Calibration of Partial Discharge Measuring System by a Reference Square Wave

Abstract

The Paper is about method of calibrating partial discharge measuring device. The measuring system captures the current impulses in the leads of the sample are then transformed into voltage impulses by rejecting any disturbances caused by high voltage source. These pulses are amplified and analysed in digital storage oscilloscope and PC Based analyzer. Before conducting partial discharge test with high voltage source, a pulse of known charge value is fed into the measuring circuit for calibration of the system and the scale factor of the PD measuring system is determined as per the Standard. This calibration assures the “apparent PD Magnitude” is measured correctly. The calibrator need to be calibrated periodically before the actual measurement. This operation is performed by applying a square wave of known amplitude to a series capacitor through matching impedance & amplifier circuit.  A labview program is developed to measure the number of PD pulses obtained for different frequencies of input square wave. The results obtained characterize the partial discharge measuring system behavior.