Communications: electrical – Condition responsive indicating system – Specific condition
Utility Patent
1998-10-07
2001-01-02
Wu, Daniel J. (Department: 2736)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S635000, C340S679000, C324S127000
Utility Patent
active
06169489
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to the field of detecting motor conditions, and more particularly to detecting motor contamination conditions.
BACKGROUND OF THE INVENTION
When dust or other contaminants—especially combined with high humidity—build up on the windings of high voltage machines, the electric field distributions may be distorted to the point of breakdown between sections of the winding or connections at different voltages. With downsized maintenance organizations, cleaning of the windings is often neglected, leading to problems of this nature.
Ground fault detectors are often employed to trip a machine when significant current flows to ground due to actual insulation failure. Otherwise PDA (Partial Discharge Analysis) may be used to detect the presence of contamination, but very special (and usually expensive) instrumentation is needed.
It would be desirable to provide a low cost, on-line, continuous monitor that can be integrated into normal motor protection relays that will warn of dangerous levels of contamination so that action may be taken to clean the windings as needed.
SUMMARY OF THE INVENTION
The invention herein disclosed relates to a motor winding contamination detector which includes a current transformer comprising a magnetic core and a sensing coil wound about the magnetic core. The motor phase leads pass through a window of the core. The detector also includes processing means to process a sub-trip level current from the sensing coil to detect at least one of: a trend contamination signature, a leakage contamination signature, and a clustering contamination signature. An alarm is generated when predetermined alarm generation criteria have been met, the alarm generation criteria being functions of at least one of the contamination signatures. The zero sequence current is used as an indicator of currents flowing to ground as a result of contamination of the windings
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Kliman Gerald Burt
Rehder Robert Henry
General Electric Company
Snyder Marvin
Stoner Douglas E.
Trieu Van T.
Wu Daniel J.
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