York YK Style H Operation Manual page 180

SECTION 3 - DISPLAY MESSAGES
Center – Service Instructions (Form 160.76-M1). The
chiller can be started after the Evaporator Pressure in-
creases to the restart threshold and the Clear Fault key
is pressed on the display.
Water Cooling - R22
- R134a
Brine Cooling - R22
as programmed
- R134a
as programmed
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 Refrig-
erant Temperature sensor RT7 is enabled, (using pro-
cedure in OptiView Control Center – Service Instruc-
tions (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 Evapo-
rator 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:
number of seconds
=
to freezing
freeze threshold – evap.
Smart Freeze is activated only if the feature has been
enabled by a Service Technician (following instruc-
tions in OptiView Control Center – Service Instruc-
tions (Form 160.76-M1)) and the Leaving Chilled Liq-
uid Temperature Setpoint is less than 38.0°F.
180
SHUTDOWN RESTART
(PSIG) (PSIG)
54.3 54.4
25.0 25.1
+0.1 more
25.0 to 54.3 than
Shutdown
threshold
+0.1 more
than
6.0 to 25.0
Shutdown
threshold
(4053.7)
refrigerant temp.
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 Evapo-
rator Pressure to a Saturated Temperature value and
compares this value to the Leaving Chilled Liquid tem-
perature (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 continu-
ously for 10 minutes. For Steam Turbine drive appli-
cations, 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 in-
structions in OptiView Control Center – Service
Instructions (Form 160.76.M1)
• Not in Brine Cooling mode
• Smart Freeze is enabled
• Evaporator Temperature Sensor (RT7) or Evapo-
rator Saturation Temperature is indicating a tem-
perature 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.
FORM 160.76-O2
issue date: 6/15/2015
JOHNsON CONtROLs