Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – For fault location
Reexamination Certificate
1998-11-30
2001-10-09
Metjahic, Safet (Department: 2858)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
For fault location
C324S544000
Reexamination Certificate
active
06300767
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to the field of fault detection, and specifically to using certain emissions spectra from an insulated system to detect impending failure.
BACKGROUND OF THE INVENTION
Parallel plate busways for 600 volt (rms) systems often have high insulation failure rates when conditions are humid or wet. Most failures occur in joints between sections. A few occur in the sections between joints. Considerable damage to the loads and busway occurs when there is a failure, and down time is needed for repair. Presently, busway systems are tested off-line in an attempt to avoid sudden, unexpected, catastrophic failure. There is considerable expense and down time for periodic leakage resistance measurement (meggering) of the busway systems. Such insulation failures also occur in other types of insulated systems including transmission lines, switchgear equipment, motors, generators, transformers, capacitors, and inductors.
Partial discharge analysis is a common tool in monitoring high voltage motors and generators. Ultrasonic monitoring of exposed surfaces has been used to evaluate surface discharge conditions in motors and high voltage power lines. Chemical species detectors are widely used for safety monitoring. Additionally, as is well-known in the art, various kinds of apparatus commonly used in industry such as adjustable speed drives, and spot welders put energy into the same frequency range as the discharges that are being monitored. This can result in falsely predicting failure.
SUMMARY OF THE INVENTION
It is therefore desirable to provide a continuous on-line monitoring system for an insulated system to warn of impending failure.
To achieve this, a radio frequency (RF) or other form of detector is positioned at a selected location on the insulated system to detect discharges which can occur when electrical insulation becomes wet, for subsequent analysis and decision processes.
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Glaser John Stanley
Kliman Gerald Burt
Krahn John Raymond
Lester Howard LeRoy
Premerlani William James
General Electric Company
Metjahic Safet
Nguyen Vincent Q.
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