Product manual

KPMWC00905-10EN - page 6/24
Magnetic bearing system
Fig.4 Fig.5
Fig.6
1. The rotor shaft’s position is held by front and rear electro-magnetic cushions;
2. The shafts position is monitored with 10 sensors that send a signal to a digital controller which then sends a
command to the 5 separate pulse width modulators (PWM), for a proper shaft repositioning;
3. In case of power failure, within 0.5 micro-seconds, the motor acts as a generator for the magnetic bearings and
the compressor comes gradually to a complete stop; the rotor de-levitates normally unto backup bearings.
Onboard capacitors have enough power to fully support the bearing system during the coast down.
The friction losses and the oil management hardware and controls associated with conventional oil-lubricated bearings
are now totally eliminated.
There is no need for oil pumps, oil reservoirs, controls, starter, piping, heaters, oil coolers, oil filters, water regulating
valves or oil relief valves that are needed to maintain oil quality. These devices can be a source of problems in traditional
chillers, and removing them significantly increases unit reliability and reduces the maintenance.
Modern magnetic bearing technology along with the integrated VFD (variable-speed drive) enables outstanding energy
efficiency, especially at partial loads, where significant gains can be realized.
The improvements in terms of efficiency and annual energy cost is maximised when there are long periods of part load
operation.
Also the inrush current is strongly reduced thanks to the use of VFD, resulting in an advantageous down-sizing of
electrical protection devices.