Method and system for corona source location by acoustic signal detection
AssigneeGeneral Electric Company
InventorBernard Darrel
Life of this patent
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Abstract
To locate a corona fault in a transformer or other encased electrical apparatus by determining the propagation time for acoustic noise generated by a corona discharge, the electrical corona signal is gated and level-detected during an interval which is adjustable as to delay and length to thereby generate a timing reference to initiate acoustic signal averaging. The corona pulse can be found that results in an optimum signal-to-noise ratio in the acoustic signal being averaged, as is needed with limited test data in a noisy or reverberant acoustic environment. Also, multiple corona sources can be located.
Claims12
The method of locating a corona source within the housing of encased electrical apparatus having a high potential conductor comprising the steps of
- sensing at a known acoustic transducer position the acoustic vibrations within the housing including those produced by a corona discharge at the corona source, and generating an acoustic electrical signal representative of said acoustic vibrations,
- effecting filtering the voltage at said high potential conductor to derive an excitation frequency component signal and a radio frequency component corona signal caused by electrical disturbances accompanying corona discharge,
- cyclically gating said corona signal during a preselected gating interval which has an adjustable delay with respect to a reference on said excitation frequency signal to thereby find a corona pulse that results in an acceptable signal-to-noise ratio in the acoustic signal being averaged,
- level-detecting the gated corona signal and generating a timing reference to initiate acoustic signal averaging upon detecting a predetermined corona signal amplitude,
- repeatedly averaging said acoustic signal over a preset period and generating an averaged acoustic signal, and
- displaying said averaged acoustic signal to provide an indication of the distance from the known acoustic transducer position to the corona source.
A corona fault locating system for determining the location of one or more corona sources within the housing of encased electrical apparatus having a high potential conductor, said system comprising
- an acoustic transducer mounted at a known position for sensing the acoustic vibrations within the housing including those produced by a corona discharge at the corona source and for generating an acoustic electrical signal representative of said acoustic vibrations,
- filter means for filtering a voltage proportional to the voltage at said high potential conductor to derive an excitation frequency component signal and a radio frequency component corona signal caused by electrical disturbances accompanying corona discharge,
- adjustable corona signal gating means for cyclically gating said corona signal to a level detector only during a preselected gating interval which has an adjustable delay with respect to a reference derived from said excitation frequency signal whereby various corona pulses can be selected for level detecting,
- said level detector being operative to generate an output timing reference pulse upon detecting a predetermined corona signal amplitude occurring during the gating interval,
- a signal averager to which said acoustic signal is fed continuously, said signal averager being repeatedly triggered by said timing reference pulse to repeatedly average said acoustic signal over a preset period and generate an averaged acoustic signal, and
- means for displaying said averaged acoustic signal to provide an indication of the distance from the known acoustic transducer position to the corona source.
Dependencies are inferred from the claim text.