Unit Enable Set Point with options of
SWITCHES, KEYPAD or NETWORK.
Changing the Unit Enable Set Point is accomplished according to the following table.
NOTE: An “x” indicates that the value is ignored.
Unit Off
Input
Control Source
Set Point
Remote
Input
Keypad Entry
BAS
Request
Unit
Enable
OFF
X
x
x
x
OFF
x
SWITCHES
OFF
x
x
OFF
ON
SWITCHES
ON
x
x
ON
ON
KEYPAD
x
OFF
x
OFF
ON
KEYPAD
x
ON
x
ON
ON
NETWORK
x
x
OFF
OFF
ON
NETWORK
OFF
x
x
OFF
ON
NETWORK
ON
x
ON
ON
Unit Mode
The overall operating mode of the chiller is set by the Unit Mode Set Point with
options of COOL, COOL w/Glycol, ICE w/Glycol, and TEST. This set point can be
altered by the keypad, BAS, and Mode input. Changes to the Unit Mode Set Point are
controlled by two additional set points.
• Available Modes Set Point: Determines the operational modes available at any
time with options of COOL, COOL w/Glycol, COOL/ICE w/Glycol, ICE w/Glycol
and TEST
• Control Source Set Point: Determines the source that can change the Unit Mode
Set Point with options of KEYPAD, NETWORK, or SWITCHES.
When the Control source is set to KEYPAD, the Unit Mode shall stay at its previous
setting until changed by the operator. When the Control source is set to BAS, the most
recent BAS mode request shall go into effect even if it changed while the Control
source was set to KEYPAD or DIGITAL INPUTS.
Changing the Unit Mode Set Point can be accomplished according to the following
table.
NOTE: An “x” indicates that the value is ignored.
OM WGZC-1
Control Source
Set Point
Mode
Input
Keypad Entry
BAS
Request
X
X
x
x
X
x
x
x
SWITCHES
OFF
x
SWITCHES
ON
x
KEYPAD
x
COOL w/Glycol
Available Modes
Set Point
COOL
Unit Mode
COOL
COOL w/Glycol
COOL w/Glycol
x
COOL/ICE w/Glycol
COOL w/Glycol
x
COOL/ICE w/Glycol
ICE w/Glycol
x
COOL/ICE w/Glycol
COOL w/Glycol
KEYPAD
x
ICE w/Glycol
x
COOL/ICE w/Glycol
ICE w/Glycol
NETWORK
x
x
COOL
COOL/ICE w/Glycol
COOL w/Glycol
NETWORK
x
x
ICE
COOL/ICE w/Glycol
ICE w/Glycol
X
x
x
x
ICE w/Glycol
ICE w/Glycol
X
x
x
x
TEST
TEST
39
Unit Test Mode
The unit test mode allows manual testing of controller outputs. Entering this mode
requires the following conditions:
• Unit Switch = OFF
• Manager password active.
• Available Unit Mode set point = TEST
A test menu can then be selected to allow activation of the outputs. It shall be possible
to switch each digital output ON or OFF and set the analog outputs to any value.
Circuit Available
A circuit is available if the circuit switch is in the on position and no circuit alarms are
active. Timers that delay startup or staging of a circuit do not render it unavailable.
Power Up Start Delay
After powering up the unit, the motor protector modules may not reset for up to 150
seconds. After the control is powered up, no compressor can start for 150 seconds.
Motor protect inputs are ignored during this time so as to avoid tripping a false alarm.
Ice Mode Start Delay
An adjustable start to start ice delay timer will limit the frequency with which the
chiller may start in Ice mode. The timer starts when the first compressor starts while
the unit is in ice mode. While this timer is active, the chiller cannot restart in Ice mode.
The time delay is user adjustable.
The ice delay timer may be manually cleared to force a restart in ice mode. A set point
specifically for clearing the ice mode delay is available. In addition, cycling the power
to the controller will clear the ice delay timer.
Low Ambient Lockout
This feature is only available on air cooled units (WaterCooled=Off).
If the OAT drops below the low ambient lockout set point, then all running circuits will
do a normal stop. Once the lockout has been triggered, no compressors will start until
the OAT rises to the lockout set point plus 5°F.
Unit State
The Unit will always be in one of three states. These states are Off, Auto, and
Pumpdown. Transitions between these states are shown in the diagram on the
following page.
T1: Off to Auto
Unit Enable = True AND
No Unit Alarm AND
IF Unit Mode = Cir 1 Available OR Cir 2 Available
T2: Auto to Pumpdown
Keypad Enable = Off OR
BAS Enable = Off OR
Remote Switch = Off OR
T3: Pumpdown to Off
Unit Alarm OR
Unit Switch Off OR
No Compressors Running
T4: Auto to Off
Unit Alarm OR
Unit Switch Off OR
No Compressors Running AND [Unit Mode = Ice AND Ice Delay Active] OR
No Compressors Running AND [No Circuit Available]
40
OM WGZC-1
Unit State Diagram
Off
Power On
T3
Pumpdown
T1
T4
Auto
T2
Evaporator Water Pump State Control (Evap State)
The state-transition diagram shown below controls operation of the evaporator pump.
Evaporator Pump State Diagram
Off
Unit State = Off AND
No Evap Water Freeze Alarm
Unit State=Auto OR
Evap Water Freeze Alarm
Unit State = Off AND
No Evap Water Freeze Alarm
Run
[Evap Pump State = Start
AND Flow Switch Closed]
for time > Evap Recirc Tmr
Start
Pump Selection
The pump output used will be determined by the Evap Pump Control set point. The
setting allows the following configurations:
#1 only – Pump 1 will always be used.
#2 only – Pump 2 will always be used.
Auto – The primary pump is the one with the least run hours, the other is used as a
backup.
#1 Primary – Pump 1 is used normally, with pump 2 as a backup.
#2 Primary – Pump 2 is used normally, with pump 1 as a backup.
OM WGZC-1
41
Primary/Standby Pump Staging
The pump designated as primary will start first. If the evaporator state is start for a time
greater than the recirculate timeout set point and there is no flow, then the primary
pump will shut off and the standby pump will start. When the evaporator is in the run
state, if flow is lost for more than half of the flow proof set point value, the primary
pump will shut off and the standby pump will start. Once the standby pump is started,
the flow loss alarm logic will apply if flow cannot be established in the evaporator start
state, or if the flow is lost in the evaporator run state.
Auto Control
If auto pump control is selected, the primary/standby logic above is till used. When the
evaporator is not in the run state, the run hours of the pumps will be compared. The
pump with the least hours will be designated as the primary at this time.
Evaporator Water Flow Loss
The Evaporator Water Flow Loss logic allows the Unit to shutdown compressors on a
loss of flow up to two times every twenty-four hours before locking the unit out on a
Evaporator Flow Loss Alarm.
•
•
•
•
•
•
If there are no compressors running when Evaporator Water Flow Loss is indicated
the Unit Status changes to Auto:Wait for flow. The evaporator water pump state
changes to Start and no alarms are indicated.
If an Evaporator Water Flow Loss occurs while a compressor is running all of the
running compressors will be shutdown. The alarm indicators are turned On and the
Circuit Status for any circuit with running compressors becomes Off: Ready, the
Unit Status becomes Auto: Wait For Flow and the evaporator water pump state
changes to Start
When flow is reestablished the Unit Status becomes Auto: Recirculate while the
Evaporator Flow Recirculation Timer counts down. If there is continuous
evaporator water flow while the Evaporator Recirculation Timer counts down the
Alarm indicator is turned off, and the unit resumes normal start up procedures
based on water temperature and cycle timers.
If second Evaporator Water Flow Loss occurs within twenty-four hours the process
described above is repeated.
If a third loss of flow is indicated in a twenty-four hour time frame the unit will
shut down on an Evaporator Water Flow Loss alarm and it will be locked out until
this alarm is manually cleared.
The twenty-four hour timer that limits the auto restart is reset when the control
clock rolls over 00:00 each night.
Condenser Fans – Air Cooled
Air-cooled condenser fan control is active only when the water cooled set point is set to
off.
Fantrol
Fans 1, 3, 5, 7, 9, 11 are for circuit #1, and fans 2, 4, 6, 8, 10, 12 are for circuit 2. Fans
1 and 2 start with the first compressor on the respective circuit when the ambient
temperature is greater than 75°F. Below 75°F, these fans start when the condenser
saturated temperature gets up to the condenser saturated temperature target. The
compressor must be running in order to run any fans. R22 and R407C units are limited
to 8 fans.
42
OM WGZC-1
Fan Stages
There are 2, 3, 4, 5 or 6 fans available per circuit. On 8, 10, and 12 fan units, fans 5/7,
6/8, 9/11 and 10/12 are controlled by one contactor for each pair, using virtual stages to
allow a difference of only one fan between stages, See tables below:
4 and 6-Fan Remote Condenser
Stage
Fans Operating on Circuit 1
Fans Operating on Circuit 2
1
Fan 1
Fan 2
2
Fans 1 & 3
Fans 2 & 4
3
Fans 1, 3, 5
Fans 2, 4, 6
8-Fan Remote Condenser, R22, R407C
Stage
Fans Operating on Circuit 1
Fans Operating on Circuit 2
1
Fan 1
Fan 2
2
Fans 1, 3
Fans 2, 4
3
Fans 1, 3, 5
Fans 2, 6, 8
4
Fans 1, 3, 5, 7
Fans 2, 4, 6, 8
8-Fan Remote Condenser, R410A
Stage
Fans Operating on Circuit 1
Fans Operating on Circuit 2
1
Fan 1
Fan 2
2
Fans 1, 3
Fans 2, 4
3
Fans 1, 5, 7
Fans 2, 6, 8
4
Fans 1, 3, 5, 7
Fans 2, 4, 6, 8
10 Fan Remote Condenser, R410A
Stage
Fans Operating on Circuit 1
Fans Operating on Circuit 2
1
Fan 1
Fan 2
2
Fans 1, 3
Fans 2, 4
3
Fans 1, 5, 7
Fans 2, 6, 8
4
Fans 1, 3, 5, 7
Fans 2, 4, 6, 8
5
Fans 1, 3, 5, 7, 9
Fans 2, 4, 6, 8, 10
12Fan Remote Condenser, R410A
Stage
Fans Operating on Circuit 1
Fans Operating on Circuit 2
1
Fan 1
Fan 2
2
Fans 1, 3
Fans 2, 4
3
Fans 1, 5, 7
Fans 2, 6, 8
4
Fans 1, 3, 5, 7
Fans 2, 4, 6, 8
5
Fans 1, 3, 5, 7, 9
Fans 2, 4, 6, 8, 10
6
Fans 1, 3, 5, 7, 9, 11
Fans 2, 4, 6, 8, 10, 12
Normal Operation – Staging Up
At startup, the first fan will start when the saturated condenser temperature rises above
the target. After this, the stage up deadbands apply.
When the saturated condenser temperature is above the Target + the active deadband, a
Stage Up error is accumulated.
Stage Up Error Step = Saturated Condenser Refrigerant temperature – (Target + Stage
Up dead band)
OM WGZC-1
43
The Stage Up Error Step is added the Stage Up Accumulator once every Stage Up
Error Delay seconds. When Stage Up Error Accumulator is greater than the Stage Up
Error Set Point another stage is started.
When a stage up occurs or the saturated condenser temperature falls back within the
Stage Up dead band the Stage Up Accumulator is reset to zero.
Normal Operation – Staging Down
There are four Stage Down dead bands, one for each stage.
When the saturated condenser refrigerant temperature is below the condenser saturated
temperature target – the active dead band, a Stage Down error is accumulated.
Stage Down Error Step = (Target – Stage Down dead band) – Saturated Condenser
Refrigerant temperature
The Stage Down Error Step is added to Stage Down Accumulator once every Stage
Down Error Delay seconds. When the Stage Down Accumulator is greater than the
Stage Down Error Set Point another stage of condenser fans turn off. The last stage on
will not shut off until the circuit is in an off state.
When stage down occurs or the saturated temperature rises back within the Stage
Down dead band the Stage Down Error Accumulator is reset to zero.
Forced Fan Stage At Start
Fans may be started simultaneously with the compressor based on outdoor ambient
temperature. When the compressor starts, a Fantrol stage is forced based on the
following table.
OAT
Fantrol Stage At Start
>75°F
Forced Fan 1 SP
>90°F
Forced Fan 2 SP
>105°F
Forced Fan 3 SP
Up to four fans may be forced on when the compressor starts.
After forcing fans on, the saturated condenser temperature may temporarily stay below
the target by some amount. In order to keep the fans from staging off, no stage down
error can be accumulated until either the OAT drops below 75°F or the saturated
condenser temperature goes above the target.
Condenser Pump and Tower Control – Water Cooled
Condenser pump and cooling tower control logic requires that the unit be configured as
water-cooled in order to be active.
Condenser Water Pump State Control (Cond State)
If the unit is configured as water-cooled, then the state-transition diagram shown below
defines the condenser pump control logic.
44
OM WGZC-1
Condenser Pump State Diagram
Off
Cond Flow Alarm OR
Unit State = Off OR
Evap Pump State = Start OR
No Circuit Available OR
LWT error < Start Delta]
AND
No Cond Refrig Freeze Event
AND
No Compressor Running
Run
Unit State=Auto AND
Any Circuit Available AND
Stage up now = True]
OR
Cond Refrig Freeze Event
AND No Cond Flow Alarm
Cond Flow Alarm OR
[Unit State = Off OR
No Circuit Available OR
Evap Pump State = Start OR
LWT error < Start Delta]
AND
No Cond Refrig Freeze Event
AND
No Compressor Running
[Cond Pump State = Start
AND Flow Switch Closed]
for time > Cond Pmp
Recirc Time seconds
Start
Pump Selection
The pump output used will be determined by the Cond Pump Control set point. The
setting allows the following configurations:
#1 only – Pump 1 will always be used.
#2 only – Pump 2 will always be used.
Auto – The primary pump is the one with the least run hours, the other is used as a
backup.
#1 Primary – Pump 1 is used normally, with pump 2 as a backup.
#2 Primary – Pump 2 is used normally, with pump 1 as a backup.
Primary/Standby Pump Staging
The pump designated as primary will start first. If the condenser state is start for a time
greater than the re-circulate timeout set point and there is no flow, then the primary
pump will shut off and the standby pump will start. When the condenser is in the run
state, if flow is lost for more than half of the flow proof set point value, the primary
pump will shut off and the standby pump will start. Once the standby pump is started,
the flow loss alarm logic will apply if flow cannot be established in the condenser start
state, or if the flow is lost in the condenser run state.
Auto Control
If auto pump control is selected, the primary/standby logic above is till used. When the
condenser is not in the run state, the run hours of the pumps will be compared. The
pump with the least hours will be designated as the primary at this time
Condenser Water Flow Loss
The Condenser Water Flow Loss logic allows the Unit to shutdown compressors on a
loss of flow up to two times every twenty-four hours before locking the unit out on a
Condenser Flow Loss Alarm.
OM WGZC-1
45
•
•
•
•
•
•
If there are no compressors running when Condenser Water Flow Loss is indicated
the Unit Status changes to Auto:Wait for flow. The condenser water pump state
changes to Start and no alarms are indicated.
If a Condenser Water Flow Loss occurs while a compressor is running all of the
running compressors will be shutdown. The Alarm indicators are turned On and the
Circuit Status for any circuit with running compressors becomes Off: Ready, the
Unit Status becomes Auto: Wait For Flow and the condenser water pump state
changes to Start
When flow is reestablished the Unit Status becomes Auto: Recirculate while the
Condenser Flow Recirculation Timer counts down. If there is continuous
evaporator water flow while the Condenser Recirculation Timer counts down the
Alarm indicator is turned off, and the Unit resumes normal start up procedures
based on water temperature and cycle timers.
If second Condenser Water Flow Loss occurs within twenty-four hours the process
described above is repeated.
If a third loss of flow is indicated in twenty-four hour time frame the Unit will shut
down on an Condenser Water Flow Loss alarm and it will be locked out until this
alarm is manually cleared.
The twenty-four hour timer that limits the auto restart is reset when the control
clock rolls over 00:00 each night.
Tower Fans
Tower fan control is active when the unit is set up as water cooled (WaterCooled=On),
Tower Control is set to Temperature, and the condenser pump is in the RUN state.
Staging is based on Entering Condenser Water Temperature (ECWT). Operation
depends on the following parameters.
Condenser pump state
ECWT
Stage up and stage down timer values
Tower set points (Tower Control, Tower Stages, Stage Up Time, Stage Down Time,
Stage Differential ,Stage #1 ON, Stage #2 ON, Stage Down @, Stage Up @)
When the condenser pump starts, the stage up timer shall start. The first stage shall
turn ON when the following conditions are met:
The stage up timer completes
The ECWT is > Stage #1 ON set point
Bypass valve position is > the Stage Up @ set point (only if Valve/VFD Control set
point = Valve Stage)
Additional stages can turn on (up to the number specified by the Tower Stages set
point) when above conditions are met for the next stage plus the following condition:
VFD Speed is > the Stage Up @ set point (only if Valve/VFD Control set point =
VFD Stage OR Valve SP/VFD Stage)
Down staging shall occur when the following conditions are met:
The stage down timer completes
The ECWT is < Stage #X ON (Temp) set point – Stage Differential (Temp) set
point
Bypass valve position is < the Stage Down @ set point (only if Valve/VFD Control
set point = Valve Stage)
VFD Speed is < the Stage Down @ set point (only if Valve/VFD Control set point
= VFD Stage OR Valve SP/VFD Stage)
46
OM WGZC-1
Each stage up or stage down event will restart both the stage up and stage down timers.
Only one fan output will be switched at a time (except that all outputs switch OFF
when the condenser pump state equals OFF).
Cooling Tower Bypass Valve
When the Valve/VFD Control set point is set to None OR VFD Stage, this output will
be set to 0. Otherwise, it shall be controlled as described below.
Initial Valve Position
When the condenser pump is not in the RUN state, the valve output will be set as a
function of entering condenser water temperature (ECWT)) per the following graph.
Initial Valve Position
Max Position @
Set Point
(90°F)
(values are examples only)
Min Position @
Set Point
(60°F)
Min Start Position
Set Point (10%)
Max Start Position
Set Point (90%)
Operation After Start
When the condenser pump is in the RUN state, the valve output will be controlled in
one of two modes as specified by the Valve/VFD Control set point. The controlled
parameter will be the condenser entering water temperature. When the desired output
signal varies from 0 to 100%, the output voltage will vary as shown below.
0 to 10 VDC (Valve Type = NC to tower)
10 to 0 VDC (Valve Type = NO to tower)
Valve Set Point Mode
This mode is operational when the Valve/VFD Control set point is set to Valve Set
Point OR Valve SP/VFD Stage. In this mode the valve output is varied with a
proportional-derivative (PD) algorithm (with dead band) in order to maintain the
controlled parameter (CP) at the desired value. The output is always limited between
the Valve Control Range (Min) set point and the Valve Control Range (Max) set point.
A valve increment shall be computed once every 5 seconds according to the following
equation.
Increment = [(Error) * (Error Gain set point)] + [(Slope) * (Slope Gain set point)]
Where: Error = ECWT – Valve Set Point Slope = (Present CP) – (Previous CP)
When the Error is > the Valve Deadband set point, the valve position analog output (%
of full scale) is updated according to the following equation.
New %Position = Old %Position + Increment/10.
Valve Stage Mode
This mode is only operational when the Valve/VFD Control set point is set to Valve
Stage. In this mode the valve output is controlled as for Valve Set Point mode (above)
except that the active set point for the controlled parameter is selected according to the
following table.
Number Of Fans ON
0
1
2
OM WGZC-1
Active Set Point
Valve Set Point
Stage #1 ON
Stage #2 ON
47
Cooling Tower Fan VFD
When the Valve/VFD Control set point is set to None, Valve Setpoint, OR Valve Stage,
this output will be set to 0. Otherwise, it will be controlled in a manner identical to
Valve Stage Mode (above) except that (1) it will be kept at zero until the first fan stage
is ON and (2) the following set points do not apply.
Valve Control Range (Min)
Valve Control Range (Max)
Valve Type
Compressor Start/Stop Timing
This section determines when to start or stop a compressor. There are two separate
functions used, one for staging up and one for staging down.
Stage Up Now
The Stage Up Now flag is set based on the following tests:
If Unit mode = Cool AND
no compressors are running AND
LWT error > Start delta + 0.5 * Control Band AND
Motor Protect Timer expired AND
Stage up timer expired THEN
Stage Up Now = True
If Unit Mode = Cool AND
At least one compressor is running AND
LWT error > 0.5 * Control band AND
Pulldown rate <= Max pulldown rate AND
Compressors running < unit capacity limit AND
Stage up timer expired THEN
Stage Up Now = True
If Unit mode = Heat AND
no compressors are running AND
LWT error > Start delta + 0.5 * Control Band AND
Motor Protect Timer expired AND
Stage up timer expired THEN
Stage Up Now = True
If Unit Mode = Heat AND
At least one compressor is running AND
LWT error > 0.5 * Control band AND
Pulldown rate <= Max pulldown rate AND
Compressors running < unit capacity limit AND
Stage up timer expired THEN
Stage Up Now = True
48
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Stage Down Now
The Stage Down Now flag is set based on the following tests:
If Unit Mode = Cool AND
LWT error < -0.5 * Control band AND
More than one compressor running AND
Stage down timer expired THEN
Stage Down Now = True
If Unit Mode = Cool AND
LWT error < (-0.5 * Control band - stop delta) AND
One compressor running AND
Stage down timer expired THEN
Stage Down Now = True
If Unit Mode = Cool AND
Number of compressors running > Demand limit AND
Stage down timer expired THEN
Stage Down Now = True
If Unit Mode = Heat AND
LWT error < -0.5 * Control band AND
More than one compressor running AND
Stage down timer expired THEN
Stage Down Now = True
If Unit Mode = Heat AND
LWT error < (-0.5 * Control band - stop delta) AND
One compressor running AND
Stage down timer expired THEN
Stage Down Now = True
Compressor Sequencing
Compressor staging is based primarily on compressor run hours and starts.
Compressors that have less starts will normally start before those with more starts.
Compressors that have more run hours will normally shut off before those with less run
hours. In the event of a tie on number of starts, the lower numbered compressor starts
first. In the event of a tie on run hours, the lower numbered compressor shuts off first.
Run hours are compared in terms of tens of hours.
If possible, only one compressor per circuit will start before starting the second
compressor on any circuit. If a circuit is unavailable for any reason, the other circuit
shall be allowed to stage the second compressor on. When staging down, one
compressor on each circuit shall be left on until each circuit has only one compressor
running.
Low Ambient Start (WaterCooled = NO)
In order to avoid low evaporator pressure alarms at startup, low OAT start logic allows
for running at low evaporator pressures for a longer time than normal as well allowing
multiple compressor restart attempts before locking out the circuit.
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49
Low Ambient Start Procedure
A low OAT start is initiated if the condenser refrigerant saturated temperature is less
than 85.0°F when the first compressor starts. Once the compressor starts the circuit is
in a low OAT start state for a time equal to the Low OAT Start Time set point. During
Low OAT Starts, the freezestat logic and low evaporator pressure events are disabled.
The absolute limit for low evaporator pressure is enforced and the compressor will
shutdown if the evaporator pressure gets down to 5.0 psi. For R410a, the absolute limit
for low evaporator pressure is 20.0 psi.
When the Low OAT Start Timer has expired, if the evaporator pressure is greater than
or equal to the Low Evaporator Pressure Unload set point, the start is considered
successful and normal alarm and event logic is reinstated. If the evaporator pressure is
less than the Low Evaporator Pressure Unload set point when the Low OAT Start
Timer expires, the start is unsuccessful and the compressor will shutdown.
Three compressor restarts per circuit are allowed when a circuit fails to start a
compressor in a Low Ambient Start attempt. On the third failed Low Ambient Start
attempt the Restart Alarm is triggered and the circuit will not attempt to restart a
compressor until the Restart alarm has been cleared.
Circuit Capacity Overrides
The following conditions shall override the automatic capacity control when the chiller
is in cool mode only. These overrides keep a circuit from entering a condition in
which it is not designed to run.
Low Evaporator Pressure
If a compressor in a circuit is running and the evaporator pressure drops below the Low
Evaporator Pressure Hold set point, no more compressors will be allowed to start on
that circuit. The limit shall be active until the evaporator pressure reaches the hold Low
Evaporator Hold set point plus 8.0 psi for R134a, R22, and R407C or 13.0 psi for
R410A. On that circuit’s VIEW CIRCUITn (1) screen is displayed the “Hold Clear @”
value which is the limit by which the evaporator pressure must reach to allow for
additional loading. A Low Evaporator Pressure Hold event will be recorded in the
Event Log.
If two or more compressors are running in a circuit and the evaporator pressure drops
below the Low Evaporator Pressure Unload set point, the circuit will begin reducing
capacity. If two compressors are running, one of the compressors will be stopped after
a time delay has expired which is one-half the calculated freeze time (lower pressure
then shorter time). If three compressors are running, one compressor will stop after a
this time delay which is one-half the calculated freeze time and, ten seconds later, if the
pressure has not risen above the unload set point an additional compressor will be
stopped. The last compressor on a circuit will not stop due to the unload condition. The
low evaporator pressure unload event will clear when the evaporator pressure rises
either 8.0 psi for R134a, R22, and R407C or 13.0 psi for R410A above the Low
Evaporator Pressure Hold set point. A Low Evaporator Pressure Unload event will be
recorded in the Event Log.
If the evaporator pressure drops below the Low Evaporator Pressure Unload set point
and one compressor on the circuit is running then the following table applies.
50
Description
Low Evap Press Time
Requirement to continue
Check #1
15 seconds after start
Evap Press >(0.48*Low Evap Press SP)
Check #2
30 seconds after start
Evap Press >(0.66*Low Evap Press SP)
Check #3
45 seconds after start
Evap Press >(0.83*Low Evap Press SP)
Check #4
60 seconds after start
Evap Press > Low Evap Press SP
OM WGZC-1
High Condenser Pressure – Unload Logic
If the discharge pressure rises above the High Condenser Pressure Unload set point and
more than one compressor on the circuit is running, the circuit will stage down. One
compressor will shut down as soon as the pressure rises above the unload set point and
if two remain running then one more will shut down 10 seconds later if the pressure is
still above the unload set point. On that circuit’s VIEW CIRCUITn (1) screen is
displayed the “Hold Clear @” value which is the limit by which the condenser pressure
must drop to allow for additional loading. A High Condenser Pressure Unload event
will be recorded in the Event Log.
No stage up will be allowed on the circuit until the condenser pressure drops below the
unload set point less an offset value which is calculated based on 1) type refrigerant, 2)
number of compressors, 3) condenser configuration, and 4) how many high pressure
unload occurrences since the previous mid-night. See below for initial offset value and
step-increase for each additional occurrence.
Hold Clear Reset Value =
High Pressure Unload set point – [“Initial Offset” + [“Step-Increase” x [“number
of occurrence”-1]]]
Initial Offset & Step Increase
Condenser
Configuration
No. of
Compressors
Water-Cooled
Air-Cooled
R410A
R22,
R407C
R134a
Step
Increase
4
40 psi
30 psi
30 psi
10 psi
6
32 psi
N/A
20 psi
10 psi
4
100 psi
70 psi
N/A
15 psi
6
80 psi
N/A
N/A
15 psi
Example of Operation: Assume a packaged water-cooled WGZ unit with 4 compressors
using R410A as the refrigerant. Circuit number one is fully loaded (both compressors
running) when that circuit’s condenser pressure exceeds the High Condenser Pressure
Unload set point. Circuit number one will unload by turning one of the two compressors
off immediately. This circuit will not be allowed to load back up until its condenser
pressure decreases below the “Hold Clear @” value which is displayed on the “VIEW
CIRCUIT 1 (1)” screen. Since this is the first High Condenser Pressure – Unload
occurrence for that circuit, the circuit will be allowed to load once the condenser pressure
drops below the High Condenser Pressure Unload set point minus 40 psi. If using default
value (405 psi) this will be 365 psi. After some time, the condenser pressure is allowed to
decrease below this value and circuit number one is again allowed to load up. Again its
condenser pressure exceeds the High Condenser Pressure Unload set point and it unloads.
Because this is the second High Condenser Pressure – Unload occurrence for that circuit,
the circuit will not be allowed to load until the condenser pressure drops below the High
Condenser Pressure Unload set point minus 50 psig (40 psi plus step-increase10psi). If
using default values, this will be 355 psi. As you can see, for each occurrence the discharge
pressure must get lower and lower (based on Step-Increase value) before the circuit is
allowed to again load. This logic is intended to prevent excessive cycling of compressors.
Unit Capacity Overrides
The following conditions shall override the automatic capacity control when the chiller
is in cool mode only.
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51
Demand Limit
The maximum unit capacity can be limited by a 4 to 20 mA signal on the Demand
Limit analog input. This function is only enabled if the Demand Limit set point is set
to ON. The maximum unit capacity stage is determined as shown in the following
graph.
Limit Signal vs. Max Stage
(with 4 compressors)
Limit Signal vs. Max Stage
(with 6 compressors)
4
6
5
3
4
Max
Stage
Max
Stage
2
3
2
1
1
0
0
4.0
0
8.0
12.0
16.0
Limit Signal (mA)
25.0
50.0
75.0
20.0
4.0
6.7
9.3
12.0
14.7
17.3
20.0
83.4
100.0
Limit Signal (mA)
100.0
0
16.7 33.3
Limit Signal (%)
50.0
66.7
Limit Signal (%)
Any signal less than 4 mA does not limit the chiller capacity.
Network Limit
The maximum unit capacity can be limited by a network signal. This function is only
enabled if the unit control source is set to network. The maximum unit capacity stage
is based on the network limit value received from the BAS, and is determined as shown
in the following graph.
Network Limit vs. Max Stage
(with 4 compressors)
Network Limit vs. Max Stage
(with 6 compressors)
4
6
5
3
Max
Stage
Max
Stage
2
4
3
2
1
1
0
0
0
25.0
50.0
75.0
100.0
0
Network Limit (%)
16.7 33.3
50.0
66.7
83.4
100.0
Network Limit (%)
In order to allow all stages to run, a signal of 100.0% is required.
52
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Maximum LWT Rate
The maximum rate at which the leaving water temperature can drop is limited by the
Maximum Pull Down Rate set point when the unit mode is cool. If the rate exceeds
this set point, no more compressors shall be started until the pull down rate is less than
the set point. Running compressors will not be stopped as a result of exceeding the
maximum pull down rate.
Low Ambient Lockout (Water Cooled = NO Only)
If the OAT drops below the low ambient lockout set point, then all running circuits will
do a normal stop, after the compressors have stopped the evaporator water pump will
stop. Once the lockout has been triggered, the evaporator water pump will remain off
and no compressors will start until the OAT rises to the lockout set point plus 5°F.
Manual Compressor Control
The operator can manually enable and disable individual compressors. When a
compressor has been disabled it is considered unavailable to start in the staging logic.
With Manual Compressor control it is possible to take a damaged compressor offline
while the remaining compressors on the circuit can still provide some cooling.
A running compressor can not be disabled until it has been shutdown. If both of the
compressors on a circuit have been disabled then the circuit is disabled. If both circuits
have all of their compressors disabled, the Unit state will remain “Off”.
Normal Circuit Shutdown
If a condition arises that requires a circuit to shut down, but it is not an emergency
situation, then the circuit will do a pump down. A normal circuit shutdown will be
initiated when any of the following occur:
• Unit State = Pump Down
• Circuit Switch = Off
• Low Ambient Lockout
• A normal stage down occurs, and only one compressor on the circuit is running
• Unit mode = Ice AND the ice set point is reached
Pump Down Procedure
•
•
•
•
If both compressors are running, shut off the appropriate compressor based on
sequencing logic
With one compressor left running, turn off hot gas output and liquid line output
Keep running until evaporator pressure reaches the pump down pressure, then stop
compressor
If evaporator pressure does not reach pump down pressure within two minutes,
stop compressor and record a Failed Pumpdown event in the Event Log.
Rapid Circuit Shutdown
A situation may arise that requires a circuit to shut down immediately, without doing a
pumpdown. This rapid shutdown will be triggered by any of the following:
Unit State = Off
Circuit Alarm
Low ambient start attempt failed
All compressors, hot gas, and liquid line outputs should be turned off immediately for a
rapid shutdown.
OM WGZC-1
53
Liquid Line Solenoid
The liquid line output shall be on any time a compressor on the circuit is running and
the circuit is not performing a pump down. This output should be off at all other times.
Hot Gas Bypass Solenoid
This output shall be on when one compressor on the circuit is running and the circuit is
not performing a pump down. The output should be off at all other times including the
delay time described below.
The hot gas bypass valve opening will be delayed for Hot Gas Bypass Time set point
seconds (the default is 30 seconds) when the first compressor starts on each circuit.
EXV Control
The EXV control logic is active regardless of the expansion valve type setting. While a
circuit is in the run state, the EXV controls suction superheat. The superheat target is
8oF. PID logic will be used to control the superheat to the target value.
Any time the circuit is not in the run state, the EXV position should be 0.
EXV Control Range
The table below shows the EXV range based on the number of compressors running
and number of compressors on unit.
Number of
Compressors
4
Compressors Running
Valve
Position
1
2
3
EXV Min
8%
8%
-
EXV Max
60%
100%
-
EXV Min
8%
8%
8%
EXV Max
35%
45%
65%
6
Manual EXV Control
The EXV position can be set manually. Manual control can only be selected when
the circuit is in the run state. At any other time, the EXV control set point is forced
to auto.
When EXV control is set to auto, the manual EXV position setting follows the auto
control position. When EXV control is set to manual, the EXV position is equal to
the manual EXV position setting.
Maximum EXV Operating Pressure
This logic only applies to TGZ units (Refrig = R134a) equipped with electronic
expansion valves. The purpose of this logic is to prevent the operating circuit’s
evaporator pressure from exceeding the ‘MaxOpPress’ set point (found on “SET
COMP SPs (6) screen) and overloading the compressors. The electronic expansion
valves (EEV) will close to prevent the operating circuit’s evaporator pressure from
exceeding the ‘MaxOpPress’ set point.
54
OM WGZC-1
Using the Controller
Getting Started
There are two basic procedures to learn in order to utilize the MicroTech II controller:
•
Navigating through the menu matrix to reach a desired menu screen and knowing
where a particular screen is located.
•
Knowing what is contained in a menu screen and how to read that information or
how to change a setpoint contained in the menu screen.
Navigating Through the Menus
The menus are arranged in a matrix of screens across a top horizontal row. Some of
these top-level screens have sub-screens located under them. The general content of
each screen and its location in the matrix are shown in Figure 10. (A detailed
description of each menu begins on page 58.) There are two ways to navigate through
the menu matrix to reach a desired menu screen.
One is to scroll through the matrix from one screen to another using the four ARROW
keys.
The other way is to use shortcuts to work through the matrix hierarchy. From any
menu screen, pressing the MENU key will take you to the top level of the hierarchy.
The display will show ALARM, VIEW, and SET as shown in Figure 8. This
corresponds to the second row of screens on Figure 10. One of these groups of screens
can then be selected by pressing the key connected to it via the pathway shown in
Figure 8 on page 19.
For example, selecting ALARM will go the next row of menus under ALARM
(ALARM LOG or ACTIVE ALARM). Selecting VIEW will go the next level of
screens under VIEW (VIEW UNIT STATUS or VIEW UNIT TEMP). Selecting SET
will go to a series of screens for looking at and changing setpoints.
After pressing the MENU button, the top-level menu screen will show:
< ALARM
< VIEW
<
SET
<
After pressing the “VIEW” menu button, a menu screen will show:
VIEW
< COMPRESSOR
<
UNIT
< EVAPORATOR
<
FANS
After pressing the “EVAPORATOR” menu button, the selected data screen will show:
VIEW EVAP
(screen data)
(screen data)
(screen data)
The arrow keys will automatically return to the “scroll” mode at this time.
OM WGZC-1
55
MENU Key
The MENU key is used to switch between the shortcut method (known as the MENU
mode and as shown in Figure 8) and scrolling method (known as the SCROLL mode).
The MENU mode is the shortcut to specific groups of menus used for checking
ALARMS, for VIEWING information, or to SET setpoint values. The SCROLL mode
allows the user to move about the matrix (from one menu to another, one at a time) by
using the four ARROW keys. A typical menu screen is shown in the following figure.
Pressing the MENU key from any menu screen will automatically return you to the
MENU mode.
Figure 9, Display in the Shortcut (SCROLL) Mode and Keypad Layout
MENU Key
Air Condit ioning
VIEW UNIT STATUS
Unit = COOL
Compr. #1/#2=OFF/OFF
Evap Pump = RUN
ARROW
ENTER Key
Keys
ENTER Key
Pressing the ENTER key changes the function of the ARROW keys to the editing
function as shown below:
LEFT key Default, changes a value to the factory-set default value.
RIGHT key Cancel, cancels any change made to a value and returns to the original
setting.
UP key
Increment, increases the value of the setting
DOWN key Decrement decreases the value of a setting.
These four edit functions are indicated by one-character abbreviation on the right side of
the display (this mode is entered by pressing the ENTER key).
Most menus containing setpoint values have several different setpoints shown on one
menu. When in a setpoint menu, the ENTER key is used to proceed from the top line
to the second line and on downward. The cursor will blink at the entry point for
making a change. The ARROW keys (now in the edit mode) are used to change the
setpoint as described above. When the change has been made, press the ENTER key to
enter it. Nothing is changed until the ENTER key is pressed.
For example, to change the chilled water setpoint:
1.
2.
3.
4.
Press MENU key to go to the MENU mode.
Press SET (the UP Key) to go to the setpoint menus.
Press UNIT SPs (the Right key) to go to setpoints associated with unit operation.
Press the DOWN key to scroll down through the setpoint menus to the third menu
which contains Evap LWT=XX.X°F.
5. Press the ENTER key to move the cursor down from the top line to the second line
in order to make the change.
6. Use the ARROW keys (now in the edit mode as shown above) to change the setting.
7. When the desired value is achieved, press ENTER to enter it and also move the
cursor down.
56
OM WGZC-1
At this point, the following actions can be taken:
1. Change another setpoint in this menu by scrolling to it with the ENTER key.
2. Using the ENTER key, scroll to the first line in the menu. From there the ARROW
keys can be used to scroll to different menus.
Menu Screens
Various menus are shown in the controller display. Each menu screen shows specific
information, in some cases menus are only to view status of the unit, in some cases for
checking alarms, and in some cases they are used to set setpoint values that can be
changed.
The menus are arranged in a matrix of screens across a top horizontal row. Some of
these top-level screens have sub-screens located under them. The content of each
screen and its location in the matrix are shown in Figure 10. A description of each
menu begins on page 58.
The arrow keys on the controller are used to navigate through the menus. The keys are
also used to change numerical setpoint values contained in certain menus.
Figure 10, Menu Matrix
“MENU”
“VIEW” MENUS
UNIT
CIRCUITS
VIEW UNIT VIEW UNIT
FANS
EVENTS
VIEW
VIEW
VIEW
REFRIGERANT
VIEW
VIEW
VIEW
EVENT (1)
STATUS
TEMP
CIRC #1
CIRC #2
REFRIGERANT
REFRIGERANT
FAN/TOWER
(1)
(1)
STATUS
STATUS
CIRCUIT #1
CIRCUIT #2
(1)
(1)
(1)
(1)
(1)
VIEW UNIT VIEW UNIT
VIEW
VIEW
VIEW EVAP
VIEW EVAP
VIEW
STATUS
TEMP
COMP #1
CIRC #2
(2)
(2)
FAN/TOWER
(5)
(2)
STATUS
STATUS
(3)
(3)
VIEW
EVENT (n)
(n)
⇐ Continued ⇐
(Right side of matrix continued from above)m
“ALARM” MENUS
“SET” MENUS
ALARM LOG
ACTIVE ALARM (1)
SET UNIT
SET COMP
SET LIMIT
(LAST)
TYPE, TIME
SPs, (1)
SPs (1)
ALARMS (1)
TYPE, TIME
TEST
SET FANS (1)
SET
TEST
STAGES
TOWER
UNIT (1)
FANTROL
(1)
ALARM LOG
ACTIVE ALARM (2)
SET UNIT SPs,
SET COMP
SET LIMIT
SET FANS (2)
SET
(NEXT TO LAST)
TYPE, TIME
(2)
SPs
ALARMS (2)
STAGE ON
TOWER
ALARM LOG
ACTIVE ALARM (3)
SET UNIT SPs,
SET LIMIT
SET FANS (3)
SET
(SECOND TO
CLEAR/VIEW
(3)
ALARMS (3)
STAGE OFF
TOWER
ADDITIONAL
(2)
LAST)
(2)
(3)
ALARM LOG
SET UNIT SPs,
SET TOWER
TEST
LAST 25 SHOWN
(4)
(to n)
UNIT (7)
(to 13)
Selection can be made within the matrix by using the LEFT/RIGHT keys to move
between columns and the UP/DOWN keys to move between rows.
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57
Menu Descriptions
This section contains information on each screen. The menu screens are in order of the
matrix in Figure 10 going from left to right and down when there are sub-menus. Many
menus are self-explanatory. A Setpoint menu allows selection of whether the unit has a
water-cooled condenser, WaterCooled = Y (Yes) or a remote condenser, WaterCooled =
N (No). This selection will alter some menus as appropriate to the type of condenser.
Screen Definitions – MENU
Top level menu:
< ALARM
< VIEW
<
SET
<
ALARM menu:
ALARM
< ACTIVE
<
LOG
<
<
VIEW menu:
VIEW
< COMPRESSOR
<
UNIT
< EVAPORATOR
< FANS/TOWER
VIEW UNIT menu:
VIEW
<
TEMP
UNIT
<
STATUS
< REFRIGERANT
SET menu:
SET <
ALARM LIMITS
<
UNIT SPs
< COMPRESSOR SPs
< FANS/TOWER SPs
Screen Definitions – VIEW
View Unit Status
VIEW UNIT STATUS (1)
Auto
Cooling Stage = 0
Evap Pump = RUN
Unit states can be OFF, COOL, GYLCOL, ICE, or ALARM as determined from the
Unit Mode setpoint, the Unit Enable, and the presence of an alarm.
Circuit states can be OFF/OFF, ON/OFF, OFF/ON, and ON/ON.
Evaporator Pump States can be OFF, STRT, or RUN.
When more than one screen are stacked (i.e., relate to each other on the same subject),
they are numbered sequentially with the numbers appearing in the upper-right corner.
58
OM WGZC-1
VIEW UNIT STATUS (2)
Demand Limit=Stg 4
Network Limit=Stg 4
VIEW UNIT STATUS (3)
Stg Up Delay=XXX sec
Stg Dn Delay=XXX sec
Ice Delay=XXh XXm
VIEW UNIT STATUS (4)
D.O.
111111111
123456789012345678
000000000000000000
This menu gives the status of digital outputs (D.O.), 1=ON, 0=OFF. Numbers are 1
through 18. See Error! Reference source not found. on page Error! Bookmark not
defined. for number reference.
VIEW UNIT STATUS (5)
D.I.
111111111
123456789012345678
000000000000000000
This menu gives the status of digital inputs (D.I.), 1=ON, 0=OFF. Numbers are 1
through 18. See Table 6 on page 20 for number reference.
VIEW UNIT STATUS (6)
Analog Output
(volts x 100)
1 = 000.0 2 =
000.0
VIEW UNIT STATUS (7)
Analog Output
(volts x 100)
3 = 000.0 4 =
000.0
VIEW UNIT STATUS (8)
EXB1 Online
D.O. 1 2 3 4
0 0 0 0
View Unit Tempertures
OM WGZC-1
Water Cooled = Y
TGZ in Cool Mode
Water Cooled = N
VIEW UNIT TEMP (1)
Evap LWT = XX.X°°F
Cond EWT = XXX.X°°F
LWT Target = XX.X°°F
VIEW UNIT TEMP (1)
Evap LWT
= XX.X°°F
OAT = XXX.X°°F
LWT Target = XX.X°°F
59
TGZ Unit in Heat Mode (R134a)
VIEW UNIT TEMP (1)
Evap LWT = XX.X°°F
Cond EWT = XXX.X°°F
LWT Target = XX.X°°F
The difference between the three screens above is that water-cooled units and the TGZ
units will give the entering condenser water temperature and air-cooled units will give
the outside air temperature (OAT). The outside-air temperature sensor is furnished
with the unit, inside the control panel, wired to the correct terminals. It must be
installed outdoors in a location that will give the true outdoor temperature that the
condenser coils will see. Splicing of the sensor lead may be required. The unit will not
operate without the sensor installed.
WGZ unit
TGZ Unit (R134a)
VIEW UNIT TEMP (2)
LWT Pulldn= XX.X °F
Control Band= XX.X°°F
VIEW UNIT TEMP (2)
LWT Pulldn= XX.X °F
Control Band= XX.X°°F
VIEW UNIT TEMP (3)
Control Temps
Start Up XX.X°°F
Stage Up XX.X°°F
VIEW UNIT TEMP (4)
Control Temps
Stage Down XX.X°°F
Shut Down
XX.X°°F
TGZ Unit Only in Cool Mode
TGZ Unit Only in Heat Mode
VIEW UNIT TEMP (5)
Cond LWT
XX.X°°F
Evap EWT
XX.X°°F
VIEW UNIT TEMP (5)
Cond LWT
XX.X°°F
Evap EWT
XX.X°°F
View Circuit
VIEW CIRCUIT#1
OFF
VIEW CIRCUIT#1
Comp 1
= OFF
Hours = XXXXX
Starts = XXXXX
60
(1)
(2)
OM WGZC-1
VIEW CIRCUITt#1 (3)
Comp 3
= OFF
Hours = XXXXX
Starts = XXXXX
If # of Compresors = 6
Only f or R410A or R134a
VIEW CIRCUIT 1
Comp5=Off
Hours = XXXXX
Starts = XXXXX
(4)
VIEW CIRCUIT 2
Off
(1)
VIEW CIRCUIT#2
Comp 2
= OFF
Hours = XXXXX
Starts = XXXXX
(2)
VIEW CIRCUIT#2
Comp 4
= OFF
Hours = XXXXX
Starts = XXXXX
(3)
If # of Compresors = 6
Only f or R410A or R134a
VIEW CIRCUIT 1
Comp6=Off
Hours = XXXXX
Starts = XXXXX
(4)
View Refrigerant
VIEW REFRG Cir 1 (1)
Evap Press XXX.X psi
Cond Press XXX.X psi
R 134a, R22, R410A
VIEW REFRG Cir 1 (2)
Sat Evap XXX.X °F
Sat Cond XXX.X °F i
OM WGZC-1
R407C
VIEW REFRG Cir 1 (2)
Evap Dew
XXX.X °F
Cond. Mid
XXX.X °F
61
VIEW REFRG Cir 1 (3)
SuctionTemp=XXX.X°°F
Surperheat = XXX.X°°F
EvapApproach= XX.X°°F
TGZ Only (R134a)
VIEW REFRG Cir 1 (4)
LiqLineTemp=XXX.X°°F
Subcooling = XXX.X°°F
CondApproach= XX.X°°F
Units with EEV only
VIEW REFRG Cir 1 (5)
EXV Ctrl = XXX
EXV Pos = XXX.X%
SH Target = XX.X°°F
TGZ Units Only (R134a)
VIEW REFRG Cir 1 (6)
EXV Ctrl Range
XX.X% ---XX.X%
VIEW REFRG Cir 2 (1)
Evap Press XXX.X psi
Cond Press XXX.X psi
R 134a, R22, R410A
VIEW REFRG Cir
Sat Evap XXX.X
Sat Cond XXX.X
2 (2)
°F
°F i
R407C
VIEW REFRG Cir 2 (2)
Evap Dew
XXX.X °F
Cond. Mid
XXX.X °F
VIEW REFRG Cir 2 (3)
SuctionTemp=XXX.X°°F
Surperheat = XXX.X°°F
EvapApproach= XX.X°°F
TGZ Only (R134a)
VIEW REFRG Cir 2 (4)
LiqLineTemp=XXX.X°°F
Subcooling = XXX.X°°F
CondApproach= XX.X°°F
62
OM WGZC-1
Units with EEV only
VIEW REFRG Cir 2 (5)
EXV Ctrl = XXX
EXV Pos = XXX.X%
SH Target = XX.X°°F
TGZ Units Only (R134a)
VIEW REFRG Cir 2 (6)
EXV Ctrl Range
XX.X% ---XX.X%
Water Cooled = Y Only or
TGZ Unit (R134a)
VIEW TOWER (1)
Stages ON = 1 of 2
EntCondTemp = XXX °F
Setpoint = XXX °F
The first Stages ON value is the number of fan stages ON. The second number is the
Tower Stages setpoint (0 if Tower Control = None). This screen shows the number of
tower fans “on” for each circuit. This screen will show the fans “on” whether they are
actually connected to and controlled by the MicroTech II controller or not.
Water Cooled = Y Only or
TGZ Unit (R134a)
VIEW TOWER (2)
Bypass Valve = XXX%
VFD Speed
= XXX%
The Bypass Valve value shall be “None” (in place of XXX%) if the Valve/VFD Control
setpoint = None or VFD Stage. The VFD Speed value shall be “None” if the
Valve/VFD Control setpoint = None, Valve Setpoint, or Valve Stage.
Water Cooled = N Only
VIEW FANS (1)
Fans On Circuit#1 =XX
Fans On Circuit#2 =XX
This screen shows the number of air-cooled condenser fans “on” for each circuit. This
screen will show the fans “on” whether they are actually connected to and controlled
by the MicroTech II controller or not.
VIEW FANS
Stg Error Up
Cir 1 =
XXX
Cir 2 =
XXX
OM WGZC-1
(2)
Down
XXX
XXX
63
VIEW FANS
(3)
Sat Cond Target =
XXX.X
Screen Definitions – ALARM
ALARM ACTIVE (X)
Time
Date
Alarm Description
OR
ALARM ACTIVE (X)
No more alarms
Press ENTER to clear
all active alarms
If the unit is off on a shutdown alarm or running, but in a limit alarm condition, the
cause and date will appear in the upper screen. If there is a simultaneous occurrence of
more than one alarm, the others will appear in additional screens below the first one,
accessed by the DOWN ARROW.
Either type alarm will light a red light in back of the LEFT-ARROW KEY. The light
will go out when the fault is cleared. To clear the fault, scroll down to the last screen
and press ENTER. If other faults have appeared, they will all be cleared at the same
time. It is not necessary to have a password open to clear alarms.
ALARM LOG (X)
Alarm Description
Time
Date
Data Edit and scroll
The last 25 alarms, either shutdown or limit, are shown in this menu and subsequent
menus located under it. ARROW DOWN from this menu will go to the next-to-last
alarm, ARROW DOWN again will go to the second from last, and so on through the
last 25 occurrences. The screens are numbered (1), (2), (3), etc.
Screen Definitions – EVENT LOG
EVENT LOG (X)
Event Description
Time
Date
Screen Definitions – SET
Set Unit Setpoints
SET UNIT SPs (1)
Unit Enable = OFF
Unit Mode
= COOL
Source = KEYPAD
Unit Enable settings can be OFF and ON as determined from the Unit Enable setpoint.
Unit Enable is an external signal or a keypad setting that keeps the unit off when the
setting is OFF and allows it to run if there is a call for cooling when the setting is ON.
The source for the signal is selected in the 4th line and can be:
•
64
KEYPAD, in which case the selection is made in line 2 and would be normally
selected as ON. This is the normal setting when no external signals are controlling
the unit.
OM WGZC-1
•
SWITCHES, in which an external switch is wired across terminals #40 and #53.
(See wiring diagram page 8 or 9.)
•
NETWORK, used with BAS signal, which is wired to the three communication
ports.
•
Unit Mode settings can be
•
COOL, normal setting used with chilled water air-condition applications.
•
COOL w/GLYCOL, used with low temperature, glycol applications. It allows a
lower LWT setpoint to be used.
•
ICE w/GLYCOL, used with ice storage systems, allows changing from chilled
glycol operation to lower temperature ICE operation. In ICE, the unit runs at full
load until the ICE setpoint is reached, at which time the unit shuts off. A threeposition switch wired to terminals #28 and #38 initiates the change from glycol
cooling to making ice. (See wiring diagrams on page 8 or 9.)
Unit Mode settings can be COOL COOLw/Glycol, or ICEw/Glycol, as determined
from the Unit Mode setpoint.
Source settings can be KEYPAD, SWITCHES, or NETWORK as determined from the
Mode Source setpoint.
SET UNIT SPs
(2)
Available Modes
=COOL
Set w/Unit Switch Off
SET UNIT SPs
(3)
Evap LWT = XX.X°°F
Ice LWT = XX.X°°F
EvapDeltaT= XX.X°°F
SET UNIT SPs
(4)
Start Delta= XX.X°°F
Stop Delta= XX.X°°F
Demand Limit = ON
See page 14 for an explanation of compressor staging.
WGZ Units Only
SET UNIT SPs
(5)
Max Pulldn=X.X°°F/min
Evap Recirc= XXX sec
Evap Pump = #1 Only
TGZ Units Only (R134a)
SET UNIT SPs
(5)
Max Pulldn=X.X°°F/min
Evap Recirc= XXX sec
Evap Pump = #1 Only
Evap Pump choices are; #1 Only, #2 Only, Auto, #1 Primary, #2 Primary.
OM WGZC-1
65
Water-Cooled = ON
SET UNIT SPs
(6)
Water Cooled = ON
Cond Recirc=XXX sec
Cond Pump = #1 Only
Water-Cooled = OFF
SET UNIT SPs
(6)
Water Cooled = Off
LowAmbLock XXX.X °F
TGZ Units (R134a)
SET UNIT SPs
(6)
Water Cooled = Off
LowAmbLock XXX.X °F
Water Cooled = On is the setting for units with on-board water-cooled condensers.
Pump choices are; #1 Only, #2 Only, Auto, #1 Primary, #2 Primary.
WaterCooled = OFF is used for units with remote condensers, usually air cooled.
SET UNIT SPs
(7)
Ice Time Delay=Xxsec
Clear Ice Delay=No
H.G. Delay = XX sec
H.G. Delay, hot gas bypass delay, keeps the hot gas solenoid valve closed when the first
compressor on a circuit starts. This delay allows sufficient condenser pressure to build
up.
SET UNIT SPs
(8)
CLOCK
dd/mmm/yyyy
hh:mm:ss
SET UNIT SPs
(9) SET UNIT SPs
(9)
Units = °F/psi
Units = °F/psi
Lang = ENGLISH
Lang = ENGLISH
Refrig = None
Refrig = R22
SET UNIT SPs
(9)
Units = °F/psi
Lang = ENGLISH
Refrig = R407C
SET UNIT SPs
(9) SET UNIT SPs
(9)
Units = °F/psi
Units = °F/psi
Lang = ENGLISH
Lang = ENGLISH
Refrig = R410A
Refrig = R134a
Refrigerant type is factory-set.
SET UNIT SPs
(10)
Protocol = Modbus
Ident Number=001
Baud Rate=9600
BAS interface settings, available mid-2003.
66
OM WGZC-1
SET UNIT SPs
(11)
Evap Press Sensor
Cir 1 Offset XX.X psi
Cir 2 Offset XX.X psi
The pressure offsets on menus 11 and 12 and the temperature offsets on menus 10, 11
and 12 correct the controller's display of the parameters. The sensors used in these
units have a high degree of repeatability but may need correction (offset). An accurate
pressure gauge or thermometer is used to determine the correct temperature or
pressure. A positive or negative offset value is then entered to make the controller
reading agree with the measured value.
SET UNIT SPs
(12)
Cond Press Sensor
Cir 1 Offset XX.X psi
Cir 2 Offset XX.X psi
SET UNIT SPs
(13)
Evap Leaving Water
Temperature Sensor
Offset= 00.0 oF
SET UNIT SPs
(13)
LWT Sensors
Evap Offset = 00.0 oF
Cond Offset = 00.0 °F
SET UNIT SPs
(14)
OAT/Cond Lvg Water
Temperature Sensor
Offset= 00.0 oF
TGZ Units (Refrig = R134a)
SET UNIT SPs
(14)
LWT Sensors
Evap Offset = 00.0 oF
Cond Offset = 00.0 °F
SET UNIT SPs
(15)
Suction Temp Sensor
Cir1 Offset 00.0 °F
Cir2 Offset 00.0 °F
OM WGZC-1
WGZ Unit (R22,R407C,R410A)
SET UNIT SPs
(16)
Clg ResType = X
Clg MaxRes = XX.X ºF
TGZ Unit (Refrig = 134a)
SET UNIT SPs
(16)
Liq Line Temp Sensors
Circ1 Offset = 00.0 ºF
Circ2 Offset = 00.0 ºF
WGZ Unit (R22,R407C,R410A)
SET UNIT SPs
(17)
ENTER PASSWORD: XXXX
Active Password
Level: None
TGZ Unit (Refrig = 134a)
SET UNIT SPs
(17)
Clg ResType = X
Clg MaxRes = XX.X ºF
Clg StrtRes = XX.X ºF
67
TGZ Unit in Cooling Mode .
SET UNIT SPs
(17)
ENTER PASSWORD: XXXX
Active Password
Level: None
TGZ Unit in Heat Mode.
SET UNIT SPs
(17)
Htg ResType = X
Htg MaxRes = XX.X ºF
Htg StrtRes = XX.X ºF
TGZ Unit Heat Mode.
SET UNIT SPs
(18)
ENTER PASSWORD: XXXX
Active Password
Level: None
Two four-digit passwords provide OPERATOR and MANAGER levels of access to
changeable parameters. The passwords are preprogrammed into the controller. Either
password must be entered using the ENTER PASSWORD (12) screen before a
protected setting can be changed. The operator password is 0100. The manager level
is 2001.
This screen can be accessed either through the SET OTHER menu or by simply
pressing the ENTER key while on one of the SET screens. The controller will
automatically go from the screen with the setting change to this screen. After the
correct password has been entered, the controller will automatically return to the
original set screen.
Once a password has been entered, it remains valid for 15 minutes after the last keypress.
Set Compressor Setpoints
SET COMP SPs
(1)
# of Compressors = X
Stop-Start =XXmin
Start-Start =XXmin
This menu sets the anti-recycle timers. Stop-Start is the time required before starting a
compressor after it has stopped. Start-Start is the time required before starting a
compressor after the last time it has started. It is recommended that the default values
of 5 minutes and 15 minutes not be changed.
SET COMP SPs
(2)
InterStgUp =XXXsec
InterStgDown= XXsec
Clear Cycle Tmr = NO
InterStageUp is the time delay since the last stage change before a compressor can
stage on, default is 120 sec.
68
OM WGZC-1
InterStageDn is the time delay since the last stage change before a compressor can
stage off normally (not by an alarm). Default is 30 sec. It is recommended that these
settings not be changed.
# of Compressors = 4
# of Compressors = 6
SET COMP SPs
(3)
Comp 1 = Enable
Comp 3 = Enable
# of Compressors = 4
SET COMP
Comp 1 =
Comp 3 =
Comp 5 =
SPs
(3)
Enable
Enable
Enable
# of Compressors = 6
SET COMP SPs
(4)
Comp 2 = Enable
Comp 4 = Enable
SET COMP
Comp 2 =
Comp 4 =
Comp 6 =
SPs
(4)
Enable
Enable
Enable
Enable screens #3 and #4 require the manager password to change.
TGZ Units Only (R134a)
SET COMP SPs
Expansion Valve
Type = Thermal
(5)
SET COMP SPs
(5)
Expansion Valve
Type = Electronic
MaxOpPress=XXX.X psi
Expansion Valve Type = Electronic
SET COMP SPs
(6)
Cir 1 EXV
EXV Control = Auto
Manual EXV Pos=XXX.X
Expansion Valve Type = Electronic
SET COMP SPs
(7)
Cir 2 EXV
EXV Control = Auto
Manual EXV Pos=XXX.X
SET ALARM LIMITS
SET ALARM LMTS (1)
Low EVAP Pressure
Hold=XXXpsi
Unload=XXXpsi
The Hold and Unload have the same default value of 59 psi. If two compressors are
running, the LowEvPrUnld is in effect and the lag compressor will be shut off to
unload the unit. If one compressor is running, the LowEvPrHold is in effect and the
lag compressor is prevented from starting, thereby holding the unit capacity.
The last action to take place is the shutoff of all compressors running when the
LowEvPrStop setting is reached (default is 58 psi). Reducing these time intervals will
increase detrimental compressor cycling. It is recommended that these settings not be
changed.
OM WGZC-1
69
SET ALARM LMTS (2)
High Cond Pressure
Unload= XX.X°°F
Stop=XXXsec
Unload is a limit alarm that unloads the unit at 370 psi in an attempt to prevent total
shutdown from the HighCondPr at 380 psi. The stage down is set at 370 psi. It is
recommended that these settings not be changed.
Stop (the unit high-discharge-pressure shutdown) is a stop alarm that shuts off the unit
when the discharge pressure reaches the setting. The default setting is 380 psi.
LowEvPrDelay is a time delay on the low pressure trip that reduces nuisance lowpressure trips. The default setting is 30 seconds.
SET ALARM LMTS (3)
GroundFault = N
PhaseVoltage = N
Low OATStartTMR=XXsec
GroundFault and PhaseVoltage entries are Y (Yes) or N (No) depending on whether the
options are on the unit.
CondFreeze is an alarm that reduces the chance of freezing the water in the condenser
(when compressors are not running). An alarm is registered and the condenser pump is
energized at the same time. The alarm setpoint is 34°F saturated condenser
temperature and it resets at +2°F above the setpoint.
SET ALARM LMTS (4)
Evap Freeze = XX.X°°F
EvapFlowProff=XXXsec
Recirc Timeout=XXmin
Evap Freeze (the unit freeze protection shutdown) is actually a stop alarm and shuts off
the unit when the LWT reaches 36°F. It is cleared by going to the CLEAR ALARM
menu in the ACTIVE ALARM hierarchy.
EvapFlowProof is the flow switch interlock. Closing the flow switch and therefore
proving the existence of chilled water flow resets this trip. It is recommended that
these settings not be changed.
LowAmbientLock applies to units with air-cooled condensers and prevents unit
operation below the setting. The available range is -2°F to 60°F with a default of 35°F.
WaterCooled=ON
SET ALARM LIMITS (5)
Cond Freeze= XX.X °F
CondFlowProof= XX sec
TGZ in Heat Mode
SET ALARM LIMITS (6)
LowSourceTmp = XX.X°°F
LowSourceDif = XX.X°°F
70
OM WGZC-1
Set Air-Cooled Condenser Fans
Water-cooled = Off
SET FANS SPs
Fan Stages=X
Speedtrol=Yes/No
(1)
Water-cooled = Off
SET FANS SPs
(2)
Stage ON Deadband (°°F)
Stg2
Stg3
Stg4
XXX
XXX
XXX
Water-cooled = Off
SET FANS SPs
(3)
Stage Off Deadband (°°F)
Stg2
Stg3
Stg4
XXX
XXX
XXX
The SET FANS SP screens 2 through 5 establish the temperature that will stage the
condenser fans on and off. These screens apply only to units set up for use with aircooled condensers (WaterCooled=No). On such units, the settings do not have to be
entered if the unit controller is not used to stage condenser fans for head pressure
control. If the MicroTech II unit controller is not used to control the fans, some other
method must be used.
Water cooled=Off
SET FANS SPs
(4)
Cond Sat Temp Target
Set Point= XXX.X °F
Water cooled=Off
SET FANS SPs
(5)
# Fans On At Startup
>75°F >90°F >105°F
X
X
X
Set Cooling Tower Control
The MicroTech II controller is capable of controlling cooling tower water temperature
on chillers using water-cooled condensers. Output wiring connection points are shown
on the field wiring diagrams.
[Water Cooled = Y] - Condenser Pump on with first Compressor on. Tower fan control
is active when the Tower Control setpoint is set to Temperature and the condenser
pump is in the RUN state. Staging is based on Entering Condenser Water Temperature
(ECWT). Operation depends on the following parameters.
Condenser pump state
ECWT OR Lift pressure
Stage up and stage down timer values
OM WGZC-1
71
Tower setpoints (Tower Control, Tower Stages, Stage Up Time, Stage Down Time,
Stage Differential, Stage #1 ON, Stage #2 ON, Stage Down @, Stage Up @)
When the condenser pump starts, the stage up timer shall start. The first stage shall
turn ON when the following conditions are met:
The stage up timer completes
The ECWT is > Stage #1 ON setpoint
Bypass valve position is > the Stage Up @ setpoint (only if Valve/VFD Control
setpoint = Valve Stage)
Additional stages can turn on (up to the number specified by the Tower Stages setpoint)
when above conditions are met for the next stage plus the following condition:
VFD Speed is > the Stage Up @ setpoint (only if Valve/VFD Control setpoint =
VFD Stage OR Valve SP/VFD Stage)
Down staging shall occur when the following conditions are met:
The stage down timer completes
The ECWT is < Stage #X ON (Temp) setpoint – Stage Differential (Temp) setpoint
point
Bypass valve position is < the Stage Down @ setpoint (only if Valve/VFD Control
setpoint = Valve Stage)
VFD Speed is < the Stage Down @ setpoint (only if Valve/VFD Control setpoint =
VFD Stage OR Valve SP/VFD Stage)
Each stage up or stage down event shall restart both the stage up and stage down
timers. Only one fan output shall be switched at a time (except that all outputs switch
OFF when the condenser pump state equals OFF).
Water-cooled On
SET TOWER SPs (1)
Tower Control= None
Tower Stages = X
StageUP/DN=XXX/XXX%
When Tower Control is None the control of condenser water temperature is not by the
MicroTech II controller and assumed to be furnished elsewhere.
Tower Stages is the number of tower fans to be staged by the controller, choices are 0,
1, or 2. "0" indicates control will be by a bypass valve or variable speed pump
controlled by the MicroTech II controller.
StageUP/DN imposes a time delay between fan stages when turning on or turning off.
Water-cooled On
SET TOWER SPs (2)
Stage ON (Temp)°°F
#1 #2
XXX XXX
Stage ON Temp is the entering condenser water temperature (ECWT) that will turn on
tower fan #1 and #2. Default settings are 70°F and 75°F. Cold condenser water will
improve unit efficiency but too cold can cause erratic operation. Settings below 60°F
are not recommended.
72
OM WGZC-1
Water-cooled On
SET TOWER SPs (3)
StageDiff = XX.X°°F
Stage Up Tmr=XX min
StageDn Tmr=XX min
StageDiff is the number of degrees below the Stage ON that will turn off the tower
fans. For example, if Stage ON #1 is 70°F and StageDiff is 5°F, tower fan #1 will stage
off when the ECWT drops to 65°F and stage the fan on when the ECWT rises to 70°F.
The same is true for fan #2.
Stage Up timer is the number of minutes that must elapse between the condenser pump
starting (it starts with the unit) and fan #1 starting or the time between fan #1 starting
and fan #2 starting.
StageDown is the elapsed time between staging down the fan motors.
Water-cooled = Y
SET TOWER SPs (4)
Valve/VFD Control=
ValveSP/VFDStage
Valve Type=NC to Twr
Valve/VFD Control settings are None, Valve Setpoint, Valve Stage, VFD Stage, or
ValveSP/VFDStage. Default is None which results in no control of the tower from the
MicroTech II controller.
Valve Setpoint, the valve will control (bypass tower) to hold the minimum temperature
as established by the Set Tower SPs in screen (5) below.
This mode is operational when the Valve/VFD Control setpoint is set to Valve Setpoint
OR Valve SP/VFD Stage. In this mode the valve output is varied with a proportionalderivative (PD) algorithm (with deadband) in order to maintain the controlled
parameter (CP) at the desired value. The output is always limited between the Valve
Control Range (Min) setpoint and the Valve Control Range (Max) setpoint. A valve
increment shall be computed once every 5 seconds according to the following equation.
(Error Gain and Slope Gain are set in menu screen #8.)
Increment = [(Error) * (Error Gain setpoint)] + [(Slope) * (Slope Gain setpoint)]
Where: Error = ECWT – Valve Setpoint
Slope = (Present CP) – (Previous CP)
When the Error is > the Valve Deadband setpoint, the valve position analog output
(% of full scale) is updated according to the following equation.
New %Position = Old %Position + Increment/10
Valve Stage, controls from the fan stage setpoint in use. It is recommended that the
Valve Setpoint method explained above be used rather than this mode.
This mode is only operational when the Valve/VFD Control setpoint is set to Valve
Stage. In this mode the valve output is controlled as for Valve Setpoint mode (above),
except that the active setpoint for the controlled parameter is selected according to the
following table.
# Of Fans ON
0
1
2
3
4
OM WGZC-1
Active Setpoint
Valve Setpoint
Stage #1 ON
Stage #2 ON
Stage #3 ON
Stage #4 ON
73
VFD Stage, ValveSP/VFDStage, When the Valve/VFD Control setpoint is set to None,
Valve Setpoint, OR Valve Stage, this output is set to 0. Otherwise, it will be controlled
in a manner identical to Valve Stage Mode (above) except that (1) it shall be kept at
zero until the first fan stage is ON, and (2) the following setpoints do not apply.
Valve Control Range (Min)
Valve Control Range (Max)
Valve Type
Valve Type settings are NC (normally closed to tower) or NO (normally open).
These settings establish the operation of a tower bypass valve (must be a 3-way valve).
Initial Valve Position
When the condenser pump is not in the RUN state, the valve output shall be set as a
function of entering condenser water temperature (ECWT) per the following graph.
Figure 11, Initial Valve Position
Initial Valve Position
Max Position @
Setpoint
(90°F)
(values are examples only)
Min Position @
Setpoint
(60°F)
Min Start Position
Setpoint (10%)
Max Start Position
Setpoint (90%)
Operation After Start
When the condenser pump is in the RUN state, the valve output shall be controlled in
one of two modes as specified by the Valve/VFD Control setpoint. The controlled
parameter shall be the condenser entering water temperature. When the desired output
signal varies from 0 to 100%, the output voltage shall vary as shown below.
0 to 10 VDC (Valve Type = NC)
10 to 0 VDC (Valve Type = NO)
Water-cooled = Y
SET TOWER SPs (5)
Valve SP = XXX °F
Valve DB = XX.X °F
Valve SP is the minimum tower water temperature acceptable, default is 65°F.
Valve DB is the dead-band in degrees, default is 2.0°F.
74
OM WGZC-1
Water-cooled = Y
SET TOWER SPs (6)
ValveStartPosition
Min = XXX% @XXX°°F
Max = XXX% @XXX°°F
The ValveStartposition is the position of the valve when the unit starts. Default for
minimum start position is 0%, and 100% for maximum position.
Water-cooled = Y
SET TOWER SPs (7)
Valve Control Range
Min = XXX%
Max = XXX%
Defaults are 10% minimum and 90% maximum.
Water-cooled = Y
SET TOWER SPs (8)
PD Control Loop
Error Gain = XX
Slope Gain = XX
Defaults are 25 for both error and slope.
TEST
The test screens are only available when the unit is in TEST mode. Using these
screens, any digital output can be controlled manually.
R22, R407C
R410A
TEST UNIT
(1)
Alarm Signal =OFF
Evap Pump 1 = OFF
TEST UNIT
(1)
Alarm Signal =OFF
Evap Pump 1 = OFF
Evap Pump 2 = OFF
# of Compressors = 4
# of Compressors = 6
TEST UNIT
(2)
Liq Line Sol #1= OFF
CompressorHG1 = OFF
1= OFF 3= OFF
TEST UNIT
Liq Line Sol #1=
Compressor HG1 =
1= OFF 3= OFF 5=
# of Compressors = 4
# of Compressors = 6
TEST UNIT
(3)
Liq Line Sol #2=OFF
Compressor HG2 = OFF
2= OFF 4= OFF
TEST UNIT
(3)
Liq Line Sol #2=OFF
Compressor HG2 = OFF
2= OFF 4= OFF 6= OFF
Water Cooled = ON
TEST UNIT
(4)
Cond Pump 1 = OFF
Cond Pump 2 = OFF
TwrFan1=OFF Fan2=OFF
OM WGZC-1
(1)
OFF
OFF
OFF
Water Cooled = OFF
TEST UNIT
(4)
Fan 1=OFF Fan 3=OFF
Fan 5/7=OFF
Fan 9=OFF
75
Water Cooled = ON
Water Cooled = OFF
TEST UNIT
(5)
Twr Bypass= XXX.X %
Twr VFD=
XXX.X %
TEST UNIT
(5)
Fan 2=OFF Fan 4=OFF
Fan 6/8=OFF
Fan 10=OFF
TEST UNIT
(6)
EXV Cir 1= XXX.X %
EXV Cir 2= XXX.X %
Editing Review
Editing shall be accomplished by pressing the ENTER key until the desired field is
selected. This field shall be indicated by a blinking cursor under it. The arrow keys
shall then operate as defined below.
CANCEL (Right) Reset the current field to the value it had when editing began.
DEFAULT (Left)
Set value to original factory setting.
INCREMENT (Up) Increase the value or select the next item in a list.
DECREMENT (Down) Decrease the value or select the previous item in a list.
During edit mode, the display shall show a two-character wide menu pane on the right
as shown below.
SET UNIT SPs (X)
(data)
(data)
(data)
<D
<C
<+
<-
Additional fields can be edited by pressing the ENTER key until the desired field is
selected. When the last field is selected, pressing the ENTER key switches the display
out of “edit” mode and returns the arrow keys to “scroll” mode.
Alarms
When an alarm occurs, the alarm type, limit value (if any), date, and time are stored in
the active alarm buffer corresponding to that alarm (viewed on the Alarm Active
screens) and also in the alarm history buffer (viewed on the Alarm Log screens). The
active alarm buffers hold a record of the last occurrence of each alarm and whether or
not it has been cleared. The alarm can be cleared by pressing the Edit key. A separate
buffer is available for each alarm (High Cond Pressure, Evaporator Freeze Protect,
etc.). The alarm history buffer holds a chronological account of the last 25 alarms of
any type.
Security
Two four-digit passwords provide OPERATOR and MANAGER levels of access to
changeable parameters.
Either password can be entered using the ENTER
PASSWORD screen which can be accessed either through the SET OTHER menu or
by simply pressing the ENTER key while on one of the SET screens. The password
can then be entered by pressing the ENTER key, scrolling to the correct value with the
UP and DOWN arrow keys, and pressing ENTER again. Once the correct password
has been entered, the previously selected screen will reappear. Once a password has
been entered, it will remain valid for 15 minutes after the last key-press.
76
OM WGZC-1
BAS Interface
The BAS interface will use the supervisor port on the controller as a connection point.
Protocols Supported
The following building automation system (BAS) protocols are supported. It is
possible to change the building automation interface without loading different
software.
BACnet
When protocol is set to BACnet, the baud rate and ident set points are not accessible.
The ident setting is locked at 1 for BACnet, and the baud rate is locked to 19200.
LONworks
With protocol set to LON, the baud rate and ident set points are not accessible. The
ident setting is locked at 1 for LON, and the baud rate is locked to 4800.
Modbus
With the protocol set to Modbus, the baud rate and ident set points are accessible.
Available Parameters
Types: A = Analog, I= Integer, D= Digital
I/O: I = Input only, O = Output only , I/O = Input/Output
Type
Index
I/O
Description
LONWORKS
BACnet
Modbus
A
1
I/O
Network Cool LWT set point
x
x
x
A
2
O
Active LWT set point
x
x
x
A
3
I/O
Network limit set point
x
x
x
A
6
O
Evap LWT
x
x
x
A
7
O
Cond EWT
x
x
x
A
10
O
Unit capacity (%)
x
x
x
A
11
I
Network Cool LWT set point default
x
A
15
O
Suction temp
x
x
x
A
16
O
Evap sat temp
x
x
x
A
17
O
Evap pressure
x
x
x
A
20
O
Cond sat temp
x
x
x
A
21
O
Cond pressure
x
x
x
A
39
O
OAT
x
x
x
A
42
O
Active Capacity Limit
x
x
x
A
50
I/O
Network Ice LWT set point
x
x
x
I
1
O
Active alarms 1
x
x
x
I
2
O
Active alarms 2
x
x
x
I
3
O
Active alarms 3
x
x
x
I
4
O
Active alarms 4
x
x
x
I
5
O
Active alarms 5
x
x
x
I
6
O
Active alarms 6
x
x
x
I
7
O
Active alarms 7
x
x
x
I
8
O
Active alarms 8
x
x
x
I
9
O
Active alarms 9
x
x
x
I
10
O
Active alarms 10
x
x
x
Continued next page.
OM WGZC-1
77
Table continued
78
Type
Index
I/O
Description
LONworks
BACnet
Modbus
I
11
O
I
12
O
Active alarms 11
x
x
x
Active alarms 12
x
x
I
13
x
O
Active alarms 13
x
x
x
I
14
O
Active alarms 14
x
x
x
I
15
O
Active alarms 15
x
x
x
I
16
O
Active alarms 16
x
x
x
I
17
I
Network chiller mode set point
x
x
x
I
18
O
LON Chiller run mode
x
I
19
O
Active chiller mode
x
x
x
I
20
I
Network demand limit default set
point
x
I
21
I
Network chiller mode default set point
x
I
22
O
Sequence Status
Bit 1 – Unit Full Load Flag
Bit 2 – Circuit One Available Flag
Bit 3 – Circuit Two Available Flag
x
x
x
I
28
O
Unit model type, refrigerant
x
x
x
I
29
O
Unit language
x
x
x
I
30
O
Unit software version
x
x
x
I
32
I
Compressor select
x
x
x
I
35
I/O
Clock year
x
x
I
36
I/O
Clock month
x
x
I
37
I/O
Clock day of month
x
x
I
38
I/O
Clock day of week
x
x
I
39
I/O
Clock hours
x
x
I
40
I/O
Clock minutes
x
x
I
45
O
Compressor starts
x
x
I
46
O
Compressor run hours
x
x
D
1
I/O
Network chiller enable set point
x
x
x
D
2
O
Chiller enable status
x
x
x
D
3
O
Active alarm indicator
x
x
x
D
4
O
Chiller run enabled
x
x
x
x
x
x
D
5
O
Chiller local control
x
D
6
O
Chiller capacity limited
x
x
x
D
7
O
Evap flow
x
x
x
D
8
O
Cond flow
x
x
x
D
9
I
Network chiller enable default set
point
x
D
10
I
Ignore network defaults
x
D
24
I
Network clear alarm signal
x
x
x
OM WGZC-1
Optional Controls
Phase/Voltage Monitor (Optional)
The phase/voltage monitor is a device that provides protection against three-phase
electrical motor loss due to power failure conditions, phase loss, and phase reversal.
Whenever any of these conditions occur, an input relay is deactivated, disconnecting
power to the thermostatic control circuit. The compressor does a rapid shutdown
including a pump down cycle.
The input relay remains deactivated until power line conditions return to an acceptable
level. Trip and reset delays have been provided to prevent nuisance tripping due to
rapid power fluctuations.
When three-phase power has been applied, the input relay should close and the “run
light” should come on. If the relay does not close, perform the following tests.
1. Check the voltages between L1-L2, L1-L3, and L2-L3. These voltages should be
approximately equal and within +10% of the rated three-phase line-to-line voltage.
2. If these voltages are extremely low or widely unbalanced, check the power system
to determine the cause of the problem.
3. If the voltages are good, turn off the power and inter-change any two of the supply
power leads at the disconnect switch.
This may be necessary, as the phase/voltage monitor is sensitive to phase reversal. Turn
on the power. The relay should now close after the appropriate delay.
Factory settings are as follows:
Voltage Setting, set at nameplate voltage.
Trip Delay Time, 2 seconds
Restart Delay Time, 60 seconds
Hot Gas Bypass (Optional)
This option allows passage of discharge gas to the evaporator, permitting operation at
lower loads than available with compressor unloading. It also keeps the velocity of
refrigerant gas high enough for proper oil return at light load conditions.
The pressure regulating valve is a Sporlan SHGBE-8 and factory set to begin opening
at 69 psig and can be changed by changing the pressure setting. The adjustment range
is 0 to 100 psig. To raise the pressure setting, remove the cap on the bulb and turn the
adjustment screw clockwise. To lower the setting, turn the screw counterclockwise. Do
not force the adjustment beyond the range it is designed for, as this will damage the
adjustment assembly. The regulating valve opening point can be determined by slowly
reducing the system load while observing the suction pressure. When the bypass valve
starts to open, the refrigerant line on the evaporator side of the valve will begin to feel
warm to the touch.
WARNING
The hot gas line can become hot enough to cause personal injury in a
very short time; care should be taken during valve checkout.
OM WGZC-1
79
Troubleshooting Chart
PROBLEM
1.
2.
1.
2.
Thermal overloads tripped or fuses
blown.
Defective contactor or coil.
System shut down by equipment
protection devices.
3.
6.
7.
8.
No cooling required.
Liquid line solenoid will not open.
Motor electrical trouble.
6.
7.
8.
9.
Loose wiring.
9.
3.
Compressor Will
Not Run
POSSIBLE CAUSES
Main switch, circuit breakers open.
Fuse blown.
4.
5.
4.
5.
Flooding of refrigerant into crankcase.
Compressor
Noisy or Vibrating
Improper piping support on suction or
liquid line.
Worn compressor.
Condenser water insufficient or
temperature too high.
Replace.
Readjust temperature control or water
regulating valve. Investigate ways to
increase water supply.
Clean.
Fouled condenser tubes (water-cooled
condenser). Clogged spray nozzles
(evaporative condenser). Dirty tube and
fin surface (air cooled condenser).
Noncondensables in system.
System overcharge with refrigerant.
Discharge shutoff valve partially closed.
Condenser undersized (air-cooled).
High Discharge
Pressure
High ambient conditions.
Faultly condenser temp. regulation.
Insufficient refrigerant in system.
Low suction pressure.
Low Discharge
Pressure
Condenser too large.
Low ambient conditions.
Excessive load.
High Suction
Pressure
5.
Expansion valve overfeeding.
Lack of refrigerant.
Evaporator dirty.
Clogged liquid line filter-drier.
Clogged suction line or compressor
suction gas strainers.
Expansion valve malfunctioning.
6.
Condensing temperature too low.
6.
7.
Compressor will not unload.
7.
8.
1.
2.
Insufficient water flow.
Clogged suction oil strainer.
Excessive liquid in crankcase.
8.
3.
4.
3.
4.
Low oil level.
Flooding of refrigerant into crankcase.
5.
6.
1.
2.
3.
4.
Low Suction
Pressure
1.
2.
3.
4.
5.
Little or No Oil
Pressure
80
POSSIBLE CORRECTIVE STEPS
Close switch
Check electrical circuits and motor
winding for shorts or grounds.
Investigate for possible overloading.
Replace fuse or reset breakers after
fault is corrected.
Overloads are auto reset. Check unit
closely when unit comes back on line.
Repair or replace.
Determine type and cause of shutdown
and correct it before resetting protection
switch.
None. Wait until unit calls for cooling.
Repair or replace coil.
Check motor for opens, short circuit, or
burnout.
Check all wire junctions. Tighten all
terminal screws.
Check superheat setting of expansion
valve.
Relocate, add or remove hangers.
EPA purge the noncondensables.
Remove excess refrigerant.
Open valve.
Check condenser rating tables against
the operation.
Check condenser rating tables against
the operation.
Check condenser control operation.
Check for leaks. Repair and add charge.
See corrective steps for low suction
pressure below.
Check condenser rating table against the
operation.
Check condenser rating tables against
the operation.
Reduce load or add additional
equipment.
Check remote bulb. Regulate superheat.
Check for leaks. Repair and add charge.
Clean chemically.
Replace cartridge(s).
Clean strainers.
Check and reset for proper superheat.
Replace if necessary.
Check means for regulating condensing
temperature.
See corrective steps for failure of
compressor to unload.
Adjust flow.
Clean.
Check crankcase heater. Reset
expansion valve for higher superheat.
Check liquid line solenoid valve
operation.
Add oil.
Adjust thermal expansion valve.
OM WGZC-1
PROBLEM
Compressor
Loses Oil
POSSIBLE CAUSES
Lack of refrigerant.
Velocity in risers too low (A-C only).
Oil trapped in line.
Low voltage during high load conditions.
Motor Overload
Relays or Circuit
Breakers Open
Compressor
Thermal Switch
Open
Freeze Protection
Opens
Defective or grounded wiring in motor or
power circuits.
Loose power wiring.
High condensing temperature.
Power line fault causing unbalanced
voltage.
High ambient temperature around the
overload relay
Operating beyond design conditions.
Discharge valve partially shut.
Thermostat set too low.
Low water flow.
Low suction pressure.
POSSIBLE CORRECTIVE STEPS
Check for leaks and repair. Add
refrigerant.
Check riser sizes.
Check pitch of lines and refrigerant
velocities.
Check supply voltage for excessive line
drop.
Replace compressor-motor.
Check all connections and tighten.
See corrective steps for high discharge
pressure.
Check Supply voltage. Notify power
company. Do not start until fault is
corrected.
Provide ventilation to reduce heat.
Add facilities so that conditions are within
allowable limits.
Open valve.
Reset to 42°F (6°C) or above.
Adjust flow.
See “Low Suction Pressure.”
Warranty Statement
Limited Warranty
Consult your local McQuay Representative for warranty details. Refer to Form 933430285Y. To find your local McQuay Representative, go to www.mcquay.com.
OM WGZC-1
81
This document contains the most current product information as of this printing. For the most up-todate product information, please go to www.mcquay.com.
All McQuay equipment is sold pursuant to McQuay’s Standard Terms and Conditions of Sale and
Limited Product Warranty. Consult your local McQuay Representative for warranty details. Refer to
form 933-430285Y-00-A (09/08). To find your local representative, go to www.mcquay.com
(800) 432-1342 • www.mcquay.com
OM WGZC-1 (6/09)