v. 3.0
Reference guide
Compressor Control Module CM-RC-01
3.0
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4.1.3.2
Liquid injection cooling (CIC)
CIC is a cooling system to reduce the discharge gas temperature. The control algorithm for the
liquid injection cooling in the CM-RC-01 starts the CIC if the discharge gas temperature gets too
high.
4.1.4
Capacity control
The CM-RC-01 can control the needed capacity of the compressor by controlling the CRII valves.
The 0
– 10 V
Cap. In
input or the Modbus parameter
Serial setpoint
(see section 0 ) can be used
to specify the needed capacity of the compressor. The compressor must be mounted with a CRII
capacity regulation system.
The CM-RC-01 will operate the CRII valve(s) to achieve the requested capacity with as little
pressure fluctuations as possible.
The capacity range is 10 % - 100 %.
When liquid injection cooling (CIC) needs to run due to high discharge temperature, the capacity
system will be forced to run with a certain minimum capacity, in order to avoid flooding of the
compressor.
4.2
Monitoring and diagnosis
4.2.1
Motor temperature
One of the functions of the CM-RC-01 is to protect the compressor motor against overload.
By monitoring the resistance in a PTC sensor mounted in the motor windings, the CM-RC-01 will
lockout and stop the motor if the resistance increases above the limit as shown below.
When the lockout has been activated, the two start relays K1 and K2 are released immediately to
stop the compressor.
There is a restart blocking function to prevent the motor from being started too soon after having
been overheated.
