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MICROPROCESSOR CONTROL SYSTEM
Each condensing unit are provided with microprocessor based control board that monitors analog and digital inputs to
achieve precise control and safety functions during unit’s operation. Input signals for cooling control can be digital signals
coming from a thermostat device or analog signals from a PTC temperature sensor. The push button key board allows
accessing to the operating conditions, control set points (in case temperature control is analog signal), & alarm history
that are clearly displayed on a multi-line back illuminated LCD panel.
The unit’s controller consists of the following hardware:
1. User Interface Board – Includes push buttons to access operating conditions, change control set points, and
view alarm history. Data are clearly displayed on its LCD panel.
2. Main Board – This controls up to 2 compressor system.
3. Auxiliary Boards – Required for controlling an additional (2) or more compressors.
LCD Display Information:
In the normal operating mode, the 20 x 4 characters LCD panel displays the system status, temperature of leaving /
returning air and set point (if temperature control selected is through PTC sensors ), run time of compressor and alarm
history.
Measurement data for each circuit can be easily accessed and displayed on the LCD. Data include the following:
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Suction, Discharge, and Oil pressures
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Leaving / Returning Air temperature ( if temperature control selected is through PTC sensors )
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Compressor Motor Status
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Condenser Fan Motor Status
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Liquid Line Solenoid Status
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Supply Fan Motor Status
There are three LED lights on the user interface board to indicate “Power On” (green), “Menu Adjustment” (yellow) and
“Fault” (red).
SYSTEM PROTECTION
The unit is equipped with protective devices against motor overloads and proper system settings are factory set to ensure
safe and reliable operation of the unit. Some of these devices and settings are as follows:
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Compressor Motor External Overload Relay
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Compressor Motor Winding Over Temperature Protection
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Low suction Pressure
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High Discharge Pressure
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Low Oil Pressure
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Compressor Anti-Recycling Timer