Carel MuChiller UCHBD00001130, User Manual

Page: 72 / 108

ENG
Fig.5.z
Key
Defrost Defrost request
4WV Cycle reversal (4-way valve)
CP Compressor capacity
Fan Enable fans
EEV Electronic expansion valve
The control phases are described below.
Synchronisation (1)
Once the defrost start condition is true, there is a fixed delay of 10 s to check whether the other circuit
requires defrosting, so as to carry out a simultaneous defrost if needed.
User Code Description Def Min Max UOM
S S053
Defrost synchronisation
0=Independent
1=Separate
2=Simultaneous
40.0 0.0 999.9 rps
Decrease capacity to start defrosting (2)
In this phase, the circuit with BLDC compressor decreases capacity to the minimum set value; with on-off
compressors, one compressor is stopped.
User Code Description Def Min Max UOM
S S052 BLDC compressor speed for cycle reversing in defrost 40.0 0.0 999.9 rps
Waiting time before reversing the cycle (3)
The compressor remains at the cycle- reversal speed for a set time: with the BLDC compressor, the
duration of this phase is increased by the time needed to reach minimum speed. The other control
devices, such as the cycle reversing valve and the fans, continue to operate in heat pump mode.
User Code Description Def Min Max UOM
S S044 Operation time at min capacity before cycle reversing 20 0 999 s
Cycle reversal and waiting time after reversal (4)
The 4-way valve is positioned in chiller mode to run the defrost, the fans are stopped and the compressor
remains at the cycle-reversal speed for 5 seconds. Normally during this phase the electronic expansion
72 | 5. Functions
µC0300053EN rel. 1.0 – 23.07.2018