Method and system for measuring partial discharge

Abstract

Prior to the measurement of partial discharge, a voltage detected by the antenna is inputted into a spectrum analyzer, a phase difference between an operating voltage and a power supply of the spectrum analyzer is obtained by phase domain analysis using the spectrum analyzer. Based on the phase difference and the voltage phase shift associated with input impedance of the signal converter circuit, the time axis displayed on the screen of the spectrum analyzer is compensated. After the compensation has been carried out, the voltage detected by the antenna is inputted into the spectrum analyzer, the partial discharge pattern which synchronizes with the operating voltage is measured by phase domain analysis using the spectrum analyzer.

1 . A method of measuring partial discharge, comprising the steps of: 
 detecting an operating voltage supplied to a conductor encased in a container together with an insulation material;    detecting a phase difference between a power supply voltage of a measuring instrument which displays input information on the screen and said detected operating voltage;    compensating the phase of the time axis displayed on the screen of said measuring instrument according to said detected phase difference;    detecting and inputting voltage of said conductor into said compensated measuring instrument; and    displaying partial discharge information, based on said inputted voltage, on the screen of said measuring instrument.    
   
   
       2 . A method of measuring partial discharge according to  claim 1 , wherein said step of detecting an operating voltage comprising steps of: 
 detecting voltage of the conductor; and    converting said detected voltages to a waveform of an operating voltage applied to said conductor by using a signal converter circuit.    
   
   
       3 . A method of measuring partial discharge according to  claim 2 , wherein said step of compensating the phase including step of: 
 compensating the phase of the time axis displayed on the screen of said measuring instrument according to said detected phase difference and a voltage phase shift associated with input impedance of said signal converter circuit.    
   
   
       4 . A method of measuring partial discharge according to  claim 1 , including the steps of: 
 detecting voltage of a conductor encased in a container together with an insulation material at different locations;    converting a waveform of an operating voltage, among said detected voltages, applied to said conductor by using a signal converter circuit;    inputting said converted operating voltage, via a delay circuit, into the trigger signal input terminal of a measuring instrument which displays input information on the screen;    inputting the other voltage, among said detected voltages, into the measurement signal input terminal of said measuring instrument; and    displaying voltage information inputted into said measurement signal input terminal on the screen of said measuring instrument using an operating voltage inputted into said trigger signal input terminal as a trigger.    
   
   
       5 . A partial discharge measuring system comprising: 
 a voltage sensor which detects an operating voltage supplied to a conductor encased in a container together with an insulation material;    a measuring instrument which displays input information on the screen,    a phase difference detecting means for detecting a phase difference between a power supply voltage of the measuring instrument and said detected operating voltage;    a phase compensating means for compensating the phase of the time axis displayed on the screen of said measuring instrument according to said detected phase difference;    a detecting means for detecting voltage of said conductor;    an inputting means for inputting said detected voltage into said compensated measuring instrument; and    a displaying control means for displaying partial discharge information, based on said inputted voltage, on the screen of said measuring instrument.    
   
   
       6 . A partial discharge measuring system according to  claim 5 , wherein said voltage sensor comprising: 
 a voltage detecting means for detecting voltage of the conductor; and    a signal converter circuit for converting said detected voltages to a waveform of an operating voltage applied to said conductor.    
   
   
       7 . A partial discharge measuring system according to  claim 6 , wherein said phase compensating means compensates the phase of the time axis displayed on the screen of said measuring instrument according to said detected phase difference and a voltage phase shift associated with input impedance of said signal converter circuit.  
   
   
       8 . A partial discharge measuring system according to  claim 5 , including: 
 a voltage detecting means for detecting voltage of a conductor encased in a container together with an insulation material at different locations;    a signal converter circuit for converting said detected voltages to a waveform of an operating voltage applied to said conductor;    the first inputting means for inputting said converted operating voltage, via a delay circuit, into the trigger signal input terminal of a measuring instrument which displays input information on the screen;    the second inputting means for inputting the other voltage, among said detected voltages, into the measurement signal input terminal of said measuring instrument; and    a displaying means for displaying voltage information inputted into said measurement signal input terminal on the screen of said measuring instrument using an operating voltage inputted into said trigger signal input terminal as a trigger.    
   
   
       9 . A partial discharge measuring system according to  claim 6 , wherein 
 said signal converter circuit comprises    a comparator which responds to an operating voltage detected by said voltage sensor and converts the waveform of said operating voltage to a square-wave,    a half-wave rectification circuit which half-wave rectifies the square-wave outputted by said comparator, and    an oscillation circuit which converts an output voltage of said half-wave rectification circuit into a voltage of higher frequency than that of said operating voltage.    
   
   
       10 . A partial discharge measuring system according to  claim 5 , wherein 
 said measuring instrument is a spectrum analyzer.    
   
   
       11 . A partial discharge measuring system according to  claim 5 , wherein 
 said measuring instrument is an oscilloscope.    
   
   
       12 . A partial discharge measuring system according to  claim 5 , wherein 
 said container is connected to a switchgear encasing container which encases a gas insulated switchgear, and said conductor is connected to an electrode of said gas insulated switchgear.