Specifications

Operation
Operator Responsibilities
It is important that the operator become familiar with the equipment and the system before attempting to operate
the chiller.
During the initial startup of the chiller, the McQuay technician will be available to answer any questions and
instruct in the proper operating procedures.
It is recommended that the operator maintain an operating log for each individual chiller unit. In addition, a
separate maintenance log should be kept of the periodic maintenance and servicing activities.
Now that you have made an investment in modern, efficient McQuay equipment, its care and operation should
be a high priority. For training information on all McQuay HVAC products, please visit us at www.mcquay.com
and click on Training, or phone [phone] and ask for the Training Department. These sessions are
structured to provide basic classroom instruction and include hands-on operating and troubleshooting exercises.
Compressor Operation
The WMC compressors are two-stage. Suction gas enters the compressor through inlet guide vanes that can be
opened and closed to control refrigerant flow as the cooling load changes. The suction gas enters the first stage
impeller, is compressed, and travels through the vaned radial diffuser to the second stage impeller where
compression is completed. The gas travels to the condenser via the discharge volute, which converts any
remaining velocity pressure to static pressure.
Motor cooling is accomplished by utilizing the refrigerant effect of high-pressure liquid refrigerant from the
condenser expanded to a gas within the compressor. The refrigerant cools VFD heat sinks and the motor.
A five-axis magnetic bearing system supports the motor/compressor shaft, resisting radial and thrust forces. The
bearing control system uses shaft position feedback to continually adjust the bearing to keep the shaft in the
correct position. In the event of a power failure, the compressor motor acts as a generator and powers the
bearing support system during coastdown. There is also a system to gently de-levitate the shaft.
Many controls are mounted directly on the compressor where they monitor and control compressor operation.
These compressor controls are interfaced with the conventional MicroTech II controls to provide a complete
chiller control system.
Operating Limits:
Maximum standby ambient temperature, 130°F (55°C)
Minimum operating ambient temperature (standard), 35°F (2°C)
Leaving chilled water range, 38°F to 60°F (3°C to 15°C)
Maximum operating evaporator inlet fluid temperature, 66°F (19°C)
Maximum startup evaporator inlet fluid temperature, 90°F (32°C)
Maximum non-operating inlet fluid temperature, 100°F (38°C)
Minimum condenser water entering temperature (with condenser bypass), 55°F (12.8°C)
Maximum entering condenser water temperature, 105°F (40.6°C)
Maximum leaving condenser water temperature, 115°F (46.1°C)