Mitsubishi Denki Kabushiki Kaisha

The Kansai Electric Power Co., Inc.

Keiichi Itoh

Kenji Morimoto

Yoshiharu Kaneda

Ken Kimura

Takaho Tanaka

Hideki Tokura

Shigeo Kitamura

Tetsu Shiota

A defect detecting apparatus for monitoring an electrical equipment for defects, the electrical equipment having a resonance frequency. The defect detecting apparatus includes a sensor operatively connected to the electrical equipment for sensing a signal indicating a defect in the electrical equipment; a first bandpass filter operatively connected to the sensor, the first bandpass filter having a first bandwidth and first center frequency at substantially the resonance frequency of the electrical equipment; a second bandpass filter operatively connected to the sensor, the second bandpass filter having a second bandwidth and a second center frequency higher than the resonance frequency of the electrical equipment; a signal strength comparing circuit operatively connected to the first bandpass filter and the second bandpass filter for comparing relative strengths of signals output by the first bandpass filter and the second bandpass filter; and a partial discharge measuring circuit operatively connected to the signal strength comparing circuit for measuring an output signal of the first bandpass filter relative to an output signal of the second bandpass filter to indicate a defect in the electrical equipment.

Abnormality detecting method and apparatus for electrical equipment,

An abnormality detecting method and apparatus for electrical equipment measures the frequency spectrum of a signal detected by a partial discharge sensor and detects a partial discharge signal having a frequency component in the neighborhood of a resonance frequency to detect the abnormality of the electrical equipment. The resonance frequency is determined on the basis of the electrical equipment and the measuring circuit. Where the electrical equipment is a rotating electric machine, the resonance frequency is determined on the basis of the length of the stator core, and a narrow bandpass filter circuit passes a frequency component around a resonance frequency to detect a partial discharge signal from the passed signal.

Abnormality detecting apparatus for electric equipment, particularly for

The abnormality detecting method and apparatus for electric equipment measure the frequency spectrum of a signal detected by a partial discharge sensor 9, and detect a partial discharge signal having a frequency component in the neighborhood of a resonance frequency determined on the basis of the electric equipment and its measuring circuit, then detect the abnormality of the electric equipment. In a rotating electric machine particularly, the narrow band filter circuit 23 passes a frequency component around a resonance frequency determined on the basis of the length of the stator core to detect a partial discharge signal from the passed signal.

Abnormality detecting method and apparatus for electric equipment,

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Hyogo, Japan

Keiichi Itoh