Specifications

The Compressor Technology
Variable Frequency Drives
Compressor unloading and subsequent chiller
capacity reduction is accomplished by a
compressor-mounted variable frequency drive. It
operates in conjunction with the inlet guide vanes.
The VFDs are an important factor in providing the
tremendous energy savings at part load operation.
The advanced, magnetic bearing, permanent magnet
synchronous motor technology used in the WMC
chillers offers many owner benefits.
Totally Oil-Free Operation
The friction losses and the oil management hardware
and controls associated with conventional oil-
lubricated bearings are now totally eliminated. Modern
magnetic bearing technology enables outstanding
energy efficiency and reliable, long-life frictionless
operation. The compressor’s one moving part (rotor
shaft and impellers) is levitated during rotation by a
digitally controlled magnetic bearing system consisting
of two radial and one axial magnetic bearing. Position
sensors at each magnetic bearing provide real-time
feedback to the bearing control system.
VFD
Figure 2, Cutaway of Magnetic Bearing Compressor
Reduced Installation Costs
1
1
.
.
Magnetic Bearings and
Bearing Sensors
Compact Design Facilitates Retrofits
78.0
(1981.2)
35.0
(889.0)
4.0
(101.6)
26.5
(673.1)
8.0”
. 2 QTY
Model WMC 150 fits through a 36-inch door.
Models 145, 250, and 300 fit through a 48-inch
door. This compact design allows installers to
easily move a WMC into an equipment room
through most existing doors. This feature saves the
cost of removing walls
and expanding
doorways to maneuver
the unit into its final
location.
2
2
.
.
Permanent Magnet
Synchronous Motor
3
3
.
.
Touchdown Bearings
4
4
.
.
Shaft and Impellers
5
5
.
.
Compressor Cooling
Variable Frequency Drives = Ultra-Low IPLV
The well-proven energy performance advantages of
large central plant type variable-speed centrifugal
chiller compressors now benefit mainstream, middle-
market applications through the use of high-speed,
centrifugal compression with integral variable-speed
drive. The compressor speed reduces as the condensing
temperature and/or cooling load reduces, optimizing
energy performance through the entire operating range.
Movable inlet guide vanes redirect gas flow into the
first stage impeller during very low loads, after the
compressor has reached minimum speed.
In particularly tight
rigging situations, the
unit can be shipped
knocked-down to save
disassembly cost at the
job site.
6.
QTY
0”
. 2
Out
In
Figure 1, End View of
WMC Chiller
Ultra-Smart
Line Reactor Included; Harmonic Filter
and EMI Filter Optional
The chillers utilize digital control electronics to
proactively manage unit operation, while providing
control of external circulating pumps and the cooling
tower. Web-enabled monitoring accesses a full array of
performance and reliability information.
Each compressor has a line reactor mounted in the
compressor’s power panel and included as
standard equipment. See page
38 for more
information.
6 Catalog WMC-4