SRC Service Manual
Revision 02
Aug 2007
3.3.6 High
Pressure
Switch
Settings: On: 406 psig (28 barg), Off: 305 psig (21 barg).
Shuts down the dryer in the event of overpressure of the
refrigerant system. Installed at the compressor outlet. When it
trips, the display will show the HP (High Pressure) alarm, and
the remote alarm contacts will be activated.
On the SRC-150 to 200 the switch must be reset manually by
pushing the red button when the pressure is below 305 psig
(21 barg).
On the SRC-250 to 1000 the switch automatically resets when
the pressure goes back below 305 psig (21 barg).
See Section 10 for details on troubleshooting an HP (High Pressure) alarm.
3.3.7 Low Pressure Switch
Settings: On: 21.7 psig (1.5 barg), Off: 36.2 psig (2.5 barg).
The SRC-250 to 100 have a Low Pressure Switch to shut down the dryer in the
event of low pressure at the compressor inlet, as this indicates a refrigerant
temperature below freezing. The microprocessor has a delay of 5 minutes before
going into alarm. When this 5 minutes has passed, the display will show the LP
(Low Pressure) alarm, and the remote alarm contacts will be activated.
The switch automatically resets when the pressure returns above 36.2 psig.
See Section 10 for details on troubleshooting an LP (Low Pressure) alarm.
3.3.8 Fan Pressure Switch
Settings: On: 261 psig (81 barg), Off: 203 psig (14 barg).
Controls operation of the condenser fan which keeps the pressure (and therefore
temperature) of the refrigeration circuit within design limits. Turns the fan on when
the refrigerant pressure reaches 261 psig (18 barg) and off when it reaches 203
psig (14 barg).
On single phase units the switch controls the fan motor directly. On
three phase units, the switch sends a signal to a contactor which controls the fan
motor.
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