McQuay WGS190AW User Manual

OM WGS-5 WGS 130A to 190A 63
 EXV State has been Preopen for a time greater than the preopen timer set point
T3 – Transition from Pressure Control to Superheat Control
Requires all of the following
 Suction Superheat > Superheat target
 Evap LWT <= 60 F
 EXV State = Pressure AND Discharge Superheat >= 22 F for at least 3 minutes
T4 – Transition from Superheat Control to Pressure Control
Requires any of the following
 Evap LWT > 63 F
 Low Evap Pressure Unload event active
 Discharge Superheat < 22 F or > 40 F
T5 – Transition from Pre-open to Closed state
 Compressor State = Off and unit configured for remote air-cooled condenser and EXV
post open timer (non-field-adjustable at 30 seconds) has expired.
 Compressor State not Run
T6, T7 – Transition from any state to Closed state
Requires the following
 Compressor State not Run
EXV State Transitions – Aircooled
The following state diagram shows the transitions between EXV control states for remote
air-cooled
operation when evaporator pressure is greater than condenser pressure at start.
Power ON
Closed
Superheat
Pressure
EXV States
T1T4T5
T2
T3
Transitions:
T1 – Transition from Closed to Pressure Control
Requires all of the following
 Unit State = Auto
 Evap State = Run
 Compressor is available
 Compressor is next on
 Stage up now flag is set
 Compressor State = Off
T2 – Transition from Pressure Control to Superheat Control
Requires all of the following
 Suction Superheat >= Superheat target
 Evap LWT <= 60F

McQuay WGS190AW Specifications

General

Brand	McQuay
Model	WGS190AW
Category	Chiller
Language	English