Trane CVGF500 Installation, Operation & Maintenance Manual page 109

Restart Inhibit
This function provides short cycle protection for the motor, and indirectly also short
cycling protection for the starter since the starter is designed to operate the motor un-
der all the conditions of motor performance.
Restart Inhibit Function Using Time Base
This method uses straight start-to-start timer to determine when to allow the next
start. A Restart Inhibit Start-to-Start Time setpoint is used to set the desired start-to-
start time.
Default is 20 minutes and can be altered using the UT ™. A time based restart inhibit
function is used if the Restart Inhibit Type is set to 'Time' using UT ™ or if the motor
winding temperatures are determined to be invalid.
Note: When the start is inhibited by the restart inhibit function, the time remaining will
be displayed along with the restart inhibit mode. There is no 'free' start on a power up
of the UC800 since a real time clock is used to determine when the next start will be
allowed based on the start time of the previous start.
Low Oil Temperature Start Inhibit
When oil temperature is at or below the low oil temperature start inhibit setpoint
(80-140°F/26.7-60°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 refrigerant 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 enhanced oil temperature protection is disabled or below a given Low Oil Tempera-
ture Inhibit setting (default 95°F/35°C) the compressor cannot be started. This is an in-
hibit 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 tempera-
ture is raised 5°F (2.7°C) 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 136°F (57.8°C).
If the Enhanced Oil Temperature Protection setting is not enabled, the Low Oil Tem-
perature Start Inhibit value is settable with the Low Oil Temperature Start Inhibit Set-
point using the UT™.
Oil Temperature Control
The oil heater is used to maintain the oil temperature within +/- 2.5°F (1.4°C) of the oil
temperature control setpoint. The oil heater is commanded off when the oil pump is
commanded on.
If the oil temperature is at or below the Low Oil Temperature Cutout setpoint, this diag-
nostic will be issued and stops the compressor. This diagnostic is ignored for the first
CVGF-SVX03B-EN
Machine Protection and Adaptive Control
109