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6.2.5.3 Defrost
Use the Defrost tab to specify the conditions that cause defrosting to start and end.
Defrost Function
Define the defrost schedule timing interval or disable the defrost function. Selecting System Run Time specifies that the time interval between defrost (Time
to subsequent defrosts) is defined by the time that the controller is powered on and restarts if the controller is power cycled. Selecting Compressor Run
Time specifies that the defrost timing interval is defined as the accumulated time that the compressor is powered on and restarts if the controller is power
cycled. The defrost function can also be disabled.
NOTE: If you use Temperature Initiated Defrost, you must still select System Run Time or Compressor Run Time as a failsafe maximum time between
defrosting cycles.
Defrost Cycle at Power On
Select Enable to start a defrost cycle each time the controller is switched on or the appliance is power cycled in addition to the scheduled and temperature
initiated defrost cycles. Select Disable to only allow scheduled and temperature initiated defrosting.
Defrost Termination Temperature
Specifies the temperature that causes defrosting to end (and drip time to start – if drip time is defined). This is either the Control Sensor temperature or the
Evaporator Sensor temperature as chosen on the Configuration tab. This parameter is unavailable if the Defrost Function is disabled. If the defrost
termination method is based on the digital input Switch (NO) (set on the Configuration tab) this setting is disregarded by the controller.
WARNING: The controller terminates defrost when the digital input dry contacts close – Do not apply voltage.
Time to First Defrost
Specifies how long the controller waits before starting a defrosting cycle each time it is powered on. The timer that is used, System Run Time or Compressor
Run Time, is specified in Defrost Function. This parameter is unavailable if Defrost Cycle at Power On is enabled.
Time to Subsequent Defrosts
Specify how long the controller waits to start the second and subsequent defrost cycles after being powered on. The timer starts when the Drip Time timer
expires or, if drip time is not being used, when the defrost terminates either on failsafe time (Defrost Duration) or temperature (Defrost Termination
Temperature). A temperature initiated defrost cycle can occur before the Time to Subsequent Defrosts timer expires.
Type E7 EcoCool™ Electronic Temperature and Defrost Controllers
©2008 Invensys Controls All rights reserved.
DRAFT VERSION
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