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13.5 Com m issioning
Com m issioning Step One
1. Remove the main fuses or switch off the circuit breakers for the compressor.
2. Switch on the main isolator on the unit.
3. Switch on each system, individually; checking as the systems are brought on that fans, lights etc. are operating
properly. Check liquid solenoid valves operation and rotation of condenser fans (when fitted). When satisfied that
all systems are functioning, switch off main supply.
4. Replace compressor fuses or switch on circuit breaker for the lead compressor only to ensure all systems are
refrigerating during commissioning.
5. If additional oil is needed, please add through the valve in 1st stage suction line.
6. Switch on the main isolator. Providing enough refrigerant is in the system, the lead compressor will start up and
adding more refrigerant to the plant can commence.
Com m issioning Step Tw o
Charging of the system should continue until the receiver is approximately 25% full, and the discharge pressure
approaching design value. When this condition has been reached, shut off all charging cylinders and allow the
compressor to run normally.
Check now that all the systems/stubs are refrigerating satisfactorily, evaporators fully frosted etc.
Com m issioning Step Three
Now replace remaining compressor fuse circuit breakers and allow electronic compressor controller to stage in
compressors as required.
Com m issioning Step Four
During the general commissioning the following electrical items should be checked:
1. Sub fuses, circuit breakers correct.
2. Main fuses, circuit breakers are correct and balanced.
3. Main compressor fuses and circuit breakers are correct.
4. All cable connections are tight.
5. Motor starter controls/contactor overloads are set correctly.
6. Check all contactors operate correctly.
13.6 Operational Check out
When the system has been charged and has operated for at least 2 hours at normal operating conditions without
any indication of malfunction, it should be allowed to operate overnight on automatic controls. Then a thorough re-
check of the entire system operation should be made as follows:
1. Check the unit head and suction pressures. If the pressures are not within the system design limits, determine
why and take corrective action.
2. Check the liquid line sight-glass and expansion valves operation. If there are indications that more refrigerant is
required, leak test all connections and system components and repair any leaks before adding refrigerant.
3. Expansion valves must be checked for proper superheat settings.
Expansion valve probes must be in positive thermal contact with suction lines.
Valves with high superheat settings produce little refrigeration and poor oil return.
Too little superheat causes low refrigerant capacity and promotes liquid slugging and compressor oil removal.
LIQUID REFRIGERANT MUST BE PREVENTED FROM REACHING THE COMPRESSOR.
4. Using suitable instruments carefully check line voltage and amperages at the compressor terminals. Voltage
should be within 10% of the nameplate voltage.
Copyright HPL March 2021
P4114S Rev 03
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