Machine Protection
and Adaptive
Control
High Vacuum Lockout
The oil sump pressure is below the lockout setpoint. Starting of compressor is inhibited as a result.
Low Oil Temperature Start Inhibit The oil temperature is at or below the low oil temperature start inhibit setpoint (143°F/61.7°C). The heater is energized to raise the oil temperature.
Low oil temperature is indicative of refrigerant dilution in the oil. Oil temperature is used to estimate this dilution since the oil temperature directly corresponds to amount of refrigeration dilution in the oil. It is required that oil contains minimal refrigerant in it. This is accomplished by boiling the refrigerant out of the oil by maintaining a high enough oil temperature.
If the oil temperature is at or below a given Low Oil Temperature Inhibit setting (default 95°F/35°C) the compressor cannot be started. This is an inhibit mode and will be reported to the operator interface. The oil heater is energized in an attempt to raise the oil temperature over this inhibit temperature setpoint. The compressor is inhibited from starting until the oil temperature is raised 5 or more degrees above this setpoint.
The Low Oil Temperature Start Inhibit is tested on every start unless a quick restart is being performed during post lube.
If the Enhanced Oil Temperature Protection setting is enabled, the Low Oil Temperature Start Inhibit value is the greater of 100°F/37.8°C or the Saturated Evaporator Refrigerant Temperature + 30°F/16.7°C.
If the Enhanced Oil Temperature Protection setting is not enabled, the Low Oil Temperature Start Inhibit value is settable with the Low Oil Temperature Start Inhibit Setpoint via the service tool.
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