Johnson Controls YORK YVAM 0350, Operation & Maintenance Manual

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Table 92: Safety shutdown messages
Message Description
CONTROL PANEL –
LOSS OF CONTROL
VOLTAGE
The line power input signal at I/O board TB3-81 was low for 1 second continuous. This signal is used
to determine when the digital inputs are affected by a line power loss versus an actual condition
for their devices. This fault is not expected on an actual loss of microboard power from the critical
load bus, because the processor shuts off before the fault delay. This message can indicate a Cycling
(auto-restart after power failure) or Safety (manual restart after power failure) shutdown, depending
on the control center configuration.
CONTROL PANEL –
POWER FAILURE
A Control Power failure has occurred. If the power failure occurred while the chiller was running, it
automatically restarts when power is restored. This message can indicate a Cycling (auto-restart after
power failure) or Safety (manual restart after power failure) shutdown, depending on the control
center configuration. It indicates a cycling shutdown when displayed in orange characters and a
safety shutdown when displayed in red characters. The control center is configured for auto-restart
or manual restart after power failure by a qualified service technician following instructions in YORK
YVAM Service Manual (Form 160.88-M2) .
DISCHARGE – HIGH
TEMPERATURE
The discharge temperature, as detected by the Discharge Temperature Thermistor, has increased to
greater than 220.0°F (104°C). The chiller can be started after the temperature decreases to less than
220.0°F (104°C) and the Clear Fault button is pressed.
DISCHARGE – LOW
TEMPERATURE
The discharge temperature, as detected by the Discharge Temperature Thermistor, has decreased
to less than 30.0°F (-1.1°C). The chiller can be started after the temperature increases to greater than
30.0°F (-1.1°C) and the Clear Fault button is pressed.
EVAPORATOR – LOW
PRESSURE
The evaporator pressure, as detected by the Evaporator Transducer, has decreased to the shutdown
threshold and caused cycling shutdown three times in a 90 minute period. For water cooling
applications, the shutdown threshold is a fixed value. For brine cooling applications, the shutdown
threshold varies according to the concentration of the brine solution. The brine shutdown threshold
is programmed at the YORK Factory. It must not be changed by anyone other than a qualified service
technician following instructions in YORK YVAM Service Manual (Form 160.88-M2) .
Application Shutdown (psig) Restart (psig)
Water cooling 25.0 25.1
Brine cooling 6.0 to 25.0 as programmed +0.1> Shutdown threshold
The chiller can be started after the evaporator pressure increases to the restart threshold and the
Clear Fault button is pressed.
EVAPORATOR – LOW
PRESSURE – SMART
FREEZE
Smart Freeze protection is activated and has shut down 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
YORK YVAM Service Manual (Form 160.88-M2) , this parameter is used as the evaporator refrigerant
temperature and the freeze threshold is 32.8°F (0.4°C). 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 (1.1°C).
The total count is incremented once for every second the evaporator refrigerant temperature is
below the freeze threshold, but it is never decremented below zero. The number of seconds it takes
the chilled liquid to freeze is based on how far the evaporator refrigerant temperature is below the
freeze threshold as follows:
# seconds to freezing = (4053.7) / (freeze threshold – evap. refrigerant temp.)
Smart Freeze is activated only if the feature has been Enabled by a service technician, following
instructions in YORK YVAM Service Manual (Form 160.88-M2) , and the Leaving Chilled Liquid
temperature Setpoint is less than 38.0°F (3.3°C).
YVAM Control Center 102