©2025 Copeland LP.
026-1803 R13 Supervisor I&O User Guide 9 - 10
9.7.3 The Enhanced Suction Group
Application
A Suction Group application looks at suction pressure or
suction temperature and compares it to the suction setpoint
to determine whether compressor stages should be cycled
ON or OFF. Unlike the Suction Group application, which uses
a PID percentage to determine how many stages to turn ON
or OFF, the Enhanced Suction Group keeps historical data of
the effects each compressor stage has on the suction
pressure or temperature, and analyzes that data to determine
which stages to cycle.
The Enhanced Suction Group application is designed to
balance tight control of suction pressure with economic
management of compressor cycling to reduce power usage
and compressor wear.
9.7.3.1 Learning Mode
When an Enhanced Suction Group application runs for the
first time, it undergoes a “Learning Mode” period to collect
data on the compressor stages. During Learning Mode, the
Enhanced Suction Group will control suction pressure, but it
will purposely cycle the compressor stages in different
combinations to measure the effect they have on the suction
input value.
The Learning Mode lasts for several minutes. After
Learning Mode ends, the Enhanced Suction Group will
require up to 24 hours of operation before compressor
cycling is operating at maximum efficiency. If compressor
cycling seems too frequent after 24 hours of operation, you
may reduce compressor cycling by changing the Control/
Cycles parameter (see Section 9.7.3.3, The Control/Cycles
Parameter).
9.7.3.2 Circuit Load Analysis
Unlike the standard Suction Group algorithm, the Enhanced
Suction Group includes Circuit Setup where you associate all
circuits connected to the suction group. Once the circuits are
set up, the suction group will use the circuit states to help
determine current loads on the suction group. For example,
when one or more circuits go into defrost, the Enhanced
Suction Group determines that there is less of a load on the
suction group than if all circuits were in refrigeration. With the
appropriate circuits associated, the Enhanced Suction Group
tailors
its capacity to meet the load. Over time, the Enhanced
Suction Group will build and store a profile
for all the
different combinations of circuit states encountered in the
algorithm.
9.7.3.3 The Control/Cycles Parameter
Unlike the standard Suction Group, which used PID
constants as a means of optimizing suction control and had
limited features for controlling compressor cycle counts, the
Enhanced Suction Group has one parameter with five preset
settings to allow users to alter suction control performance or
compressor cycling frequency.
The default setting, “Moderate Control,” seeks to balance
good suction pressure control with efficient cycling. If tighter
control is needed, setting the field to “Tight Control” or
“Tightest Control” will increase the application’s reaction to
suction changes, resulting in tighter control (usually at the
expense of more frequent cycling). If fewer compressor
cycles are desired, setting the field to “Less Cycling” or “Least
Cycling” will decrease the number of cycles but also increase
the amount of fluctuation in the suction pressure.
9.7.3.4 Variable-Speed, Digital Scroll, and
Digital Discus Compressor Support
The Enhanced Suction Group supports variable-speed
compressors similar to the Suction Group application. When
a variable-speed compressor is present, it is the first
compressor stage ON and the last stage OFF, and its capacity
is varied to attempt to correct small fluctuations in the suction
pressure or temperature.
In addition, the Enhanced Suction Group application
supports use of one or multiple Copeland Digital Scroll or
Digital Discus compressors for use as a variable-capacity
compressor. With several Digital Scroll or Digital Discus
compressors, the Enhanced Suction Group will modulate
one of those compressors at a time to control suction
pressure. As compressor capacity is added or removed, the
Enhanced Suction Group may modulate another Digital
Scroll compressor to distribute compressor resources and
solenoid wear.
The operating capacities of the Copeland Digital Scroll and
Copeland Digital Discus compressors are determined in the
same way as a variable-speed compressor, except the
Copeland Digital Scroll and Copeland Digital Discus
controlled by pulse-width modulation (PWM).
9.7.3.5 Floating Suction Control
Floating suction control in the Enhanced Suction Group
behaves identically to the way it works in the Suction Group
application. Refer to Section 9.7.2.3, Floating Setpoint Control.
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