McQuay WGS190AW User Manual

38 WGS 130A to 190A OM WGS-5
No Pressure Change At Start
Alarm description (as shown on screen): NoPressChgAtStart N
Trigger: After start of compressor, at least a 1 psi drop in evaporator pressure or 5 psi rise
in discharge pressure has not occurred after 15 seconds.
Action Taken: Rapid stop circuit
Reset: This alarm can be cleared manually via the Unit Controller keypad.
Circuit Events
The following events limit operation of the circuit in some way as described in the Action
Taken column. The occurrence of a circuit event only affects the circuit on which it
occurred. Circuit events
are logged in the event log on the unit controller.
Low Evaporator Pressure - Hold
Event description (as shown on screen): EvapPress Low Hold N
trigger: The low pressure events are not enabled until the compressor has started and the
evaporator pressure has risen above the Low Evaporator Pressure - Hold set point. The unit
mode must also be Cool. Then, while running, if evaporator pressure <= Low Evaporator
Pressure - Hold set point the event is triggered.
Action Taken: Inhibit loading by only allowing the slide target to be reduced.
Reset: While still running, the event will be reset if evaporator pressure > (Low Evaporator
Pressure - Hold SP + 2psi). The event is also reset if the unit mode is switched to Ice, or the
compressor state is no longer Run.
Low Evaporator Pressure - Unload
Event description (as shown on screen): EvapPressLowUnload N
Trigger: The low pressure events are not enabled until the compressor has started and the
evaporator pressure has risen above the Low Evaporator Pressure - Hold set point. The unit
mode must also be Cool. Then, while running, if evaporator pressure <= Low Evaporator
Pressure - Unload set point the event is triggered.
Action Taken: Unload the compressor by decreasing the slide target 5% every five seconds
until the evaporator pressure rises above the Low Evaporator Pressure – Unload set point.
Reset: While still running, the event will be reset if evaporator pressure > (Low Evaporator
Pressure - Hold SP + 2psi). The event is also reset if the unit mode is switched to Ice, or the
compressor state is no longer Run.
High Lift Pressure - Hold
Event description (as shown on screen): LiftPressHigh Hold N
Trigger: While the compressor is running and unit mode is Cool, if saturated condenser
temperature >= High Saturated Condenser - Hold Value, the event is triggered.
Action Taken: Inhibit loading by only allowing the slide target to be reduced.
Reset: While still running, the event will be reset if saturated condenser temperature <
(High Saturated Condenser - Hold Value – 10
o
F). The event is also reset if the unit mode is
switched to Ice, or the compressor state is no longer Run.
High Lift Pressure - Unload
Event description (as shown on screen): LiftPressHighUnloadN
Trigger: While the compressor is running and unit mode is Cool, if saturated condenser
temperature >= High Saturated Condenser - Unload Value, the event is triggered.
Action Taken: Unload the compressor by decreasing the slide target 5% every five seconds
until the condenser pressure drops below the High Saturated Condenser - Unload Value.

McQuay WGS190AW Specifications

General

Brand	McQuay
Model	WGS190AW
Category	Chiller
Language	English