Pumps – Motor driven – Electric or magnetic motor
Reexamination Certificate
2011-04-12
2011-04-12
Kramer, Devon C (Department: 3746)
Pumps
Motor driven
Electric or magnetic motor
C417S423120, C417S423140, C310S06800R, C310S071000, C310S089000, C310S090000
Reexamination Certificate
active
07922467
ABSTRACT:
To protect the bearings, lubricant and seals of a refrigerant compressor, the compressor includes one or more inductors for mitigating a high frequency common mode current that produces a high frequency shaft voltage. Each inductor is a ring of magnetic material encircling three insulated cables that convey three-phase power from an adjustable frequency drive to the compressor's motor. Without the inductors, the high frequency shaft voltage can become damagingly high due to the length of a cast iron housing that can be particularly long if the housing contains both a motor and several centrifugal impellers. The high frequency shaft voltage is just one component of a composite adverse shaft voltage. Another component, known as an operationally induced shaft voltage, can be reduced by a grounding contact, so instead of using just an inductor or just a contact, both can be used to provide a total solution to the problem.
REFERENCES:
patent: 3122894 (1964-03-01), Bernhard
patent: 6987338 (2006-01-01), Lavasser et al.
patent: 2004/0056543 (2004-03-01), Melfi
patent: 2005/0174812 (2005-08-01), Wu
Duga Joel S.
Foye David M.
Swanson Robert M.
Kramer Devon C
O'Driscoll William
Stimpert Philip
Trane International Inc
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