Freeze-Up Protection; Compressor Management - Elstat ems55advanced Manual

ems controllers can also switch on an external heating element for the duration of the defrost cycle if the evaporator off-
cycle alone is not sufficient to defrost the evaporator. The option to use an external heating element is set with the heating
element defrost (dHr) and is primarily used with sub-zero coolers.
To help place the evaporator sensor, calibration 2 (C A2) can add an offset to evaporator sensor temperatures. Failures of
the evaporator sensor result in the PF3 alarms. For PF3 alarms, ems controllers continue to run the compressor normal
and alternate the display PF3 and the appliance sensor temperature.
5.7

freeze-up protection

Freeze-up protection prevents over cooling.
Freeze-up protection occurs if the temperature measured on the appliance sensor falls below the freeze-up protection
(dtt) temperature.
During freeze-up protection, ems controllers display 888 and stop the compressor to prevent further cooling.
ems controllers then resume normal operation when the temperature rises to the freeze-up protection (dtt) temperature
plus the differential (dI F) temperature.
For ems controllers that manage the evaporator fan, the ems controller starts the evaporator fan cycle.
For more information about the parameters used in freeze-up protect:
See "differential (dIF)" on page 72
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See "freeze-up protection (dtt)" on page 74
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5.8

compressor management

ems controllers manage the compressor to maintain the product temperature between the set point (S P) temperature and
the set point (S P) plus differential (dI F) temperature in the ready mode or between the saving set point (S S P) temperature
and the saving set point (S S P) plus the saving differential (S d) temperature in the saving mode.
To ensure that the pressures within the refrigeration system have time to equalize during compressor off-cycles, the com-
pressor rest time (rt) defines the minimum time that the compressor can be switched off.
Compressor manufacturers usually recommend a minimum compressor rest time.
The compressor rest time (rt) helps to avoid the following:
passing peak current through the windings of the compressor motor
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switching off the refrigeration system on the thermal overload protection
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short-cycling the refrigeration system.
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