Impulse DO4837R - Manual (Page 23)

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CPC® CONTROLLER - OVERVIEW
Controller Overview
The CPC® ESC3 series is an electronic refrigeration controller that provides control of compressor,
fan and defrost management. The ESC3 provides control of a compressor (or solenoid) valve in re-
sponse to temperature variations.
Temperature Control
Temperature control in the ESC3 is accomplished by comparing the temperature reading of the case
temperature probe against the temperature set point. The compressor output is used to control the
temperature. If the temperature is above the temperature set point (LI) + the hysteresis set point (rd),
the compressor output is turned on. If the temperature is below the temperature set point - the hys-
teresis set point, the compressor output is turned off.
Compressor Control
Several setpoints are available that allow the operation of the compressor output to be tailored to
match individual needs.
Min ON/Off Times and Minimum Cycle Time
Minimum ON/OFF compressor times can be specified, as well as a minimum time delay between
compressor cycles. These parameters help prevent short cycling.
Compressor Power On Delay
Compressor power on delay setpoint (c0) allows the user to specify a delay after the power-up of the
controller. The compressor output will not come on regardless of the temperature reading until this
amount of time has expired.
Compressor Safety Cycle
The Compressor Safety Cycle setpoint (c4) specifies a cycle time that the compressor is to be cycled
if the temperature sensor used for control fails. If this setpoint is 0, the compressor will be off. If this
setpoint is 100, the compressor will be on. Any value between 1 and 99 will result in the compressor
being on for that period of time. At the end of this time, the compressor will be shut off for approxi-
mately 15 minutes.