Water-Cooled Scroll Compressor Chillers Operating Manual

Operating Manual

OM WGZ-2

Water-Cooled Scroll Compressor Chillers

Group: Chiller

Part Number: 331374501

Effective: March 2005

Supercedes: OM WGZ-1

WGZ 030AW To WGZ 120AW, Packaged Water-Cooled Chiller

WGZ 030AA To WGZ 120AA, Chiller with Remote Condenser

30 to 120 Tons, 105 to 420 kW

Software Version WGZD20102C

60 Hz, R-22, R-407C

Table of Contents

Introduction........................................3

General Description............................... 3

Nomenclature ........................................ 3

Water Pressure Drop.............................. 3

Operating Limits.................................... 6

Components........................................... 6

Unit Configuration ............................7

Field Wiring Diagrams .......................... 8

Control Panel Layout .......................... 10

Motor Protection Module .................... 10

Start-Up and Shutdown................... 11

Pre Start-up.......................................... 11

Start-up ................................................ 11

Weekend or Temporary Shutdown ...... 12

Start-up after Temporary Shutdown .... 12

Extended Shutdown............................. 12

Start-up after Extended Shutdown ...... 13

Low Ambient Start .............................. 13

Fan High Ambient Rapid Start ............ 14

Sequence of Operation ....................14

Start-up/Compressor Staging............... 14

MicroTech II Controller ................. 18

Controller Software Version................ 18

General Description............................. 18

Setpoints .............................................. 21

Protection (Shutdown) Alarms ............ 22

Event (Limit) Alarms........................... 23

Staging Parameters .............................. 26

Capacity Overrides .............................. 26

Digital Output Control ........................ 27

Analog Output Control........................ 28

Using the Controller ............................ 31

Menu Screens ...................................... 34

Menu Descriptions .............................. 34

Optional Controls ............................ 51

Phase/Voltage Monitor (Optional) ...... 51

Hot Gas Bypass (Optional) ................. 51

Troubleshooting Chart......................... 52

Warranty Statement ........................ 53

2

Manufactured in an ISO Certified facility

"McQuay" is a registered trademark of McQuay International

©2005 McQuay International

Illustrations and data cover McQuay International products at the time of publication and we reserve the right to make changes in design and construction at anytime without notice.

WGZ 030A through 120A OM WGZ-2

Introduction

General Description

McQuay Type WGZ water chillers are designed for indoor installations and are available with watercooled condensers (Model AW), or arranged for use with remote air-cooled or evaporative condensers

(Model AA). Each water-cooled unit is completely assembled and factory wired before evacuation, charging and testing. They consist of hermetic scroll compressors, brazed-plate evaporator, watercooled condenser (WGZ-AW), and complete refrigerant piping.

Units manufactured for use with remote condensers (Models WGZ-AA) 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, filterdriers, 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.

The compressors are not fused as standard, but can be protected by optional circuit breakers or fuses, or can rely on a field-installed, fused disconnect switch for protection.

BOOT & BIOS

BOOT Version: 3.0F BIOS 3.56

Manuals: Information in unit initial installation and routine maintenance is contained in Installation and Maintenance Manual IMM WGZ-2.

Nomenclature

W G Z 100 - A W

Water-Cooled

W = Water-Cooled Condenser

A = Unit Less Condenser

Global

Design Vintage

Scroll Compressor

Nominal Capacity (Tons)

Water Pressure Drop

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.

Minimum Part Load Flow Rates: This full load design minimum flow is not to be confused with the part load minimum flow rate that must be maintained for chillers operating in variable primary flow pumping systems. As chiller capacity drops, the flow rate is reduced proportionally. See the following table for the part load minimum flow rates.

Table 1, Minimum Part Load Flow Rates

030 035 040 045 050 055 060 070 080 090 100 110 120

Min.Part Load GPM 30 33 38 43 47 53 58 67 74 83 91 102 113

OM WGZ-2 WGZ 030A through 120A 3

4

10

9

8

7

6

5

4

3

Figure 1, Evaporator Pressure Drop, WGZ 030 – WGZ 120

1.9

2.5

3.2

3.8 4.4 5.0 5.7 6.3

Flow Rate (L/s)

12.6

18.9

25.2

31.5

37.9

44.2

40 120

30 90

20

WGZ 030

WGZ 040

WGZ 050

WGZ 060

WGZ 080

60

WGZ 100 - 120

30

27

24

21

18

15

12

9

2 6

WGZ 035

WGZ 070

WGZ 055

WGZ 090

WGZ 045

1 3

30 40 50 60 70 80 90 100 200

Flow Rate (GPM)

300 400 500 600 700

WGZ

Model

Minimum Flow Nominal Flow Maximum Flow

Inch-Pound S.I. Inch-Pound S.I. Inch-Pound S.I.

GPM Ft. L/S kPa GPM Ft. L/S kPa GPM Ft. L/S kPa

030

035

040

045

050

055

060

070

080

090

100

110

120

45.5 1.85 2.87 5.54 75.8 5.15 4.78 15.40 126.3 14.31 7.97 42.77

50.3 1.76 3.17 5.27 83.8 4.90 5.29 14.65 139.7 13.62 8.81 40.70

57.7 1.83 3.64 5.46 96.2 5.07 6.07 15.15 160.3 14.08 10.12 42.10

63.7 1.71 4.02 5.10 106.1 4.74 6.69 14.17 176.8 13.16 11.16 39.35

70.0 1.70 4.41 5.08 116.6 4.72 7.36 14.12 194.3 13.12 12.26 39.21

78.2 1.70 4.93 5.08 130.3 4.72 8.22 14.10 217.2 13.11 13.70 39.17

85.8 1.67 5.41 5.00 143.0 4.65 9.02 13.90 238.3 12.91 15.04 38.60

97.9 1.75 6.18 5.24 163.2 4.87 10.30 14.54 272.0 13.51 17.16 40.40

112.3 1.86 7.09 5.56 187.2 5.17 11.81 15.45 312.0 14.36 19.68 42.92

123.5 1.91 7.79 5.70 205.9 5.29 12.99 15.82 343.2 14.71 21.65 43.96

134.9 2.14 8.51 6.39 224.9 5.94 14.19 17.74 374.8 16.49 23.65 49.29

152.9 2.75 9.65 8.21 254.9 7.63 16.08 22.79 424.8 21.18 26.80 63.31

168.8 3.34 10.65 9.99 281.3 9.29 17.75 27.76 468.8 25.80 29.58 77.11

Note: Minimum, nominal, and maximum flows are at a 16

°F, 10°F, and 6°F chilled water temperature range respectively and at ARI tons.


70

60

Figure 2, Condenser Pressure Drop, WGZ 030 – WGZ 120

1.9

2.5

3.2

3.8 4.4 5.0 5.7 6.3

Flow Rate (L/s)

12.6

18.9

25.2

31.5

37.9

44.2

210

180

50

150

40

WGZ 050, 055

WGZ 080

WGZ 090

WGZ 040, 045

120

30 90

20 60

WGZ 030, 035

10

9

8

7

6

5

4

WGZ 100 - 120

30

27

24

21

18

15

12

3

9

WGZ 070

WGZ 060

2 6

30 40 50 60 70 80 90 100 200

Flow Rate (GPM)

300 400 500 600 700

030

035

040

045

050

055

060

070

080

090

100

110

120

WGZ

Model

Minimum Flow Nominal Flow Maximum Flow

Inch-Pound S.I. Inch-Pound S.I. Inch-Pound S.I.

GPM Ft. L/S kPa GPM Ft. L/S kPa GPM Ft. L/S kPa

56.9 2.66 3.59 7.96 94.8 7.40 5.98 22.11 158.0 20.55 9.97 61.43

62.8 3.25 3.96 9.71 104.7 9.02 6.61 26.97 174.5 25.07 11.01 74.93

72.2 2.83 4.55 8.45 120.3 7.85 7.59 23.46 200.5 21.80 12.65 65.17

79.6 3.43 5.02 10.26 132.6 9.54 8.37 28.51 221.0 26.49 13.94 79.18

87.5 3.02 5.52 9.02 145.8 8.38 9.20 25.05 243.0 23.28 15.33 69.58

107.3 3.38 6.77 10.11 178.8 9.39 11.28 28.07 298.0 26.09 18.80 77.97

122.4 3.45 7.72 10.31 204.0 9.58 12.87 28.64 340.0 26.62 21.45 79.56

168.7 3.55 10.64 10.62 281.1 9.87 17.73 29.50 468.5 27.41 29.56 81.94

191.2 4.56 12.06 13.64 318.6 12.68 20.10 37.89 531.0 35.21 33.50 105.26

211.0 5.56 13.31 16.61 351.6 15.44 22.18 46.15 586.0 42.89 36.97 128.19


6

Operating Limits

•

•

•

•

Maximum allowable condenser water pressure is 232 psig (1599 kPa).

Maximum allowable cooler water pressure is 363 psig (2509 kPa).

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 3 1

Evaporator

Evaporator and

Condenser

Connections

Circuit 2 Circuit 1

Control Panel

Table 2, Major Components

Unit

Size

System #1 System #2

#3 Comp. #4

Evap.

Vessel

Size

Cond.

Vessel

Size

Expansion Valve

System #1 System #2

030

035

040

045

050

055

060

070

ZR12M3 ZR12M3 ZR16M3 ZR16M3 AC250-102DQ C1010-058 OVE-30-CP100

ZR16M3 ZR16M3 ZR16M3 ZR16M3 AC250-114DQ C1010-070 OVE-30-CP100

ZR16M3 ZR16M3 ZR19M3 ZR19M3 AC250-130DQ C1010-070 Y929-VCP100

ZR19M3 ZR19M3 ZR19M3 ZR19M3 AC250-146DQ C1410-078 Y929-VCP100 Y929-VCP100

ZR250KC C1410-090

080 ZR250KC ZR250KC ZR250KC ZR250KC AC250-194DQ C1410-098 OVE-40-CP100 OVE-40-CP100






Unit Configuration

The chiller unit has two refrigerant circuits, 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.

Figure 4, Schematic Piping Diagram (One of Two Circuits)

P S

Chilled

Water

LWT

Evaporator

P

1

Comp

#1

Comp

#2

S S

F-D

CV

Condenser

S

T

Condenser

Water

Legend:

P

1

LWT

Temperature Sensor

Pressure Transducer

Pressure (High Pressure Cutout)

Temperataure Sensor, Leaving

Chilled Water Control

S

Solenoid Valve

F-D Filter-Drier

CV

Relief Valve

Schrader Fitting

Thermal Expansion Valve

Sight Glass / Moisture Indicator

Charging Valve

Angle Valve

Ball Valve


8

Field Wiring Diagrams

Figure 5, WGZ 030AW – 120AW Field Wiring Diagram

DISCONNECT

(BY OTHERS)

UNIT MAIN

TERMINAL BLOCK

GND LUG

3 PHASE

POWER

SUPPLY

TO COMPRESSOR(S)

FUSED CONTROL

CIRCUIT

TRANSFORMER

FIELD

SUPPLIED

OPTION

120 VAC

N

DISCONNECT

(BY OTHERS)

10A

FUSE

120VAC

CONTROL POWER

(BY OTHERS)

TB1

TB1-20

1

2

11

CHW PUMP RELAY

(BY OTHERS)

14

120 VAC 1.0 AMP MAX

CONTROLLER

CONTROL

CIRCUIT

FUSE

120 VAC

N

120 VAC

J15-N08

CDW PUMP RELAY

(BY OTHERS)

120 VAC 1.0 AMP MAX

TB1-12

N

120 VAC

J16-N09

TOWER FAN #1 COIL

(BY OTHERS)

120 VAC 1.0 AMP MAX

TB1-12

J16-N10

N

120 VAC

FACTORY SUPPLIED ALARM

FIELD WIRED

TOWER FAN #2 COIL

(BY OTHERS)

120 VAC 1.0 AMP MAX

ALARM BELL

OPTION

ALARM BELL

RELAY

10

120VAC

15

TIME

CLOCK

AUTO

ON

OFF

TB2

GND

REMOTE STOP SWITCH

(BY OTHERS)

ICE MODE SWITCH

(BY OTHERS)

MANUAL

AUTO

ON

OFF

MANUAL

40

53

42

55

897

IF REMOTE STOP CONTROL

IS USED, REMOVE LEAD 897

FROM TERM 40 TO 53.

900

IF ICE MODE IS USED

REMOVE LEAD

FROM TERM 42 TO 55.

CHW FLOW SWITCH

--MANDATORY--

(BY OTHERS)

NOR. OPEN PUMP AUX.

CONTACTS (OPTIONAL)

CDW FLOW SWITCH

--MANDATORY--

(BY OTHERS)

4-20 MA FOR

CHW RESET

(BY OTHERS)

4-20 MA FOR

DEMAND LIMIT

(BY OTHERS)

NOR. OPEN PUMP AUX.

CONTACTS (OPTIONAL)

33

43

41

53

38

48

49

38

GND

50

51

GND

CONTROLLER

Rx-/Tx-

J11

Rx+/Tx+

GND

1

2

*

COMMUNICATION

PORT

3

330258901-R4


OM WGZ-2

Figure 6, WGZ 030AA – 120AA Field Wiring Diagram (Remote Condenser)

DISCONNECT

(BY OTHERS)

UNIT MAIN

TERMINAL BLOCK GND LUG

3 PHASE

POWER

SUPPLY

TO COMPRESSOR(S)

FUSED CONTROL

CIRCUIT

TRANSFORMER

FIELD

SUPPLIED

OPTION

N

DISCONNECT

(BY OTHERS)

10A

FUSE

120VAC

CONTROL POWER

(BY OTHERS)

120

VAC

TB1

1

FACTORY SUPPLIED ALARM

FIELD WIRED

ALARM BELL

OPTION

CHW PUMP RELAY

(BY OTHERS)

120 VAC 1.0 AMP MAX

ALARM BELL RELAY

10

2

11

14

TB1-20

CONTROL

CIRCUIT

FUSE

120 VAC

N

120VAC

NOTE:

TIME

CLOCK

OFF

AUTO

ON REMOTE STOP SWITCH

(BY OTHERS)

MANUAL

OFF

AUTO

ON ICE MODE SWITCH

(BY OTHERS)

MANUAL

CHW FLOW SWITCH --MANDATORY--

(BY OTHERS)

4-20 MA FOR

CHW RESET

(BY OTHERS)

4-20 MA FOR

DEMAND LIMIT

(BY OTHERS)

OPTIONAL

NOR. OPEN PUMP AUX.

CONTACTS (OPTIONAL)

15

TB2

40

53

42

55

33

43

GND

897

900

38

48

49

38

50

GND

51

TB3

GND

62

65

LIQUID LINE #1 SOLENOID

24 VAC AMP MAX

63

65

LIQUID LINE #2 SOLENOID

24 VAC AMP MAX

67

70

HOT GAS BYPASS #1 SOLENOID

24 VAC AMP MAX

68

HOT GAS BYPASS #2 SOLENOID

24 VAC AMP MAX

70

CONTROLLER

IF REMOTE STOP CONTROL

IS USED, REMOVE LEAD 897

FROM TERM 40 TO 53.

IF ICE MODE IS USED

REMOVE LEAD

FROM TERM 42 TO 55.

CONTROLLER

J11

Rx-/Tx-

Rx+/Tx+

GND

1

2

* COMMUNICATION

PORT

3

N

N

N

N

24 VAC

24 VAC

24 VAC

24 VAC

120 VAC

FAN MOTOR #1 COIL (BY OTHERS)

120 VAC 1.0 AMP MAX

J15-N08

TB1-12

N

120 VAC

J16-N09

CONDENSER FAN MOTORS

CAN ALSO BE CONTROLLED

BY PRESSURE SWITCHES

ON THE CONDENSER.


120 VAC 1.0 AMP MAX

J16-N010


120 VAC 1.0 AMP MAX

J16-N011


120 VAC 1.0 AMP MAX

J18-N013


120 VAC 1.0 AMP MAX

J22-N016


120 VAC 1.0 AMP MAX

J22-N017

120 VAC

120 VAC

120 VAC

120 VAC

120 VAC

330259001-R4


120 VAC 1.0 AMP MAX

J22-N018


120 VAC 1.0 AMP MAX

120 VAC

WGZ 030A through 120A 9

10

Control Panel Layout

Figure 7, Typical Control Panel

MicroTech II Unit

Controller

Terminal Strips

S1, PS1, PS2

Switches

(4) Compressor

Contactors

(3) 24V Controller

Transformers

110V Control

Transformer

Space for

Optional Circuit

Breakers and

Multi-point

Connection

Grounding Lug

Disconnect

Switch

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.


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, noncorrosive 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 onethird 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.

5. Put the main power and control circuit disconnects to the “on” position.


12

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 onetime 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

1. Close the manual liquid line shutoff valves.

2. After the compressors have pumped down, turn off the water pumps.

3. Turn off all power to the unit.

4. Move the control service switch S1 to the “off” position.

5. Close the discharge shutoff valves on the compressor(s) and the liquid outlet valves at the condenser.

6. Tag all opened disconnect switches to warn against start-up before opening the compressor suction and discharge valves.

7. 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.


OM WGZ-2

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. Open the compressor discharge valves until backseated. 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.

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 Dead Band=3.0°F StartDelta=5.0°F StopDelta=2.0°F

LWT=40.0

°F

Figure 8, Staging/Starting Temperatures

EWT

Evap Delta-T Set 10.0°F

LWT Set

50.0°F

40.0°F

Start Delta T

46.5°F

41.5°F

½ DB

40.0°F

½ DB

38.5°F

Stop Delta T

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

14 WGZ 030A through 120A OM WGZ-2

OM WGZ-2 dead band, 41.5

°F in this case. If the LWT stays above 41.5°F, all of three 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 compressor 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 8, 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 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 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


After Stage Up Delay times out then, LVG Evap


Continued next page.

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


16

Description

Stage #4 OFF

Stage #3 OFF

Stage #2 OFF

Stage #1 OFF

Occurs When:

After Stage Down Delay times out then, LVG

Evap T < Evap LWT SP – (CB/2)


Evap T < Evap LWT SP – (DB/2)


Evap T < Evap LWT SP – (DB/2)


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, Compressor #3 or #4

(depending on circuit) 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 compressor 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 30.

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 44.

Some means of discharge pressure control must be installed if the condenser water temperature can fall below 60

°F (16°C).


Condenser Fan Control

Model AA 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 44.

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.


MicroTech II Controller

Controller Software Version

This manual is based on software version WGZD20102B. The “02B” 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 troublefree 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 watercooled 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 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.


OM WGZ-2

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 9, Keypad and Display in MENU Mode

Key to Screen

P h

Air Conditioning

<

<

<

ALARM

VIEW

SET

Menu Key

Arrow Keys "Enter" Key

The four arrow keys (UP, DOWN, LEFT, RIGHT) have three modes of use.

1. Scroll between data screens as indicated by the arrows (default mode).

2. 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).

3. Change field values in edit mode according to the following table:

UP Increment

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

# Description Type Range

1

2

3

Evaporator Refrigerant Pressure #1

Evaporator Refrigerant Pressure #2

Condenser Refrigerant Pressure #1

C1

C2

C1

0.5 – 4.5 VDC (NOTE 1)

0.5 – 4.5 VDC (NOTE 1)

0.5 – 4.5 VDC (NOTE 1)

0 to 132 psi

0 to 132 psi

3.6 to 410 psi

4

5

6

7

Leaving Evaporator Water Temperature

Condenser Entering or Outside

Ambient Temperature (NOTE 2)

Condenser Refrigerant Pressure #2

Reset of Leaving Water Temperature

UT

UT

C2

UT

Thermister (10k at 77°F,

25°C)

Thermister (10k at 77

°F,

25°C)

0.1 to 0.9 VDC

4-20 mA Current

-58 to 212°F

-58 to 212°F

3.6 to 410 psi

0-(10 to 60°F)

8 Demand Limit

9

10

Compressor Suction Temperature #1

Compressor Suction Temperature #2

UT

C1

C2

4-20 mA Current

Thermister (10k at 77°F,

25°C)

Thermister (10k at 77

°F,

25°C)

0-100 % Load

-58 to 212°F

-58 to 212°F

NOTES:

1. Value at the converter board input. Value at the converter board output is 0.1 VDC – 0.9 VDC.

2. If Water Cooled = Y, then Entering Condenser. If Water Cooled = N, then Outside Ambient.


20

Table 5, Analog Outputs

# Description

1 Cooling Tower Bypass Valve Position

2 Cooling Tower VFD Speed

0 to 10 VDC

0 to 10 VDC

Table 6, Digital Inputs


0 to 100% Open

0 to 100%

1

2

3

Unit OFF Switch

Pump Down Switch #1

Evaporator Water Flow Switch

4 Motor Protection #1

5 Open

6

7

Pump Down Switch #2

Motor Protection #2

8 Open

9 Phase Voltage Fault #1 (See Note 1)

10 Phase Voltage Fault #2 (See Note 1)

11 Ground Fault Prot. #1 (See Note 2)

12 Ground Fault Prot. #2 (See Note 2)

13 Remote Start/Stop

14 Condenser Water Flow Switch

15 Mechanical High Pressure #1

16 Mechanical High Pressure #2

17 Ice Mode Switch

18 Open

UT

C1

UT

0 VAC (Stop)

0 VAC (Stop)

0 VAC (No Flow)

C1 0 VAC (Fault)

C2

C2

0 VAC (Stop)

0 VAC (Fault)

C1

C2

C1

C2

UT

UT

C2

C2

0 VAC (Fault)

0 VAC (Fault)

0 VAC (Fault)

0 VAC (Fault)

0 VAC (Stop)

0 VAC (No Flow)

0 VAC (High

Pressure/Off)

0 VAC (High

Pressure/Off)

UT 0 VAC (Normal)

24 VAC (Auto)

24 VAC (Start)

24 VAC (Flow)

24 VAC (No Fault)

24 VAC (Start)

24 VAC (No Fault)

24 VAC (No Fault)

24 VAC (No Fault)

24 VAC (No Fault)

24 VAC (No Fault)

24 VAC (Start)

24 VAC (Flow)

24 VAC (OK )

24 VAC (OK )

24 VAC (Ice)

Note 1: See Equipment Protection 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 Equipment Protection 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


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


Condenser Fan #3– Water Cooled

6

=N /Tower Fan #2-Water Cooled=Y

7 Liquid Line #1

Condenser Fan #2 – Water Cooled

8

=N /Tower Fan #1-Water Cooled=Y



11 Condenser Fan #4

12 Liquid Line #2

13 Condenser Fan #5

14 Hot Gas Bypass #1

15 Hot Gas Bypass #2

16 Condenser Fan #6

17 Condenser Fan #7

18 Condenser Fan #8

C1,C2,

UT

UT

C1 /

UT

C1

C1

C1 /

UT

C1

C2 /

UT

C2

C2

C2

C2

C1

C1

C2

C2

C1

C2

Output ON

Alarm Indicator Alarm OFF

Pump Contactor Pump OFF

Fan Contactor/

Pump Contactor

Fan OFF

Starter

Starter

Fan Contactor

Alarm ON

Pump ON

Fan ON

Compressor OFF Compressor ON


Fan OFF Fan ON

Solenoid

Fan Contactor

Starter

Starter

Fan Contactor

Solenoid

Fan Contactor

Solenoid

Solenoid

Fan Contactor

Fan Contactor

Fan Contactor

Cooling OFF

Fan OFF

Cooling ON

Fan ON



Fan OFF

Cooling OFF

Fan OFF

Fan ON

Cooling ON

Fan ON

Cooling OFF

Cooling OFF

Fan OFF

Fan OFF

Fan OFF

Cooling ON

Cooling ON

Fan ON

Fan ON

Fan ON


OM WGZ-2

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

Unit Enable

Unit Mode

Control source

Available Modes

XXX Display Units

BAS Protocol

Ident Number

Baud Rate

Evap LWT (COOL & GLYCOL)

Ice LWT (ICE)

Evap Delta T

Startup Delta T

Stop Delta T

Max Pulldown Rate

Low Ambient Lockout (Water-cooled = No)

Demand Limit

* Water Cooled

* Refrigerant Select

* Phase Voltage Protection

* Ground Fault Protection

* Set at Factory

Speedtrol Option

Staging

Stage Up Delay

Stage Down Delay

Timers

Evap Recirculate Timer

Cond Pump Recirculate Timer (Water-cool)

Low Evap Pressure Delay

LowOATTmr

Ice Time Delay

Clear Ice Timer

Hot Gas Bypass Solenoid Valve Delay

Start-Start

Stop-Start

Alarms

Evaporator Freeze

Condenser Freeze

Low Evap Pressure

Evap Flow Proof

High Condenser Pressure

Events

Low Evap Pressure-Hold R22

Low Evap Pressure-Hold R407c

Low Evap Pressure-Unload R22

Low Evap Pressure-Unload R407c

High Condenser Stage Down

Condenser Fans (Water Cooled = N)

Fans Per Circuit

Speedtrol; Option

C1/ C2 – Stage #1 / #2 On (OAT < 70

°F)

C1/ C2 – Stage #3 / #4 On

Continued next page

OFF

COOL

OFF, ON

COOL, COOL w/Glycol, ICE w/Glycol

DIGITAL INPUT KEYPAD, BAS, DIGITAL INPUT

COOL

°F/psi

COOL, COOL w/Glycol, /ICE w/Glycol

°F/psi, °C/kPa

NONE NONE, BACnet, LonWorks, Modbus

001 001-999

9600 1200, 2400, 4800, 9600, 19200

44. 0

°F

40. 0

°F

10. 0

20.0 to 60.0

°F

20.0 to 40.0

°F

°F 6.0

2.0

°F 1.0

0.5

°F

1.0

°F 0.5

35.0

°F

0 to 3.0

°F

5.0

°F

°F

-2(35) to 70

°F

Off Off, On

N

None

N

N

N

N,Y

R22, R407c

N,Y

N,Y

N,Y

240

30

90 to 480 sec

20 to 60 sec

30 sec

30 sec

30 sec

60 sec

12 hrs

No

30 sec

15 min

5 min

36.0

°F

34.0 °F

58 psi

3 sec

380 psi

59 psi

52 psi

58 psi

50 psi

370 psi

2

N

200 psi

290 psi

15 to 300 sec

15 to 90 sec

15 sec to 30sec

30 to 240 sec

1-23 Hrs

No, Yes

30 to 180 sec

10 to 60 min

3 to 20 min

18 to 42

°F

18 to 42 °F

30 to 60 psi

1 to 10 sec

380 to 390 psi

24 to 65 psi

20 to 65 psi

24 to 65 psi

20 to 65 psi

365 to 375 psi

2 to 4

N, Y

140 to 200 psi

220 to 330 psi

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

O

O

O

O

M

M

M

O

M

M

M

M

--

M

M

M

M

M

O

O

O

M

O


22

C1/ C2 – Stage #5 / #6 On

C1/ C2 – Stage #7/ #8 On

C1/ C2 – Stage #3/ #4 Off



Cooling Tower (Water Cooled = Y)

Tower Control

Tower Stages

Stage Up Time

Stage Down Time

Stage Differential

Stage #1 On

Stage #2 On

Description Default Range PW

Cooling Tower (Water Cooled = Y)

Valve / VFD

300 psi

310 psi

180 psi

190 psi

200 psi

None

2

2 min

5 min

3.0

°F

70 °F

75

°F

220 to 330 psi

220 to 330 psi

150 to 220 psi

150 to 220 psi

150 to 220 psi

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

M

M

M

M

M

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

None, Valve Setpoint, 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%

Normally Closed (NC), Normally Open

(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

M

M

M

M

M

M

M

Protection (Shutdown) Alarms

Equipment protection alarms trigger a rapid compressor shutdown. The following table identifies each equipment protection alarm, gives the condition that causes the alarm to occur, and states the action taken because of the alarm. Most equipment protection alarms require a manual reset. These alarms will energize a remote alarm if the unit is so wired in the field.

Table 9, Equipment Protection Alarms

NOTE: SP = Setpoint

NOTE : UT = Rapid Stop for the entire unit (Both Circuits), CT = Rapid Stop for that circuit only

No Evaporator Water

Flow

No Condenser Water

Flow

Low Evaporator

Pressure

High Condenser

Pressure

Mechanical High

Pressure

Motor Protection

Phase Voltage

Protection (optional)

Ground Fault

Protection (optional)

Action

When:

Taken

Evap Pump State = RUN AND

Evap Flow Digital Input = No Flow & High Condenser

Pressure for > Evap Flow Proof SP]

Cond Flow Digital Input = No Flow for > Evap Flow Proof]

Note: Water Cooled = Y Only

Rapid

Stop UT

Rapid

Stop UT

Evaporator Press < Low Evap Pressure SP start Low Evap

Pressure Time Delay – if after Time Delay if Evap Press >

SP continue else stop

Condenser Press & Condenser Flow > High Condenser

Pressure SP

For C1, Motor Start #1 On & Digital Input = High Pressure

For C2, Motor Start #2 On & Digital Input = High Pressure

Digital Input = High Motor Temperature

On Power Up – Delay 150 Sec. Before checking

If Phase Voltage Protection = Y, Then

Digital Input = Phase/Voltage Problem

If Ground Fault Protection = Y, Then

Digital Input = Ground Fault Protection Problem

Rapid

Stop CT

Rapid

Stop CT

Rapid

Stop CT

Rapid

Stop CT

Rapid

Stop CT

Rapid

Stop CT

Reset

Manual

Manual

Manual

Manual

Manual

Manual

Manual

Continued on next page.


OM WGZ-2

Re-Start Fault

Evap. Freeze Protect

Leaving Evap. Water

Temp. Sensor Fault

Evaporator Pressure

Sensor Fault

Condenser Pressure

Sensor Fault

Condenser Entering or Outside Ambient

Temp. Sensor Fault

Re-Start = Third Time

Evap LWT < Evaporator Freeze SP

Sensor shorted or open



Sensor is open or shorted

Action

When:

Taken

Rapid

Stop UT

Rapid

Stop CT

Rapid

Stop UT

Rapid

Stop CT

Rapid

Stop CT

Rapid

Stop UT

Reset

Manual

Manual

Manual

Manual

Manual

Manual

Event (Limit) Alarms

The following alarms do not cause a rapid shutdown but limit operation of the chiller in some way as described in the Action Taken column. These alarms do not trigger a remote alarm signal. They do appear in the Active Alarm menu, are logged, and light the Alarm

LED. A password must be active to view these events in the Event Log.

Table 10, Limit Alarms

NOTE: SP = Setpoint

NOTE: UT = Rapid Stop for the entire unit (Both Circuits), CT = Rapid Stop for that circuit only

Description Occurs When: Action Taken

Condenser Pressure

High – Unload

Low Ambient

Lockout

Evaporator Pressure

Low – Hold

Evaporator Pressure

Low – Unload

Pressure > High Condenser

Stage Down setpoint

Outside Ambient < Low

Ambient Lockout SP

Note: Water Cooled = N Only

Pressure < Low Evap

Pressure–Hold setpoint

Pressure < Low Evap

Pressure–Unload setpoint

Stage off lag compressor on the circuit

Stage down & Shutoff

Inhibit staging on lag compressor on the circuit

Stage off lag compressor on the circuit

Reset

Condenser Press drops below

(SP – 100psi)

Outside Ambient >

Low Amb Lockout

(SP + 5ºF)

Evap Press rises above (SP + 8psi)

Evap Press rises above (SP + 10 psi

+ Stage Up Delta T)

Condenser Freeze

Protect

Cond Sat Refr Temp <

Condenser Freeze SP AND

Cond Pump State = OFF

Note: Water Cooled = Y Only

Start condenser pump

Cond Sat Refr Temp

> (Condenser

Freeze SP + 2°F)

Note, See Table 11 for low pressure hold and unload setpoints.

CT

UT

CT

CT

UT

Table 11,Refrigerant Sensitive Set Point Defaults and Adjustment Range

Set Point Name

Low Evaporator

Pressure Hold Loading

Low Evaporator

Pressure Unload

Default

(psi)

R22 Refrigerant

Adjustment Range

(psi)

59.0

58.0

24.0 – 65.0 (with glycol)

55.0 – 65.0 (w/o glycol)


55.0 – 65.0 (w/o glycol)

Default

(psi)

R407c Refrigerant

Adjustment Range

(psi)

52.0

50.0


58.0 – 75.0 (w/o glycol)


58.0 – 75.0 (w/o glycol)

Unit Enable

•

Enabling and disabling the chiller is controlled by the Unit Enable Setpoint with options of OFF and ON. This setpoint can be altered by the keypad, BAS, Unit OFF input, and Remote input. The Control Source Setpoint determines which sources can change the Unit Enable Setpoint with options of SWITCHES, KEYPAD or

NETWORK.

Changing the Unit Enable Setpoint can be accomplished according to the following table.


24

Table 12, Unit Enable Combinations

NOTE: An “x” indicates that the value is ignored.

Unit Off

Input

Control Source

Setpoint

Remote

Input

Keypad

Entry

BAS

Request

Unit

Enable x SWITCHES 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 Selection

The overall operating mode of the chiller is set by the Unit Mode Setpoint with options of

COOL, COOL w/Glycol, ICE w/Glycol, and TEST. This setpoint can be altered by the keypad, BAS, and Mode input. Changes to the Unit Mode Setpoint are controlled by two additional setpoints.

Available Modes Setpoint: Determines the operational modes available at any time with options of COOL, COOL w/Glycol, COOL/ICE w/Glycol, and TEST.

Control Source Setpoint: Determines the source that can change the Unit Mode Setpoint with options of KEYPAD, NETWORK, or SWITCHES.

Table 13, Unit Mode Combinations

Changing the Unit Mode Setpoint can be accomplished according to the following table.

NOTE: An “x” indicates that the value is ignored.

Control

Source

Setpoint

Mode

Input

Keypad Entry

BAS

Request

Available Modes

Setpoint

Unit Mode x x x x COOL COOL x

SWITCHES x

OFF x x x x

COOL w/Glycol

COOL/ICE w/Glycol

COOL w/Glycol

COOL w/Glycol

SWITCHES ON

KEYPAD x x

COOL w/Glycol x COOL/ICE w/Glycol COOL w/Glycol

ICE w/Glycol

NETWORK

NETWORK x x x x

COOL

ICE

COOL/ICE w/Glycol

COOL/ICE w/Glycol

COOL w/Glycol

ICE w/Glycol x x x x TEST TEST

Low Ambient Start (Remote Condenser Only)

If Water Cooled = Y, then this function is not applicable.

If SpeedTrol = N, this step is bypassed and unit starts in the normal operation. If the

SpeedTrol = Y then unit starts per table below. This step will bypass the “Low Evaporator

Pressure” alarm until Low Ambient Start is completed.

When there is a call for Cooling the following steps are used.


OM WGZ-2

Table 14, Low Ambient Start Sequence

NOTE: CT = Rapid Stop for that circuit only

Descriptio n

Occurs When:

Check #1

Check #2

Check #3

Check #4

Action Taken

After 15 Seconds after starting first

Rapid Stop – See compressor, If the Evap Press is < 0.48 times

Low Ambient Rethe Low Evap Pressure SP take action, else continue

Start below

After 15 Seconds after Check #1, If the Evap Rapid Stop – See

Press is < 0.66 times the Low Evap Pressure

SP take action, else continue (30 Sec Total)

After 15 Seconds after Check #2, If the Evap

Press is < 0.83 times the Low Evap Pressure

SP take action, else continue (45 Sec Total)

Low Ambient Re-

Start below

Rapid Stop – See

Low Ambient Re-

Start below

After 15 Seconds after Check #3, If the Evap

Press is < Low Evap Pressure SP take action, else continue in normal operation (60 Sec

Total)

Rapid Stop – See

Low Ambient Re-

Start below

CT

CT

CT

CT

Low Ambient Re-Start

If the Evap Pressure fails during the low ambient start, the controller waits until the anticycle timers expire then tries to re-start. It will attempt a start 3 times, and reset the counter if unit continues in normal operation. If it fails on the third attempt, it will initiate the Low

Ambient Re-Start Alarm Fault (Manual Reset).

Automatic Adjusted Limits

The following are setpoints that will be changed are based on the option selected.

Evaporator Leaving Water Temperature

Mode Range

Unit Mode = Cool 40 to 60

°F

Unit Mode = Glycol, Ice 20 to 60

°F

Evaporator Freeze Temperature

Mode Range

Unit Mode = Cool 36 to 42

°F

Unit Mode = Glycol, Ice 18 to 42

°F

Low Evaporator Pressure

Mode Range

Unit Mode = Cool 55 to 65 Psig

Unit Mode = Glycol, Ice 30 to 65 Psig

Low Evaporator Pressure Hold and Unload

Mode Range

Unit Mode = Cool 55 to 65 Psig

Unit Mode = Glycol, Ice 31 to 65 Psig

Low Ambient Lockout Temperature

SpeedTrol Range

SpeedTrol = N

SpeedTrol = Y

35 – 60

°F

-2 – 60

°F


26

Staging Parameters

Lockouts

There are conditions that shall prevent a start when the unit status is AUTO.

Low Ambient Lockout

If the unit status is AUTO, but no compressors have started, and the outside ambient temperature drops below the low ambient lockout setpoint, the unit will transition to the

Low Ambient Lockout state. This condition will not trigger an alarm. The condition will be indicated by showing the unit status as “Low Amb Lockout”. The chilled water pump will shut off. If lockout occurs while the unit is running, the compressors will pump down.

Compressor start will be delayed until the outside ambient temperature rises to the setpoint plus 5 degrees F.

Wait For Evap or Cond Water Flow

If the unit status is AUTO and the evap pump status is START, then the unit will wait for the evaporator and condenser flow switches to close. During this time, the condition will be indicated by showing the unit status as “Wait For Flow”. The water flow loss logic will allow the Loss of Flow alarms to be automatically reset two times in any 24 hour period.

• If either water flow is lost any time a compressor is running the chiller will shutdown all of the running compressors and each Cirucit’s status will become Off:Ready.

• The Unit status will become Auto:Wait For Flow and the Evaporator or

CondenserWater Pump status will change to Start. The Unit’s alarm output will be turned On and the red LED behind the upper left key of the control will turn On.

• When the flow returns without interruption for the Evaporator Flow Recirculation Time

(30 seconds is the default time) the unit is allowed to start as the cycle and staging timers are cleared.

• The alarm output and red LED will be turned off and normal start and staging logic is allowed to proceed.

• If water flow is lost a second time with in 24 hours the procedure described above is repeated.

• A third occurrence of evaporator flow loss in 24 hours triggers the standard Evaporator or Condenser Water Flow Loss alarm. All circuits with running compressors shutdown and the Unit status becomes Off:Alarm.

• The standard Evaporator or Condenser Water Flow Loss alarm must be manually cleared before the unit is allowed to restart.

• The twenty four hour timer that limits the auto restarts is reset when the control’s clock rolls over to 00:00 each night

Capacity Overrides

The following conditions override the capacity control mode when the chiller is in the cool or ice mode. The purpose of the overrides is to keep the unit online (although at reduced capacity) during certain abnormal operating condition. If and when the “off” condition returns to normal, the override is eliminated and the unit returns to normal operation based on the capacity control.

Low Evaporator Pressure

If the evaporator pressure drops below the Low Evaporator Pressure Hold setpoint and only one compressor on that circuit is running, the second compressor is prevented from starting.

If the evaporator pressure drops below the Low Evaporator Pressure Unload setpoint, and both compressors on the circuit are running, the “first off” compressor on that circuit is shut off.


OM WGZ-2

Maximum LWT Rate

The maximum rate at which the leaving water temperature can drop is limited at all times by the Maximum Rate setpoint (2

°F/minute). If the rate exceeds this setpoint, no more compressors will be started until the pulldown rate is less than 2

°F/minute.

High Condenser Pressure

If the discharge pressure rises above the High Condenser Pressure Unload setpoint, and both compressors on the circuit are running, the “first off” compressor on the circuit is shut off.

Digital Output Control

Each digital output is be controlled according to the following rules. All outputs are initialized to OFF at power on.

Alarm – (Terminals J12 – NO1)

This output is turned ON when any Equipment Protection ALARM occurs. It is turned

OFF when all alarms have been cleared.

Evaporator Pump – (Terminals J12 – NO2)

An Evaporator Water Pump output is ON if the Evap State is set to START or RUN.

Hot Gas Bypass Solenoid – (Terminals J21 – NO14, J21 – NO15)

This output shall be ON when the Lead Compressor per Circuit is the only compressor ON, except during Pumpdown.

This output shall be ON when the Compressors are ON. It shall be OFF for all other cases.

Digital Output Control

Each digital output is controlled according to the following rules. All outputs are initialized to OFF at power on.

Fan #1 to #8 (Air-Cooled Condensers)

[Water Cooled = N] – Condenser Fans Staging is based on condenser pressure as selected by Fan Stage On & Off setpoints. Fans 1, 3, 5 and 7 are for circuit 1, and fans 2, 4, 6, and 8 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 pressure gets up to the stage on setpoint.

Condenser Pump and Tower Fans (Water-Cooled Condenser)

[Water Cooled = Y] – Condenser Pump is 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

• Stage up and stage down timer values

• 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 starts. The first stage turns 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 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 occur when the following conditions are met:

• The stage-down timer completes

• The ECWT is < Stage #X ON (Temp) setpoint – Stage Differential (Temp) setpoint

• 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 restarts both the stage-up and-stage down timers. Only one fan output is switched at a time (except that all outputs switch OFF when the condenser pump state equals OFF).

Analog Output Control

Each analog output is controlled according to the following rules/algorithms and in accordance with whether the Compressor Mode setpoint is set to AUTO or MANUAL

(normal operation). All outputs shall be initialized to 0 at power on.

Cooling Tower Bypass Valve

When the Valve/VFD Control setpoint is set to None or VFD Stage, this output is set to 0.

Otherwise, it is controlled as described below.

Initial Valve Position

When the condenser pump is not in the RUN state, the valve output is set as a function of entering condenser water temperature (ECWT) per the following graph.


OM WGZ-2

Max Position @

Setpoint

(90°F)

Initial Valve Position

(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 is controlled in one of two modes as specified by the Valve/VFD Control setpoint. The controlled parameter is 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)

• 10 to 0 VDC (Valve Type = NO)

Valve Setpoint Mode

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 proportional-derivative

(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 is computed once every 5 seconds according to the following equation.

• 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 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 Active Setpoint

1

2

3

4

Stage #1 ON

Stage #2 ON

Stage #3 ON

Stage #4 ON


30

Cooling Tower Fan VFD

When the Valve/VFD Control setpoint is set to None, Valve Setpoint, or Valve Stage, this output is set to 0. Otherwise, it is controlled in a manner identical to Valve Stage Mode

(above) except that (1) it is 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

Evaporator Water Pump State Control

Operation of the evaporator pump is controlled by the state-transition diagram shown below. A state variable (Evap State) is used to maintain the current state (OFF, START, or

RUN). The fixed 30 second timer will start when flow is first indicated by the Evaporator

Water Flow Switch digital input. This timer is considered expired after 30 seconds.

Power ON

TEST: Unit alarm (except evap freeze) OR

Circuit alarm on both circuits OR

Unit enable = off OR

Circuit PumpDn Switch = off for all circuits (and pumpdn completed)

RUN

OFF

TEST: Unit Enable = On

AND at least one circuit is enabled and not in alarm state OR

Evap Freeze Protection

TEST: Flow OK for

30 Seconds

TEST: Unit alarm (except evap freeze) OR

Circuit alarm on both circuits OR

Unit enable = off OR

Circuit PumpDn Switch = off for all circuits (and pumpdn completed)

START

Condenser Water Pump State Control

Operation of the Condenser pump is controlled by the state-transition diagram shown below. A state variable (Cond State) is used to maintain the current state (OFF, START, or

RUN).

Condenser Pump State Diagram

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

Off

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

Unit State=Auto AND

Any Circuit Available AND

Stage up now = True]

OR

Cond Refrig Freeze Event

AND No Cond Flow Alarm

[Cond Pump State = Start

AND Flow Switch Closed] for time > Cond Pmp

Recirc Time seconds

Start


OM WGZ-2

Condenser Pump Control

The Condenser Flow Recirculation Time Set Point is found on the Unit Set Points Screen

Five, line four. The default value is 30 seconds and the set point is adjustable from 15 seconds to 90 seconds.

The condenser water pump starts if the control has detected sufficient load after the evaporator water pump has started and evaporator water flow has been established.

The condenser water pump is enabled in the “Start” mode. It will remain in the “Start” mode until condenser water flow has been established. If continuous flow has been established for Condenser Flow Recirculation Time the condenser water pump mode becomes “Run” and the first compressor is enabled.

If no flow is detected while the condenser water pump is in the “Start” mode, the logic described on page 26 will be in effect

Inconsistent condenser water flow will hold the condenser water pump in the “Start” mode until constant flow has been established for Condenser Flow Recirculation Time seconds.

When the condenser water pump is in “Run” mode, if condenser water loop flow is lost for three seconds a “No Condenser Water Flow” alarm is generated.

The condenser water pump mode is displayed on the Unit Status Screen One, line four. It is combined with the evaporator pump mode and the line states “Ev/Cnd Pmp Off/Off” when both pumps are off. The text before the second ‘/’ is the evaporator water pump mode and the text after the second ‘/’ is the condenser water pump mode.

The condenser water pump mode and the Condenser Flow Recirculation Time set point are not displayed when the unit is configured for a remote condenser (Water Cooled =Off).

The condenser water pump logic will shutdown the condenser water pump when the evaporator pump state has been changed to Start. When the evaporator pump is in the

Start state the Unit is waiting for evaporator water flow to be confirmed and no compressors will start. It is not necessary to run the condenser pump while waiting for evaporator flow to be confirmed.

Using the Controller

Getting Started

There are two basic procedures to learn in order to utilize the MicroTech II controller:

1. Navigating through the menu matrix to reach a desired menu screen and knowing where a particular screen is located.

2. 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.

D. .

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 11. (A detailed description of each menu begins on page 34.) 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 9. This corresponds to the second row of screens on Figure 11. One of these groups of screens can then be selected by pressing the key connected to it via the pathway shown in Figure 9 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.

MENU Key

The MENU key is used to switch between the shortcut method (known as the MENU mode and as shown in Figure 9) 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.


OM WGZ-2

Figure 10, 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

ENTER Key

Pressing the ENTER key changes the function of the ARROW keys to the editing function as shown below: setting.

UP Increment, increases the value of the 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. Press MENU key to go to the MENU mode.

2. Press SET (the UP Key) to go to the setpoint menus.

3. Press UNIT SPs (the Right key) to go to setpoints associated with unit operation.

4. 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.

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.


34

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 11. A description of each menu begins on page

34.

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 11, Menu Matrix

“MENU”

“VIEW” MENUS

UNIT CIRCUITS REFRIGERANT FANS

VIEW UNIT VIEW UNIT

STATUS

(1)

TEMP

(1)

VIEW

CIRC #1

STATUS

(1)

VIEW

REFRIGERANT

CIRCUIT #1

(1)

VIEW UNIT VIEW UNIT

STATUS

(5)

TEMP

(2)

VIEW

COMP #1

STATUS

VIEW

CIRC #2

STATUS

VIEW EVAP

(2)

(3) (3)

⇐ Continued ⇐

(Right side of matrix continued from above)m

“ALARM” MENUS

VIEW

CIRC #2

STATUS

(1)

VIEW

REFRIGERANT

VIEW FAN/TOWER

(1)

CIRCUIT #2

(1)

VIEW EVAP

(2)

VIEW FAN/TOWER

(n)

“SET” MENUS

ALARM LOG

(LAST)

TYPE, TIME

ALARM LOG

(SECOND TO

LAST)

ACTIVE ALARM (1)

TYPE, TIME

ACTIVE ALARM (3)

CLEAR/VIEW

SET UNIT SPs, (1) SET COMP SPs SET LIMIT ALARMS SET FANS (1)

(1) (1) STAGES

FANTROL

SET

TOWER (1)

ALARM LOG

(NEXT TO LAST)

ACTIVE ALARM (2)

TYPE, TIME

ADDITIONAL

SET UNIT SPs, (2) SET COMP SPs

(2)

SET LIMIT ALARMS

(2)

SET FANS (2)

STAGE ON

SET

TOWER (2)

SET UNIT SPs, (3) SET LIMIT ALARMS SET FANS (3)

(3) STAGE OFF

SET

TOWER (3)

ALARM LOG

LAST 25 SHOWN

SET UNIT SPs, (4)

(to 13)

SET TOWER

(to n)

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.

Menu Descriptions

This section contains information on each screen. The menu screens are in order of the matrix in Figure 11 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.


OM WGZ-2

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 <

UNIT <

TEMP

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.


Demand Limit=Stg 4

Network Limit=Stg 4


36


Stg Up Delay=XXX sec

Stg Dn Delay=XXX sec

Ice Delay=XXh XXm


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 Table 7 on page 20 for number reference.


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 Tempertures

Water Cooled = Y

VIEW UNIT TEMP (1)

Evap LWT = XX.X

°F

Cond EWT = XXX.X

°F

LWT Target = XX.X

°F

Water Cooled = N


Evap LWT = XX.X

°F

OAT = XXX.X

°F

LWT Target = XX.X

°F

The difference between the two screens above is that water-cooled 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.


LWT Pulldn= XX.X

°F

Control Band= XX.X

°F


Control Temps

Start Up XX.X

°F

Stage Up XX.X

°F


Control Temps

Start Down XX.X

°F

Stage Down XX.X

°F


OM WGZ-2

View Circuit

VIEW CIRCUIT#1 (1)

OFF


Comp 1 = OFF

Hours = XXXXX

Starts = XXXXX

VIEW CIRCUITt#1 (3)

Comp 3 = OFF

Hours = XXXXX

Starts = XXXXX


Off


Comp 2 = OFF

Hours = XXXXX

Starts = XXXXX


Comp 4 = OFF

Hours = XXXXX

Starts = XXXXX

View Refrigerant

VIEW REFRG Cir 1 (1)

Evap Press XXX.X psi

Cond Press XXX.X psi


Sat Evap XXX.X

°F

Sat Cond XXX.X

°F i

WGZ 030A through 120A


Evap Dew XXX.X

°F

Cond Mid XXX.X

°F

37

38

Code has been created that converts R407c refrigerant pressures to saturated temperatures.

R407c refrigerant is a blended refrigerant. To overcome the glide factor, the saturated temperatures are displayed as dew point temperatures for pressures below 120.0 psi.

Saturated temperatures for refrigerant pressures greater than 120.0 psi are displayed as midpoint temperatures (a mid-point temperature is the average of the dew-point and bubblepoint temperatures for any pressure). As a result, the View Refrigerant Screen Two for each circuit shows “Evap Dew” temperature on line two and “Cond Mid” on line three when

R407c refrigerant is selected.

Modified macroblocks convert R22 refrigerant pressure to saturated temperatures with the same resolution and accuracy as the R407c conversions. The control does not use saturated temperature for control purposes, but they are displayed on the control screen. Line two of the View Refrigerant Screen Two for each circuit still says “Sat Evap” and line three says

“Sat Cond” when R22 refrigerant is selected.


SuctionTemp=XXX.X

°F

Surperheat = XXX.X

°F

EvapApproach= XX.X

°F


Evap Press XXX.X psi

Cond Press XXX.X psi


Sat Evap XXX.X

°F

Sat Cond XXX.X

°F i


Evap Dew XXX.X

°F

Cond Mid XXX.X

°F


SuctionTemp=XXX.X

°F

Surperheat = XXX.X

°F

EvapApproach= XX.X

°F

Water Cooled = Y Only

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

VIEW TOWER (2)


OM WGZ-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

Circuit#1 ON = 1 of 4

Circuit#2 ON = 1 of 4

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.

Screen Definitions – ALARM

ALARM ACTIVE (X)

Alarm Description hh:mm:ss dd/mmm/yyyy

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 (1)

Alarm Description hh:mm:ss dd/mmm/yyyy

Data

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 – 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.


40

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 4 th

line and can be:

1. 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.

2. SWITCHES, in which an external switch is wired across terminals #25 and #35. (See wiring diagram page 8 or 9.)

3. NETWORK, used with BAS signal, which is wired to the three communication ports.

Unit Mode settings can be

1. COOL, normal setting used with chilled water air-condition applications.

2. COOL w/GLYCOL, used with low temperature, glycol applications. It allows a lower

LWT setpoint to be used.

3. 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 three-position 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

Available Modes

(2)

=COOL

Set w/Unit Switch Off


Evap LWT = XX.X

°F

Ice LWT = XX.X

°F

EvapDeltaT= XX.X

°F


Start Delta= XX.X

°F

Stop Delta= XX.X

°F

See page 14 for an explanation of compressor staging.


Max Pulldn=x.x

°F/min

Evap Recirc=XXX sec

LowAmbLock=XX.X

°F


Max Pulldn=x.x

°F/min

Evap Recirc=XXX sec

Cond Recirc=XXX sec


OM WGZ-2

SET UNIT SPs

Demand Limit=Off

(6)

Water cooled=Off

Water Cooled = On is the setting for units with on-board water-cooled condensers.

WaterCooled = OFF is used for units with remote condensers, usually air-cooled.


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 valveclosed when the first compressor on a circuit starts. This delay allows sufficient condenser pressure to build up.

SET UNIT SPs

CLOCK dd/mmm/yyyy hh:mm:ss

(8)

Ini t i a l Scr e e n

SET UNIT SPs

Units =

°F/psi

Lang = ENGLISH

Refrig = None

(9)

• Logic allows the user to change the Refrigerant Type when the manager level password is active. After loading the software initially, the setting is still accessible without entering a password because the setting defaults to none and a Refrigerant Type must be selected before the program can start running.

• The refrigerant select field will display “SELECT TYPE” when no refrigerant type has yet been selected.

• The software has also been changed to prevent the Unit running until a refrigerant type has been selected. Unit will be disabled even if the Unit and Circuit switches are in the

ON position.

SET UNIT SPs

Protocol = NONE

Ident Number=001

Baud Rate=9600

(10)

BAS interface settings, available mid-2003.


Evap Press Sensor

Cir 1 Cir 2 Offset

00.0

00.0

(psi)

The pressure offsets on menus 8 and 9 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


42 negative offset value is then entered to make the controller reading agree with the measured value.


Cond Press Sensor


00.0

00.0

(psi)


Leaving Evaporator

Water Temp Sensor

Offset= 00.0

o

F


OAT/Cond Lvg Water

Temperature Sensor

Offset= 00.0

o

F


Suction Temp Sensor


00.0

00.0

(

o

F)


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 key-press.

Set Compressor Setpoints

SET COMP SPs k,(1)

Clear Cycle Tmr=No

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. Clear Cycle Tmr overrides the anti-recycle timers and should only be used for service testing and not for normal unit operation.

SET COMP SPs (2)

InterStgUp =XXXsec


OM WGZ-2

InterStgDown= XXsec

InterStageUp is the time delay since the last stage change before a compressor can stage on, default is 120 sec.

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.


Comp 1 = Enable

Comp 3 = Enable


Comp 2 = Enable

Comp 4 = Enable

Enable screens #3 and #4 require the manager password to change.

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.


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 low-pressure trips. The default setting is 30 seconds.


GroundFault = N

PhaseVoltage = N

Low OATStartTMR=XXsec


44

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.


Evap Freeze = XX.X

°F

EvapFlowProff=XXXsec

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.

Set Air-Cooled Condenser Fans

Water-cooled = No

SET FANS SPs (1)

Fan Stages=X

Speedtrol=Yes/No


Stage ON psi

#1/2 #3/4 #5/6 #7/8

XXXX XXXX XXXX XXXX


Stage Off psi

#3/4 #5/6 #7/8

XXXX XXXX XXXX

The SET FANS SP screens 2 through 5 establish the discharge pressures that will stage the condenser fans on and off. These screens apply only to units set up for use with air-cooled 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.

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

• 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).


46

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.


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.


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.


Valve/VFD Control=

ValveSP/VFDStage

Valve Type = NC

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 Active Setpoint

1

2

3

4

Stage #1 ON

Stage #2 ON

Stage #3 ON

Stage #4 ON

• 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.


48

Figure 12, Initial Valve Position

Initial Valve Position

(values are examples only)

Max Position @

Setpoint

(90°F)

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)


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.


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.


Valve Control Range

Min = XXX%

Max = XXX%

Defaults are 10% minimum and 90% maximum.


PD Control Loop

Error Gain = XX

Slope Gain = XX

Defaults are 25 for both error and slope.


OM WGZ-2

TEST

TEST UNIT (1)

Alarm Signal – Off

Evap Water Pump=Off

Cond Water Pump=Off

TEST UNIT (2)

Liq Line Sol #1= Off

Compressor #1=Off


TEST UNIT (3)

Liq Line Sol #2= Off



TEST UNIT (4)

Hot Gas Sol #1-Off

Hot Gas Sol #2-Off

TEST UNIT

Fan Motor #1=Off

(5)



TEST UNIT


(6)



TEST UNIT


(7)


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.


50

During edit mode, the display shall show a two-character wide menu pane on the right as shown below.

SET UNIT SPs (X) <D

(data)

(data)

(data)

<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.

BAS Interface

The MicroTech II controller is equipped with the Protocol Selectability

™ feature, an exclusive McQuay feature that provides easy unit interface with a building automation system. If the unit will be tied into a BAS, the controller should have been purchased with the correct factory-installed interface module. The modules can also be added in the field during or after installation.

If an interface module was ordered, one of the following BAS interface installation manuals was shipped with the unit. Contact your local McQuay sales office for a replacement, if necessary.

• IM 735, L

ON W ORKS

® Communication Module Installation

• IM 736, BACnet® Communication Module Installation

• IM 743, Modbus® Communication Module Installation


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.


52

Troubleshooting Chart

PROBLEM POSSIBLE CAUSES

1. Main switch, circuit breakers open.

POSSIBLE CORRECTIVE STEPS

Compressor Will

Not Run

Compressor

Noisy or Vibrating

High Discharge

Pressure

Low Discharge

Pressure

High Suction

Pressure

3. Thermal overloads tripped or fuses blown.

4. Defective contactor or coil.

5. System shut down by equipment protection devices.

7.

1.

2. Improper piping support on suction or

1. Condenser water insufficient or temperature too high.

2. Fouled condenser tubes (water-cooled condenser). Clogged spray nozzles

(evaporative condenser). Dirty tube and fin surface (air cooled condenser).

3. Noncondensables in system.

4. System overcharge with refrigerant.

5. Discharge shutoff valve partially closed.

7. High ambient conditions.

1.

2.

5.

2.

Liquid line solenoid will not open.

Flooding of refrigerant into crankcase. liquid line.

Faultly condenser temp. regulation.

Insufficient refrigerant in system.

Low ambient conditions.

Expansion valve overfeeding.

1. Lack refrigerant.

2. Check electrical circuits and motor winding for shorts or grounds.

Investigate for possible overloading.

Replace fuse or reset breakers after fault is corrected.

3. Overloads are auto reset. Check unit closely when unit comes back on line.

4. Repair or replace.

5. Determine type and cause of shutdown and correct it before resetting protection switch.

6. None. Wait until unit calls for cooling.

7. Repair or replace coil.

8. Check motor for opens, short circuit, or burnout.

9. Check all wire junctions. Tighten all terminal screws.

1. Check superheat setting of expansion valve.

2. Relocate, add or remove hangers.

3. Replace.

1. Readjust temperature control or water regulating valve. Investigate ways to increase water supply.

2. Clean.

4. Remove excess refrigerant.

6. Check condenser rating tables against the operation.


1. Check condenser control operation.

2. Check for leaks. Repair and add charge.

3. See corrective steps for low suction pressure below.

4. Check condenser rating table against the operation.


1. Reduce load or add additional equipment.

2. Check remote bulb. Regulate superheat.

1. Check for leaks. Repair and add charge.

Low Suction

Pressure

3. Clogged liquid line filter-drier.

4. Clogged suction line or compressor suction gas strainers.

5. Expansion valve malfunctioning.

6. Condensing temperature too low.

7. Compressor will not unload.

5. Check and reset for proper superheat.

Replace if necessary.

6. Check means for regulating condensing temperature.

7. See corrective steps for failure of compressor to unload.

Little or No Oil

Pressure

1. Clogged suction oil strainer.

2. Excessive liquid in crankcase.

4. Flooding of refrigerant into crankcase.

1. Clean.

2. Check crankcase heater. Reset expansion valve for higher superheat.

Check liquid line solenoid valve operation.

4. Adjust thermal expansion valve.


PROBLEM

Compressor

Loses Oil

Motor Overload

Relays or Circuit

Breakers Open

Compressor

Thermal Switch

Open

Freeze Protection

Opens

POSSIBLE CAUSES

1. Lack refrigerant.

2. Velocity in risers too low (A-C only).

3. Oil trapped in line.

1. Low voltage during high load conditions.

2. Defective or grounded wiring in motor or power circuits.

3. Loose power wiring.

4. High condensing temperature.

5. Power line fault causing unbalanced voltage.

6. High ambient temperature around the overload relay

1. Operating beyond design conditions.

2. Discharge valve partially shut.

1. Thermostat set too low.

POSSIBLE CORRECTIVE STEPS

1. Check for leaks and repair. Add refrigerant.

2. Check riser sizes.

3. Check pitch of lines and refrigerant velocities.

1. Check supply voltage for excessive line drop.

3. Check all connections and tighten.

4. See corrective steps for high discharge pressure.

5. Check Supply voltage. Notify power company. Do not start until fault is corrected.

6. Provide ventilation to reduce heat.

1. Add facilities so that conditions are within allowable limits.

1. Reset to 42°F (6°C) or above.

3. See “Low Suction Pressure.”

Warranty Statement

Limited Warranty

Consult your local McQuay Representative for warranty details. Refer to Form 933-

43285Y. To find your local McQuay Representative, go to www.mcquay.com.


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.

Post Office 2510, Staunton, Virginia 24402 USA • (800) 432-1342 • www.mcquay.com OM WGZ-1 (3/05)

No results