Wizard Single Compressor Control System

- a large, multiple stage reciprocating compressor

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Features

The Wizard Single Compressor Control is designed to operate a large, multiple cylinder reciprocating compressor utilizing ammonia and most halocarbon refrigerants.

Suction Pressure Control

The WSCC will maintain the suction pressure as close as the Suction Pressure Setpoint by turning on/off the compressor and the unloaders.

The WSCC will initially start the compressor in the fully unloaded (lowest capacity) configurations. Should additional capacity be required, the WSCC, after a calculated delay, will turn off (add capacity) the next available unloader. Each unloader will be staged sequentially, in a First On-Last Off (FILO) sequence.

Once the suction pressure drops below the suction pressure setpoint, the WSCC will turn on Unloader stages, thus reducing the compressor capacity until the compressor is fully unloaded. Only then, should the pressure continue to be lower than the setpoint, will the WSCC shut off the compressor.

The compressor will not be restarted until after a user configurable compressor restart delay expires. Restart of the compressor will consist of the compressor fully unloaded.

Condenser Control

The WSCC operates a single condenser circuit based upon a fixed head pressure setpoint. The WSCC activates this control scheme whenever the compressor is running.

The WSCC will start the condenser when the head pressure exceeds the setpoint by three percent of the setpoint value (ie. Setpoint = 200 psi, Condenser start value = 206 PSI). The WSCC will shut off the condenser when the head pressure drops below the setpoint by 1.5 percent of the setpoint.

The condenser operates on a 30 sec minimum runtime and off time delay.

Compressor Cylinder Cooling

The WSCC monitors the temperature of the compressor head, cycling a relay to start head cooling should the temperature exceed a user configurable setpoint. This relay can be used for a head fan, liquid injection, or a water cooling system.

Monitoring and Alarming

The WSCC monitors six separate sensors and activates alarms based upon user definable alarm setpoints. These alarms include:

Low Suction Pressure - The WSCC will shutdown all compressor operations and activate alarms when the suction pressure is below the Low Suction Alarm Setpoint for a user defined delay period

High Suction Pressure - The WSCC will shutdown all compressor operations and activate alarms when the suction pressure exceeds the High Suction Alarm Setpoint for a user defined delay period

Low Oil Pressure Differential - The WSCC monitors an oil pressure transducer and calculates the pressure differential. The WSCC will shutdown the compressor operation and activate an alarm when the oil pressure differential is below the Low Oil Pressure Differential Alarm Setpoint for a user defined delay period

High Head Pressure - The WSCC monitors the Head/Discharge Pressure Transducer and will shutdown the compressor operation and activate an alarm when the head pressure exceeds the High Head Pressure Alarm Setpoint for a user defined delay period

Low Head Pressure - The WSCC monitors the Head/Discharge Pressure Transducer and activates an alarm when the head pressure is below the Low Head Pressure Alarm Setpoint for a user defined delay period

High Discharge Temperature - The WSCC monitors a high temperature sensor mounted to the discharge manifold. The WSCC activates an alarm when the discharge temperature exceeds the High Discharge Temperature Alarm Setpoint for a user defined delay period

Low Discharge Temperature - The WSCC monitors a high temperature sensor mounted to the discharge manifold. The WSCC activates an alarm when the discharge temperature goes below the Low Discharge Temperature Alarm Setpoint for a user defined delay period

High Oil Temperature - The WSCC monitors a high temperature sensor measuring the oil chamber of the compressor. The WSCC activates an alarm when the discharge temperature exceeds the High Oil Temperature Alarm Setpoint for a user defined delay period

Low Oil Temperature - The WSCC monitors a high temperature sensor measuring the oil chamber of the compressor. The WSCC activates an alarm when the discharge temperature goes below the Low Oil Temperature Alarm Setpoint for a user defined delay period

High Head Temperature - The WSCC monitors a high temperature sensor mounted to the discharge manifold. The WSCC activates an alarm when the discharge temperature exceeds the High HeadTemperature Alarm Setpoint for a user defined delay period

Low Head Temperature - The WSCC monitors a high temperature sensor mounted to the discharge manifold. The WSCC activates an alarm when the discharge temperature goes below the Low Head Temperature Alarm Setpoint for a user defined delay period

System Standby

The WSCC can be utilized as a sub-controller for a larger refrigeration control system. A close signal to the STANDBY input will shut down all compressor operations. The system will remain in this standby mode until the input receives an open signal.