Trane R Series, Installation Operation & Maintenance

Page: 119 / 188

RLC-SVX07A-EN 119
Controls Interface
Phase Imbalance Protection
The Clear Language Display monitors the current in each phase and calcu-
lates the percentage of imbalance as follows:
= phase with greatest difference from lave (without regard to sign)
If Phase Unbalanced Protection (Service Settings Menu) is enabled, and the
average three phase current is greater than 80% RLA, and the percent of
imbalance is calculated to exceed 15%, the UCM will shutdown the
compressor and display a CMR diagnostic.
In addition to the 15% criteria, the Clear Language Display has a non-
defeatable 30% criteria which has its own diagnostic. If the 15% criteria is
enabled, it will always display the 15% diagnostic first. The 30% criteria is
always active when a compressor is running, regardless of% RLA.
Reverse Rotation Protection
The Clear Language Display monitors incoming current during start-up and
will shutdown the compressor within one second, if phase reversal is
detected.
CAUTION
Reversed Phase Rotation!
Phase relationships during installation of unit power must be
carefully controlled to assure compressor protection against
reversed phase rotation. See Installation - Electrical.
Oil Failure Protection
The 70 to 125 Ton units no longer use the differential pressure switch to
monitor for an oil line restriction. The logic of the UCM uses a comparison of
the entering oil temperature at the compressor to the saturated condenser
temperature to determine if there is an oil line restriction.
The differential between the entering oil temperature and the saturated
condenser temperature is referred to as the” Oil Loss Differential Setpoint” in
the Service Settings Menu. This setpoint must remain at the default of -4 F
for the unit to function properly.
If the entering oil temperature drops 4 F below the saturated condenser
temperature for more than 30 minutes, the circuit will shutdown on a CMR
diagnostic. The diagnostic will be presented as:
“OIL SYSTEM FAULT - CKT X°
% Imbalance
l
x
l
ave
–
( )
x 100
l
ave
-------------------------------------
=
l
ave
l
1
l
2
l
3
+ +
( )
3
------------------------------
=
1
x