Flooded type water cooled screw chiller (PCB Control)
36
electric control wiring diagram for detail connection information.
Thermistor replacement
To Replace Thermistors RT1, RT2, RT3, RT4, RT5, or RT6 (Entering/Leaving chilled Water;
Entering/Leaving cooling Water; Discharge Temperature; Oil temperature)
— Disconnect appropriate
connector from the PCB controller. New thermistors should be spliced to existing wiring close to the
connector unless new connectors are required. Remove thermistor cable from harness. Remove and
discard original thermistor from well. Insert new thermistor in well body to its full depth. Add a small
amount of thermal conductive grease to thermistor probe and well. Tighten the screw to prevent
thermistors from slipping out of the well.
To Service Compressor Motor Thermistors
A thermistor is factory installed in each compressor. Connections for the thermistors are located in the
compressor wiring box. 2 terminals are reserved for the thermistor: S1 and S2. Motor temperature is
measured by leads connected to S1 and S2 terminal. The thermistors are not serviceable in the field. If
the compressor motor thermistor fails, compressor replacement is required.
2).pressure sensors
The
pressure
sensors
are
pressure
transmitters.
Danfoss
AKS3000
are
used.
Water temp. thermistor
suction temp. thermistor
pressure transmitter AK3000
5.
Parts control
1). Oil heater control
In unit sand by period, oil heater is energized to keep normal oil temperature. When unit starts, it is
turned off.
Oil heating time limits:
When cooling water inlet temperature >= 35°C (real time value), oil heating time for first startup
is 0.5h. If power down happens during operation and downtime is less than 8hrs, no heating
time delay is needed when unit restarts. If it exceeds 8hrs, 0.5h heating time is need.
When cooling water inlet temperature >= 30°C (real time value), oil heating time for first startup
is 1h. If power down happens during operation and downtime is less than 5hrs, no heating time
delay is needed when unit restarts. If it exceeds 5hrs, 1h heating time is need.
When cooling water inlet temperature >= 25°C (real time value), oil heating time for first startup
is 2hrs. If power down happens during operation and downtime is less than 3hrs, no heating
time delay is needed when unit restarts. If it exceeds 3hrs, 1h heating time is need. If it exceeds
5hrs, 2hrs heating time is need.
