SPX Cooling Technologies TG MAG185-125 Water Pump User Manual


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A.0500.551 – IM-TGMAG/02.00 EN (02/2008)
3.16 Components of the magnetic drive
3.16.1 Magnetic coupling
The magnetic coupling is transmitting the torque of the drive motor to the rotor shaft.
Themagneticcouplingarrangementreplacesadynamicshaftsealandmakesthepump100%
leakfree.
The magnetic coupling consists of following components:
The outer magnetic rotor is assembled on the pump shaft which is driven by the motor. The inner
magnetic rotor is mounted on the rotorshaft inside the wet part of the pump. The separation can is
situated between the outer and inner magnetic rotor and is sealing the pump hermetically.
Permanent magnets are mounted on the inner and outer rotor of the magnetic coupling. The magnets
on the inner magnetic rotor are completely encapsulated in stainless steel to prevent contact with the
pumped medium. The magnets mounted on the outer rotor are open and protected against corrosion
in contact with the atmosphere. The torque is transmitted by magnetic fields between inner and outer
magnets which are passing through the stationary separation can. Inner and outer magnetic rotor are
running synchronically without slip.
The separation can is a welded construction where the flange and bottom plate are welded to
the thin walled pipe section. The can is designed for system pressures up to 25 bar. The section
between the magnetic rotors is made of Hastelloy in order to minimize eddy current losses. The
separation can is sealed against the intermediate cover by an O-ring.
When the torque of the pump exceeds the maximum allowable torque of the magnetic coupling,
the coupling slips. The slipping of the coupling is associated with excessive heat generation and
strong vibrations, which can damage the coupling permanently and destroy the bearings. Therefore
the drive motor must be switched off as soon as the coupling slips due to overload. This situation
can be detected by following means
• Dropinowoutput
• Dropofdischargepressure
• Reducedpowerconsumptionofthedrivemotor
The drive motor must be stopped in order to stop the slipping of the magnetic coupling.
Outer magnetic rotor
Separation can
Inner magnetic rotor
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