Rev 07/04/2015
14
3.3. PRESSURE SWITCH
There is a pressure regulating switch installed to prevent compressor failures or improper
operation due to high discharge pressure. Self contained models have a high pressure
switch only, while remote units have a double switch, like the one shown below. In the old
models both types of application had a double switch, triggering alarm “hp” either for a low
or high pressure event. In some recent remote application, the pressure switch is used for
pump down purpose also.
3.3.1 Pressure Switch Working Principles – Alarm Connection
The pressure switch has normally closed contacts that will open if the High or Low
pressure limits are exceeded. The switch is connected to the Main Board at terminals 48 &
50 in case of standard controller (48 is a shared connection with the door switch), and
terminals GND & D1 in Touch Screen version. When the pressure switch opens from
either a high or low pressure condition, the display will show the error code “hP” (or
message “HIGH PRESSURE” in Touch screen version).
OUT PRESSURE
VERSION
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