FTIR TECHNIQUE AS A MAINTENANCE TEST FOR PARTIAL DISCHARGES IN SF6 GAS-INSULATED SYSTEMS

In many high-voltage systems in general and in gas-insulated systems (GIS) in particular, partial discharges are an indication of insulation weakness which can lead to failure. The measurement of partial discharges has become a routine procedure for acceptance testing and maintenance of switchgear, transformers, power cables, etc. Partial discharges (PD) in sulphur hexafluoride SF6 gas-insulated systems can Affect very much its integrity. The Fourier Transform Infra-Red (FTIR) technique can be used to test the SF6 gas for impurities by comparing the standard SF6 spectra in its pure condition with other spectra of the gas in different contaminated condition. This paper will argue the use of FTIR as a technique to check the status of SF6 condition and to detect the presence of partial discharges in gas insulated systems. Preliminary results of SF6 gas samples, in different conditions, tested in a standard point-plane electrode geometry and stressed by a negative DC voltage will be presented, using FTIR analysis.