Comparison of IEC 60270 and RF partial discharge detection in an electromagnetic noise-free environment at differing pressures

Measuring partial discharge according to IEC60270 is a well established and widely accepted method. Unfortunately it presents some limitations especially when it is necessary to monitor the system under load conditions and when the localization of the discharge sources is demanded. To overcome these problems, other techniques have been developed in the last few years and one of the most promising methods is the on-line detection and localization of partial discharge using RF techniques. Work in this area, especially in the UHF band is an area that has been developing significantly in recent year. This paper describes initial results from the measurement system recently installed at the University of Manchester that is being used to compare IEC60270 and RF UHF detection methods in a controlled electromagnetic noise-free environment at a variety of pressures (10-101.3 kPa). The use of varying pressure reflects the need for partial discharge testing of equipment that will be operated in an aerospace environment as more-electric aircraft see high voltage power systems being deployed. The system is housed in a screened room built according to EN 50147-1 that provides a screening factor of at least 100 dB in the detected frequency band (1MHz-3GHz). The test set is equipped with a LEMKE LDS-6 PD measuring system, an ADVANTEST Spectrum Analyzer and an Agilent 6GHz oscilloscope. Several inhouse and commercial sensors have been tested with a range of scanning antennas. The facility has been developed to provide an understanding of RF detection in both standard and low pressure environments and to provide a tool to study the RF spectra emission associated with different PD sources. It is hoped that this will lead to the design of a RF-based PD detection monitoring system for power electronic systems used in a range of applications.