YZ Engineering Guide
Form: 161.01-EG1 (0618)
9
VARIABLE SPEED DRIVE
Note
: Please refer to the YZOperations & Maintenance Manual (161.01-OM1) for a complete description of features and
functionality.
A variable speed drive is factory-packaged and mounted on the YZ chiller. It is designed to vary the compressor motor
speed by controlling the frequency and voltage of the electrical power to the motor. The capacity control logic shall
automatically adjust motor speed and compressor diffuser geometry for maximum part load efficiency by analyzing
information fed to it by sensors located throughout the chiller. The variable speed drive is mounted in a NEMA-1/IP22
enclosure with all power and control wiring between the drive and chiller factory-installed. The chiller uses a single-point
power connection with a circuit breaker disconnect. Electrical lugs for incoming power wiring are provided.