JOHNSON CONTROLS
FORM 160.84-EG1 (617)
12
Equipment Overview
YORK YMC² Centrifugal Liquid Chillers are completely factory-packaged including the
evaporator, condenser, compressor, motor, VSD, control center, and all interconnecting
unit piping and wiring.
The initial charge of refrigerant is supplied for each chiller. Actual shipping procedures for
the chiller will depend on a number of project-specific details.
The services of a Johnson Controls factory-trained, field service representative are in-
curred to supervise or perform the final leak testing, charging, the initial start-up, and
concurrent operator instructions.
COMPRESSOR
The compressor is a single-stage centrifugal type directly driven by a hermetically-sealed,
permanent-magnet motor. A cast-aluminum, fully-shrouded impeller is mounted directly
to the motor shaft using a stretched tie-bolt. Impeller seals employ a labyrinth geometry,
sized to provide minimal thrust loading on the impeller throughout the operating range.
The impeller is dynamically balanced and overspeed tested for smooth, vibration-free
operation.
CAPACITY CONTROL
Capacity control will be achieved by the combined use of variable speed control and
mechanical flow regulation to provide fully modulating control from maximum to minimum
load. For normal air conditioning applications, the chiller can adjust capacity from 100%
to 15% of design. For each condition the capacity control devices will be automatically
adjusted to maintain a constant leaving chilled liquid tem perature at optimized efficiency,
based on information fed by sensors located throughout the chiller.
All mechanical actuators are external electrical devices which automatically and precisely
position components.
MOTOR
The compressor motor is a hermetically-sealed, high-speed design with a permanent
magnet rotor supported by active magnetic bearings. Each magnetic bearing cartridge
includes both radial and axial (thrust) bearings. The bearing controls provide a completely
oil-free operating system. The motor rotor and stator are cooled by a pressure driven re-
frigerant loop to maintain acceptable operating temperatures.
The active magnetic bearings are equipped with automatic vibration reduction and bal-
ancing systems to ensure smooth and reliable operation. In the event of a power failure,
the magnetic bearings will remain in operation throughout the compressor coast-down us-
ing a reserve energy supply. Mechanical bearings are included as backup to the magnetic
bearings and designed for emergency touchdown situations.
The active magnetic
bearings are equipped
with automatic
vibration reduc-
tion and balancing
systems
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