York YK Style H Operation Manual page 185

Evaporator – Transducer Or Leaving Liquid Probe
A possible defective Evaporator Pressure transducer or Leaving Chilled Liquid temperature
transmitter has been detected. The pressure and temperature that these devices are indicating
are not in the correct relationship to each other. The Control Center converts the Evaporator
Pressure to a Saturated Temperature value and compares this value to the Leaving Chilled Liquid
temperature (difference equals chilled liquid temp minus evaporator saturated temp). The
difference should not be outside the range of –2.5°F to +25.0°F.
If the transducer and transmitter are accurate, the Evaporator Saturated temperature should
not be greater than 2.5°F warmer nor greater than 25.0°F colder than the Leaving Chilled Liquid
Temperature. In order to initiate a shutdown, the difference must be outside the acceptable range
continuously for 10 minutes. For Steam Turbine drive applications, this check is bypassed for the
first 20 minutes of chiller operation. The chiller can be started after the Clear Fault key is pressed on
the display.
Evaporator – Transducer Or Temperature Sensor
A possible defective Evaporator Pressure transducer or Refrigerant Temperature Sensor has
been detected. The Control Center converts the Evaporator Pressure to a Saturated Temperature
value and compares this value to the optional Evaporator Refrigerant Temperature Sensor. If
the difference between these temperatures is greater than 3.0°F, continuously for 1 minute, this
shutdown is performed. This check is only performed under the following conditions:
• Chiller has been running for at least 10 minutes
• Evaporator Refrigerant Temperature (RT7) has been enabled by a Service Technician using
instructions in OptiView Control Center – Service Instructions (Form 160.76.M1)
• Not in Brine Cooling mode
• Smart Freeze is enabled
• Evaporator Temperature Sensor (RT7) or Evaporator Saturation Temperature is indicating a
temperature of less than 32.0°F
The chiller can be started after the temperatures are within 3.0°F of one another and the Clear Fault
key is pressed on the display.
Condenser – High Pressure Contacts Open
The contacts of the electromechanical high pressure safety switch have opened because this device
has detected a high pressure:
• More than 204 PSIG (R-134a)
The contacts will automatically close when the condenser pressure decreases to:
• Less than 160 PSIG (R-134a)
The chiller can be started after the contacts close and the Clear Fault key is pressed on the display.
Condenser – High Pressure
The condenser pressure, as sensed by the Condenser transducer, has increased to:
• More than 180.0 PSIG (R-134a)
The chiller can be started after the pressure decreases to:
• Less than 120.0 PSIG (R-134a) and the Clear Fault is pressed on the display.
Model YK Style H Centrifugal Liquid Chillers with OptiView Control Center 185