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Chiller Water-cooled Screw
M1 contactor, M2 contactor and M3 contactor indicates condition of electron contactor for compres-
sor with input display. The value indicated on Output display is Output from actual PLC, the value
indicated on Input display is extra contact part condition which is inputted to PLC from electron con-
tactor. Therefore, if wiring related to electron contactor is normal, the condition should be consistent.
If input condition and output condition is not same due to abnormality of electron contactor, it recog-
nize the situation of alarm generation by PLC.
Loading Solenoid valve and Unloading Solenoid valve is used to control the sliding valve for volume
control of the compressor. Loading Valve and Unloading Valve is used to control Sliding Valve by
using oil pressure for compressor.
Liquid Solenoid valve is valve for Economizer operation, and it is installed at the pipe that sprays the
mid-pressure refrigerant to middle of compressor rotor, and it sprays when it is ON. If it is normal,
Liquid Solenoid valve is ON and spray refrigerant 100% in operating condition.
Pump contactor output is output signal for control cold water and cooling water, it should conduct
pump control of cold water and cooling water pump in field by field wiring. At least field pump should
be kept operating when this output signal is ON.
Alarm Output is the signal that operator can check the alarm operation of chiller in location where it
is far from chiller installation field and gives output when alarm is ON. If this signal is ON, chiller has
alarm operation, if the signal is OFF, chiller has normal condition.