Characterization of Partial Discharge Measuring Instruments by the Generation of Reference Insulation Defects in an Experimental Setup

Partial discharge (PD) measurement has become an effective laboratory and on-site test for the detection, identification and location of defects in the dielectrics of highvoltage (HV) electrical systems and thus to assess their insulation condition. Several PD instruments have been developed to carry out, in situ, on-line temporary or monitoring measurements. However, no standard exists to define what type of evaluation should be required to check the effectiveness of the PD measuring and diagnosis instrumentation implemented. The instruments used for on-line PD measurements must incorporate specific functional features to cope with the following drawbacks, in order to perform a proper diagnosis: the existence of high levels of background electrical noise, the simultaneous presence of multiple PD sources, and the difficulty of identifying the insulation defects and of determining their location. To overcome these drawbacks, adequate selection of the measuring technique and the implementation of effective signal processing tools is essential. In the research presented in this paper, a new method for the evaluation and qualification of the functional features of PD measuring and diagnostic instruments is presented. For the application of the proposed method, a scale modular HV setup has been designed and manufactured. In this setup reference time series of PD pulses are generated in a repetitive and controlled way in individual test cells with real insulation defects.