电路相关acoustic emission analysis of high voltage insulation.pdfVIP

NON-DESTRUCTIVEDIAGNOSTICS OF INSULATING SYSTEMS Acoustic emission analysis of high voltage insulation B.R.Varlow, D.W.Auckland, C.D.Smith and J.Zhao Abstract: A portable acoustic emission monitoring system has been developed and used to test both laboratory samples and practical equipment. A fibre optic cable provides electrical isolation and protection for the operator and the monitor. Th~shas been tested on high voltage equipment up to 400kV. In laboratory samples it has been possible to distinguish between discharges arising from different sources by converting the acoustic emission signal from the time domain to the frequency domain by fast Fourier transformation and recognition of the frequency spectra (‘signatures’) thus produced. By a similar procedure it has been possible to discriminate between signals generated by discharge activity in oil in a ring main unit, in the oil alone and in oil containing dry and wet fibres. The optically isolated acoustic emission detector has been successfully used to locate and identify a number of practical sources of discharge activity, for example in transformer tanks and cable terminations. A portable system, including the detection and signal processing capability, has been developed and installed for the on-line monitoring of substation equipment. 1 Introduction exceed a preset acoustic threshold are acquired, for exam- ple, by a fast oscilloscope, and are analysed. They first The inability to predict incipient ageing effects leading to undergo fast Fourier transformation (FFT) from the time electrical breakd