from OPI AE8

from OPI AE8
AE21-1355 R2
AE21-1355 R3
November 2011
Digital Capacity Control for Copeland® and Intelligent Store Discus™
Refrigeration Compressors
Introduction
blocked to all cylinders on a single bank; therefore there
is no gas to compress and the power consumption is
significantly lower. The unloader piston mechanism
that controls flow of suction gas into the cylinders is
driven by a solenoid valve. See the descriptions and
figures below for the unloaded and loaded states for
Copeland Discus Digital operation.
On refrigeration applications where the load may vary over
a wide range, some means of capacity control is often
desirable for optimum system performance and control.
In addition, compressor capacity modulation can reduce
power and energy consumption, reduce compressor
cycling, and decrease the starting electrical load. In
order to achieve the above objectives, Emerson Climate
Technologies has developed Copeland Discus Digital™,
a method for variable capacity in Discus® compressors.
Digital technology will, for the first time, permit digital
modulation of Discus compressors for high, medium,
and low temperature applications.
Digital technology is now also available on the 4D
and 6D Discus compressors. Applied to one bank
of the compressor it can provide 50-100% capacity
modulation on a 4D Discus and when combined with
a blocked suction bank on a 6D can provide 33-100%
capacity on a 6D (without the blocked suction bank
67-100% digital modulation is available on the 6D
platform).
Theory of Operation
Digital capacity control is achieved by using a proven
internal unloading method, blocked suction. Blocked
suction has been applied to multiple bank compressors
in the past, but digital modulation allows the technology
to apply to single bank compressors as well, such as
the 3D. By varying the percentage of duty cycle that
the compressor is loaded and unloaded, capacity
control between 10 and 100% can be achieved. During
blocked suction operation, the flow of suction gas is
Note! 6D Discus Digital(TM) is only available on the
Intelligent Store Discus v2.x platform.
Figure 1: Unloaded Operation
1. Enters Compressor
2. Passes Through Body
3. Unloader Mechanism Blocks Gas Before
Entering Valve Plate
1
3
2
Figure 1
Copeland Discus Digital Unloaded Operation (Shown on a Copeland 3D Discus)
© 2010 Emerson Climate Technologies
Printed in the U.S.A.
1
AE21-1355 R2
Figure 2: Loaded Operation
1. Enters Compressor
2. Passes Through Body
3. Into Valve Plate
4. Compressed by Pistons
5. Exits Compressor
envelopes. The head fan, return gas and oil cooler
requirements are the same as those for the standard
Discus compressors.
Control
Capacity modulation is achieved by energizing and deenergizing the solenoid valve. When the solenoid valve
is de-energized, the compressor capacity is 100%.
When the solenoid valve is energized, the compressor
capacity is zero. Therefore, the capacity achieved is
the time average capacity, which is a variable from 10
– 100% on a 3D. Example: If you have a 20-second
cycle and the solenoid is de-energized for 16-seconds,
and then energized for 4-seconds, the resulting
capacity will be approximately 80%.
Nomenclature
The Copeland Discus Digital™ compressor model
numbers are designated by a “D” or an “X” in the fourth
character, e.g. 3DSDR17ME-TFD, 4DADF47KETSK or 4DJXR28ME-TSK. Discus digital model
numbers include additional information about the
compressor, consistent with the standard Discus
model nomenclature.
For more information on available Discus digital models
visit the website www.emersonclimate.com or contact
your Emerson Climate Technologies representative.
For 4D/6D Models one bank of the compressor
remains loaded 100% while the digital bank will
modulate 0-100% to provide the additional capacity.
On a 6D with blocked suction the blocked suction bank
will unload when demand capacity is less than 67%
and load when the demand capacity is higher than
67%. The Digital bank will continue to load and unload
providing continuous capacity across the 33-100%
range.
Digital Performance
The nominal power consumption per nominal capacity
output varies. An example of the power required as a
percent of load is shown in Figure 3 for a 3D Discus
digital.
Operating Envelope
Note! 6D Discus Digital is only available on Intelligent
Store Discus v2.x compressors.
The operating envelopes for Discus digital compressors
are the same as the standard Discus compressor
5
(From Discharge)
4
1
3
2
Figure 2
Copeland Discus Digital Loaded View (shown on a Copeland 3D Discus)
© 2010 Emerson Climate Technologies
Printed in the U.S.A.
2
AE21-1355 R2
100%
90%
Percentage of Full Power
80%
70%
60%
50%
40%
30%
20%
10%
0%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Percentage of Full Capacity
Figure 3
Typical Modulated Power Reduction (for 3D Discus Digital )
Seconds
20 Second Operating Cycle (Based on 3D Discus Digital)
90%
85%
80%
75%
70%
65%
60%
55%
50%
45%
40%
35%
30%
25%
20%
15%
10%
Load
Load
Load
Load
Load
Load
Load
Load
Load
Load
Load
Load
Load
Load
Load
Load
Load
Digital Bank
Loaded
Digital Bank
Unloaded
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Figure 4
% Loaded vs Time
© 2010 Emerson Climate Technologies
Printed in the U.S.A.
3
AE21-1355 R2
Control Requirements with Copeland® Digital
Compressor Controller
Note! For more information on the Copeland(R) Digital
Compressor Controller refer to the application guidelines
in AE8-1328, Copeland® Digital Compressor Controller.
The Digital Compressor Controller is an electronics
interface between the Copeland Discus Digital
compressor and the system controller. The system
controller measures temperature or pressure to calculate
the needed compressor capacity and communicates
that capacity to the Digital Compressor Controller via
an analog signal.
Four #10 self tapping sheet metal screws, at least
½” length, are required for installation. The maximum
mounting screw torque is 20 in. lbs. Locate the Digital
Compressor Controller inside the electrical enclosure
near the compressor contactor (wire routing for
compressor power wiring will be easier in this position).
The maximum wire terminal screw torque is 7 in. lbs.
The Digital Compressor Controller will operate in any
mounting orientation where the green power LED is
at the top. Mount the Digital Compressor Controller
such that all LEDs are visible from a comfortable
viewing position. A service panel label (Form
2003CC-80) describing the terminals and ALERT
flash codes is included with each Digital Compressor
Controller. This label should be in a visible location
for the technician when troubleshooting the system.
Width: 2.0”
(51 mm)
Height:
4.0”
(102 mm)
Compressor Wiring
The Digital Compressor Controller senses compressor
motor current for diagnostics and protection. The
Depth: 6.0” (153 mm)
**
1-5VDC DEMAND
SIGNAL FROM
SYSTEM
CONTROLLER
24VAC
CONTROLLER
POWER
24COM
24VAC
C1
COMMON
+5VDC
SIGNAL
U3/V1
C2
C3
COMMON
P1
SIGNAL
+5VDC
SUPPLY
P2
OPTIONAL
0-5VDC
SUCTION
PRESSURE
OUTPUT
U1
P3
M2
P4
M1
COMMON
P5
+5VDC
P6
L2
T1
L1
T2
DISCHARGE
TEMPERATURE
THERMISTOR
OR 5kOhm, 1 W RESISTOR
(for Demand Cooling Applications)
*
**
A1
T4
T5
A2
T6
COMPRESSOR POWER
WIRE T1/C
Compressor Controller Wiring Diagram
© 2010 Emerson Climate Technologies
Printed in the U.S.A.
4
*
LINE
CONTACTOR
COIL
CONTROL
VOLTAGE
24-250VAC
NEUTRAL
T3
Protection controls such as high/low pressure controls
and compressor motor protection module go here.
Polarity must match system controller.
Note: The Neutral to L1, M1, U1, V1 is connected together.
DIGITAL
UNLOADER
SOLENOID
U2
C4
OPTIONAL
SUCTION
PRESSURE
TRANSDUCER
INPUT
OPTIONAL
VAPOR INJECTION
SOLENOID OR
BLOCKED SUCTION
UNLOADER (6D)
U4/V2
ALARM
RELAY
OUTPUT
AE21-1355 R2
compressor motor leads must be run through the
holes in the plastic housing for a current transformer to
sense motor current.
The minimum load and unload times should be limited
to 2 seconds. These described load and unload times
will give the compressor an operating range during
a 20 second cycle from 10% load up to 90% load
(on 3D only – 4D and 6D minimum percent capacity
would be 50%, 33% or 67% depending on compressor
configuration). The compressor can also operate at
a 100% load for the full modulation sequence. The 2
seconds minimum times will give the unloader piston
assembly time to both load and unload fully.
For Three Phase 3D Discus® compressors: the
compressor’s T1, T2 and T3 wires must be routed
through the holes in the Digital Compressor Controller
module marked “T1,” “T2” and “T3.” The Digital
Compressor Controller module is phase insensitive
and will NOT detect reverse phasing of the compressor.
NOTE! Do not bundle low voltage wires with
compressor power or high voltage wires.
If the load required is less than 10% minimum percent
capacity of the digital compressor (10% for 3D, 50%
for 4D or 33% or 67% for 6D) the compressor motor
should be shut down. Restarting of the compressor
will be governed by the capacity rising above the10%
minimum percent capacity or more based on a
modulation time of 20 seconds, and by the motor
starting logic.
NOTE! Attach cable ties through loops on side of the
housing for wire strain relief.
Control Requirements with Intelligent Store
Discus™ v2.x
Discus Digital compressors are also compatible with
Intelligent Store™ v2.1 and newer technology. Using
Intelligent Store Discus™ eliminates the need for the
separate Copeland® Digital Compressor Controller
in system wiring. NOTE! Discus Digital is not
compatible with Intelligent Store Discus 1.0.
Solenoid Valve/Gaskets
Due to the high life cycle requirements in a hot gas
environment, a special valve has been developed.
Due to reliability requirements, only Emerson solenoid
valves may be used. All compressor warranties are null
and void if the Emerson valve is not used. Solenoid
coils will be sold separately for all non-Intelligent Store
Discus orders. See Table 1 for the appropriate solenoid
kit number for your application. Furthermore, Discus
digital compressors use special head and valve plate
gaskets which have modifications to ensure gas flow
for proper digital modulation. Only Emerson approved
gaskets may be used. All compressor warranties are
null and void if the Emerson gaskets are not used.
Master Controller
The Copeland Discus Digital™ compressor is approved
for use with E2 v2.3 facility management system and
higher. The compressor should be specifically identified
as digital in the E2 in the staging setup. For any other
system controllers please check with your Application
Engineer. If using a Discus digital compressor with
Intelligent Store Discus™ v2.x with the E2 system
controller, E2 v 2.6 or newer is required. You do not
need the Digital Compressor Controller when using
Intelligent Store Discus™. More information on the E2
system controller can be found in the E2 User Manual
available at http://www.emersonclimate.com/enUS/products/controls/facility_controls/e2/rx.aspx.
For additional information on Intelligent Store Discus
v2.1 refer to the application guidelines in AE8-1368,
Intelligent Store Discus™ 2.1.
Table 1
Kit Part Number
24V
923-0084-00
120V
923-0084-01
240V
923-0084-02
Thermistor
Recommended Application Settings for
the Modulation on Copeland Discus Digital
Compressors
The thermistor must conform to the curve characteristics
outlined in Table 2. The table expresses the ratio of
the resistance at the indicated temperature and the
resistance at 25°C (77°F). The resistance at 25°C
(77°F) is 86K ohms nominal. The curve fit is: Ratio =
0.8685e-0.0257x. Warning: this curve fit is only valid
for temperature range of 100 to 160°C (212-320°F).
The system design should follow the required and
recommended guidelines as detailed in the various
Application Engineering Bulletins, which can be
found on the website at www.emersonclimate.com.
The compressor motor should only be restarted after
an appropriate time delay. The digital modulation
cycle time recommended is 20 seconds; for other
values, check with your Application Engineer.
© 2010 Emerson Climate Technologies
Printed in the U.S.A.
Solenoid Coil Voltage
Multiple Compressor Application
To ensure smooth and continuous modulation,
selection of the digital and non-digital compressor
5
AE21-1355 R2
capacities can be made according to the following rule.
General Guidelines and More Information
Rule: For optimum suction pressure control, the
following guideline is recommended in the selection
of Discus digital and fixed compressors, per suction
header:
For general Discus® compressor and digital control
guidelines please log in to Online Product Information
at www.emersonclimate.com, refer to the Application
Engineering Bulletins listed below, or contact your
Application Engineer.
- D > F1
- F2 < D+F1
- F3< D+F1+F2
-….
-FN<D+F1+2+….FN-1
AE4-1135
Cooling Requirements for
Copelametic® Compressors
AE4-1287 Copeland Discus® Demand Cooling
AE4-1334 Low Condensing Temperature Bulletin
In the above equations, D is digital Discus capacity
or horse power, F1,…FN are the standard Discus
compressor capacity or horse power. The compressor
selected should be the smallest compressor capacity
that still covers all the gaps between steps to ensure
the most efficient system control.
AE8-1328 Copeland® Digital Compressor
Controller
AE8-1351 Intelligent Store Discus™ 2.0
AE4-1357 Upgrade Procedures for Digital
Capacity Control for Copeland Discus®
Refrigeration Compressors
When using this rule keep in mind the digital range,
for example on a 4D you have continuous capacity
from 50 to 100%, therefore when selecting a 4D digital
compressor you should have a fixed compressor
behind it that is 50%-100% of the full load of the digital
compressor. For example, if a 4DADF47KL-TFD (full
capacity is about 47,000 Btu per hour, 50% capacity is
about 23,500) is chosen a standard 3DA3F28KL-TFD
(full capacity is about 28,000 Btu per hour) could be
chosen as the second compressor stage behind the
digital compressor.
Note! For best results, the digital compressor needs to
be the lead compressor. It must be the first compressor
on and last compressor off in multiple compressor
applications.
Example:
Cooling
Demand (HP)
Load = 0
10.10 < Load < 17.50
17.10 < Load < 25
23.10 < Load < 31.50
Digital
(HP)
OFF
Fixed
(HP)
OFF
Fixed
(HP)
OFF
Fixed
(HP)
OFF
System
Output (HP)
0
0.10 - 10
0.10 - 10
0.10 - 10
7.5
7.5
7.5
OFF
7.5
7.5
OFF
OFF
7.5
10.10 -- 17.50
17.10 -- 25
23.10 -- 31.50
© 2010 Emerson Climate Technologies
Printed in the U.S.A.
6
AE21-1355 R2
Table 2
Temperature and Resistance Ratio for Thermistor
Temperature Sensor Resistance Values
Temp
-40°C
-39°C
-38°C
-37°C
-36°C
-35°C
-34°C
-33°C
-32°C
-31°C
-30°C
-29°C
-28°C
-27°C
-26°C
-25°C
-24°C
-23°C
-22°C
-21°C
-20°C
-19°C
-18°C
-17°C
-16°C
-15°C
-14°C
-13°C
-12°C
-11°C
-10°C
-9°C
-8°C
-7°C
-6°C
-5°C
-4°C
-3°C
-2°C
-1°C
0°C
1°C
2°C
3°C
4°C
Ratio
33.60000
31.44900
29.45200
27.59700
25.87300
24.27000
22.76100
21.35700
20.05100
18.83400
17.70000
16.63420
15.64040
14.71340
13.84820
13.04020
12.28070
11.57100
10.90750
10.28680
9.70600
9.15880
8.64630
8.16620
7.71620
8.29400
6.89570
6.52190
6.17110
5.84150
5.53190
5.23920
4.96400
4.70520
4.46170
4.23240
4.01530
3.81090
3.61820
3.43670
3.26540
3.10300
2.94980
2.80520
2.66860
Temp
5°C
6°C
7°C
8°C
9°C
10°C
11°C
12°C
13°C
14°C
15°C
16°C
17°C
18°C
19°C
20°C
21°C
22°C
23°C
24°C
25°C
26°C
27°C
28°C
29°C
30°C
31°C
32°C
33°C
34°C
35°C
36°C
37°C
38°C
39°C
40°C
41°C
42°C
43°C
44°C
45°C
46°C
47°C
48°C
49°C
© 2010 Emerson Climate Technologies
Printed in the U.S.A.
Ratio
2.53960
2.41710
2.30130
2.19180
2.08830
1.99030
1.89720
1.80900
1.72550
1.64640
1.57140
1.50000
1.43230
1.36810
1.30710
1.24930
1.19420
1.14180
1.09210
1.04490
1.00000
0.95710
0.91640
0.87760
0.84070
0.80560
0.77200
0.74010
0.70960
0.68060
0.65300
0.62660
0.60140
0.57740
0.55460
0.53270
0.51170
0.49180
0.47270
0.45440
0.43700
0.42030
0.40420
0.38890
0.37430
Temp
50°C
51°C
52°C
53°C
54°C
55°C
56°C
57°C
58°C
59°C
60°C
61°C
62°C
63°C
64°C
65°C
66°C
67°C
68°C
69°C
70°C
71°C
72°C
73°C
74°C
75°C
76°C
77°C
78°C
79°C
80°C
81°C
82°C
83°C
84°C
85°C
86°C
87°C
88°C
89°C
90°C
91°C
92°C
93°C
94°C
Ratio
0.36030
0.34690
0.33400
0.32170
0.30990
0.29860
0.28780
0.27740
0.26750
0.25790
0.24880
0.24000
0.23150
0.22350
0.21570
0.20830
0.20110
0.19430
0.18760
0.18130
0.17520
0.16930
0.16370
0.15820
0.15300
0.14800
0.14310
0.13850
0.13400
0.12970
0.12550
0.12150
0.11770
0.11400
0.11040
0.10700
0.10370
0.10050
0.09740
0.09440
0.09150
0.08885
0.08610
0.08355
0.08108
7
Temp
95°C
96°C
97°C
98°C
99°C
100°C
101°C
102°C
103°C
104°C
105°C
106°C
107°C
108°C
109°C
110°C
111°C
112°C
113°C
114°C
115°C
116°C
117°C
118°C
119°C
120°C
121°C
122°C
123°C
124°C
125°C
126°C
127°C
128°C
129°C
130°C
131°C
132°C
133°C
134°C
135°C
136°C
137°C
138°C
139°C
140°C
141°C
142°C
Ratio
0.07870
0.07641
0.07420
0.07206
0.07000
0.06800
0.06612
0.06430
0.06255
0.06085
0.05920
0.05760
0.05605
0.05456
0.05310
0.05170
0.05027
0.04889
0.04755
0.04625
0.04500
0.04372
0.04248
0.04128
0.04012
0.03900
0.03793
0.03690
0.03590
0.03494
0.03400
0.03315
0.03233
0.03153
0.03075
0.03000
0.02926
0.02854
0.02784
0.02716
0.02650
0.02586
0.02525
0.02465
0.02407
0.02350
0.02295
0.02242
Temp
143°C
144°C
145°C
146°C
147°C
148°C
149°C
150°C
151°C
152°C
153°C
154°C
155°C
156°C
157°C
158°C
159°C
160°C
161°C
162°C
163°C
164°C
165°C
166°C
167°C
168°C
169°C
170°C
171°C
172°C
173°C
174°C
175°C
176°C
177°C
178°C
179°C
180°C
181°C
182°C
183°C
184°C
185°C
186°C
187°C
188°C
189°C
190°C
Ratio
0.02190
0.02139
0.02090
0.02039
0.01990
0.01942
0.01895
0.01850
0.01801
0.01754
0.01708
0.01663
0.01620
0.01584
0.01549
0.01515
0.01482
0.01450
0.01418
0.01388
0.01358
0.01328
0.01300
0.01275
0.01250
0.01226
0.01203
0.01180
0.01157
0.01134
0.01112
0.01091
0.01700
0.01049
0.01029
0.10090
0.00989
0.00970
0.00949
0.00928
0.00908
0.00889
0.00870
0.00853
0.00837
0.00821
0.00805
0.00790
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