York YK Style H Operation Manual page 173

-OR-
• The chiller has been shut down for greater than 30 minutes and the oil temperature minus
the condenser saturation temperature is less than 40°F.
-OR-
• Following a power failure, upon restoration of power, the oil temperature minus the
condenser saturation temperature is less than 40°F.
Oil – Low Temperature
The oil temperature has decreased to less than 55°F. The chiller will automatically restart when
the temperature increases to greater than 55.0°F and is greater than the Condenser Saturated
temperature by 30 or 40°F, as described above in the Oil – Low Temperature Differential message
description.
Control Panel – Power Failure
A Control Power failure has occurred. If the power failure occurred while the chiller was running, it
will automatically restart when power is restored. However, if the power failure duration was less
than the duration of the applicable coastdown period (2.5 minutes standard; 15 minutes steam
turbine) when power is restored, the remainder of the coastdown will be performed, prior to the
chiller starting. This message can indicate a Cycling (auto-restart after power failure) or Safety
(manual restart after power failure) shutdown, depending upon Control Center configuration.
It indicates a cycling shutdown when displayed in orange characters; 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 OptiView Control Center - Service Instructions (Form
160.76-M1).
Leaving Chilled Liquid – Low Temperature
The Leaving Chilled Liquid Temperature has decreased to the programmed Shutdown Temperature
Setpoint. If the chiller is running when this occurs, the Pre-rotation Vanes are driven fully closed
prior to shutting down the chiller. The chiller will automatically restart when the temperature
increases to the programmed Restart Temperature Setpoint.
If the chiller is operating in Heat Pump Heating mode, (Heat Pump Duty is enabled, and the Heat
Pump Operational mode setpoint is set to Heating), there is additional logic that will cause this
Shutdown when the Leaving Chilled Liquid Temperature (LCHLT) decreases below the programmed
Heating LCHLT Shutdown Temperature Setpoint. For details of this setpoint, see the
screen.
Leaving Condenser Liquid – High Temperature
The Leaving Condenser Liquid Temperature has increased to the programmed Leaving Condenser
Liquid Temperature Cycling Offset - Shutdown Setpoint. This shutdown is only applicable to Heat
Pump Duty enabled and operating in Heating mode (Heat Pump Operational Setpoint set to
Heating mode). See the
Anytime the Leaving Condenser Liquid Temperature Setpoint is decreased, the shutdown threshold
becomes 125°F for the next 10 minutes. After 10 minutes have elapsed, the shutdown threshold
becomes the programmed setpoint value. The Heat Pump will automatically restart when the
temperature decreases to the programmed Leaving Condenser Liquid Temperature Cycling offset –
Restart Setpoint.
Model YK Style H Centrifugal Liquid Chillers with OptiView Control Center
Heat pump screen.
Heat pump
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