Alpha Technologies Radium MiniBay - Manual (Page 25)

25 044-001-C0-00, Rev. C
2.0 DC Air Conditioner, continued
2.3 Temperature Control Board
The temperature control board monitors the compressor, condenser fan, and alarm control.
Its remote temperature sensors monitor compressor discharge and evaporator suction line
temperature. A board-mounted temperature sensor monitors enclosure temperature. An
optional remote temperature sensor can monitor a specific area in the enclosure. The board
incorporates a low-voltage shutdown fixed at 42V for the 48VDC air conditioner, and 21V for
the 24VDC air conditioner.
A temperature sensor on the discharge line of the compressor regulates the condenser fans.
At low outdoor ambient temperatures, the condenser fans cycle on or off to maintain pressure
across the expansion valve.
A temperature sensor on the suction line exiting the evaporator monitors low evaporator
temperature, which can result from blocked evaporator air flow or faulty evaporator fans. This
condition sends out a minor alarm and shuts down the compressor until the suction lines
warm up again.
Fig. 2-2, Temperature Control Board
704-71-
Temperature
Set Point Jumper
Local-Remote Temp
Sensor Jumper
Enclosure Over
Temp Jumper
Minor Alarm LED and
N/C - N/O Jumper
Major Alarm LED and
N/C - N/O Jumper
Under Temp
Shutdown Jumper
DC Power
Input
DC Aux
Output
Major/Minor
Alarm Output
Remote Enclosure
Temp Probe
+ - + -