Harmonic Filter – DC Current Transformer 1
During initialization, with no current flowing through the DC Current Transformers (DCCT’s), the
DCCT output voltages are measured and compared with a preset limit via the Filter Logic Board. If
the measured values exceed the preset limits, the DCCT’s are presumed to be defective and this
shutdown is generated.
Harmonic Filter – DC Current Transformer 2
See
Harmonic Filter – DC Current Transformer 1
message.
Safety shutdown messages
Evaporator – Low Pressure
The Evaporator Pressure, as sensed by the Evaporator transducer, has decreased to the safety
shutdown threshold. For water cooling applications, the safety shutdown threshold is a fixed value
for the respective refrigerant. For Brine cooling applications, the safety shutdown threshold varies
according to the concentration of the Brine solution. The Brine shutdown threshold is programmed
at the YORK Factory. It should not be changed by anyone other than a qualified Service Technician
following instructions in
OptiView Control Center – Service Instructions (Form 160.76-M1)
. The chiller
can be started after the Evaporator Pressure increases to the restart threshold and the Clear Fault
key is pressed on the display.
Table 180: Shutdown and restart thresholds
Shutdown (PSIG)
Restart (PSIG)
Water Cooling - R-513A
29.0
29.1
Water Cooling- R-134a
25.0
25.1
Brine Cooling - R-513A
9.0 to 29.0 as programmed
+0.1 more than Shutdown threshold
Brine Cooling - R-134a
6.0 to 25.0 as programmed
+0.1 more than Shutdown threshold
Evaporator – Low Pressure - Smart Freeze
Smart Freeze protection is activated and has shutdown the chiller because the evaporator
temperature has been below the Smart Freeze threshold for greater than the allowable number
of seconds. If the Evaporator Refrigerant Temperature sensor RT7 is enabled, (using procedure
in
OptiView Control Center – Service Instructions (Form 160.76-M1)
), this parameter is used as the
Evaporator Refrigerant Temperature and the freeze threshold is 32.8°F. If RT7 is not enabled, the
Evaporator Refrigerant Temperature used is the Evaporator Saturation Temperature, derived from
the Evaporator Pressure transducer and the freeze threshold is 34.0°F.
The total count is incremented once for every second the Evaporator Refrigerant Temperature is
below the freeze threshold (but is never decremented below zero). The number of seconds it will
take the chilled liquid to freeze is based on how far the Evaporator Refrigerant Temperature is
below the freeze threshold as follows:
Smart Freeze is activated only if the feature has been enabled by a Service Technician (following
instructions in
OptiView Control Center – Service Instructions (Form 160.76-M1)
) and the Leaving
Chilled Liquid Temperature Setpoint is less than 38.0°F.
Model YK Style H Centrifugal Liquid Chillers with OptiView Control Center
184
