RTAA-SVX01A-EN 99
Controls Interface
Low Refrigerant Temperature Cutout and Low Pressure Cutout Retry
If the LRTC or LPC trips despite the low ambient temperature start logic, the
circuit will be permitted to shutdown and retry one time.
If the LRTC or LPC trips within the first 20 minutes after initial start but after
the low ambient ignore time (grace period), the compressor stops immedi-
ately and the Restart Inhibit timer is set to one minute. After time expires, the
compressor will reset if there is a call for cooling.
If the LRTC or LPC trips again during the grace period, a CMR diagnostic will
occur. If there is an LRTC or LPC trip anytime after the grace period, a CMR
diagnostic will occur.
Balanced Compressor Starts and Hours
This feature is enabled/disabled in Balanced Starts and Hours (Service
Settings Menu). When enabled, the UCM will start the compressor with the
fewest starts and stop the compressor with the greatest hours, as deter-
mined by the “Compressor Starts” accumulator and the “Compressor
Hours” accumulator. This will tend to balance out hours and starts equally
over both compressors.
Phase Imbalance Protection
The Clear Language Display monitors the current in each phase and calcu-
lates the percentage of imbalance as follows:
Figure 36 Low Refrigerant Temperature and Low Pressure Cutout Ignore Time
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7
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3
&
,
J
Q
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7
L
P
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% Imbalance
l
x
l
ave
–()x 100
l
ave
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