Unit Protection Module (UPM)
The Unit Protection Module (UPM) as shown in figure 1, is a printed circuit board (PCB) that
interfaces with the thermostat or the digital direct controller.
The main purpose of this device is to protect the compressors by monitoring the different states
of switches and sensors of each refrigerant circuit, this device provides time delays and protects
the unit against freezing of the water and refrigerant heat exchangers as well as condensate
overflow when the appropriate sensors are installed.
Figure 1 - UPM Two Stage
Alarm output is Normally Open (NO) dry contact. If 24 VAC output is needed R must be wired to
the ALR-COM terminal; 24VAC will be available on the ALR-OUT terminal when the unit is in
alarm condition. If pulse is selected the alarm output will be pulsed.
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