Series resonance voltage-withstanding partial-discharge test method utilizing frequency modulation phase shift

Abstract

The invention discloses a series resonance voltage-withstanding partial-discharge test method utilizing frequency modulation phase shift, and relates to alternating current voltage-withstanding and partial-discharge test of electrical equipment. According to the series resonance voltage-withstanding partial-discharge test method utilizing frequency modulation phase shift, a frequency modulation series resonance voltage-withstanding partial-discharge test system composed of a rectangular wave variable-frequency power source, a resonant electric reactor, a partial-discharge instrument and the like is utilized, excitation voltage frequency is down-regulated when a resonance voltage reaches a set value of the test voltage, the system deviates from the resonant state and produces phase shift, four burrs (namely interference signals) formed on a time base of the partial-discharge instrument when a variable-frequency power source switching tube is switched on and switched off are moved to second and fourth quadrants rightwards from positions distributed on two edges of + / - 90 degrees, the excitation voltage pulse width is increased to enable the resonance voltage to reach the set value of the test voltage again, and then windows can be opened at first and third quadrants for partial discharge test of tested products. By means of the series resonance voltage-withstanding partial-discharge test method, interference on the partial-discharge test, caused by variable-frequency power source switching pulses, is avoided, the fact that people doubt whether windowing or blanking eliminates the partial discharge of the tested products is avoided, and therefore the reliable and high-efficiency rectangular wave variable-frequency power source is used for the voltage-withstanding partial-discharge test of various kinds of electrical equipment.

Description

technical field [0001] The invention relates to the electric insulation performance test of the electric equipment, especially the AC withstand voltage and partial discharge test of the electric equipment. Background technique [0002] Before the power line is put into operation or after the overhaul, the insulation state of the power components or equipment must be inspected and evaluated. Among these tests, AC withstand voltage is a basic and important test, while partial discharge measurement is a more advanced test method developed in recent years with the functions of early diagnosis of insulation state and prediction of development trend. Both tests require the application of AC high voltage to the test object. [0003] There are three basic methods of applying AC high voltage: external application method, induction method and resonance method. The resonance method is to use a reactor and the tested product (equivalent to a capacitor) to form an LC circuit, and make ...

AI Technical Summary

Problems solved by technology

This power supply basically has no interference, but it has low efficiency, high noise, large volume and poor reliability; while the previous partial discharge test systems using rectangular wave or square wave frequency conversion power supply have high power efficiency, small volume and reliable operation, but The burrs generated when the switch tube is turned on and off will affect the partial discharge measurement

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