Recently updated on Maggio 11th, 2021 at 08:53 am

CESI Experience on Diagnostics of Electrical Components Michel de Nigrisa , Wojciech Kołtunowicza Cesi S.p.A., Centro Elettrotecnico Sperimentale Italiano, Via Rubattino, 54, Milan 20134, Italy

Abstract The paper describes some of the recent activities in CESI aimed at the determination and application of the most effective diagnostic indicators and on the selection of the best diagnostic techniques for power transformers, power cables and high voltage GIS equipment. In particular, for power transformers, diagnostic methods to monitor insulation deterioration and winding geometrical deformation are taken into account. A laboratory and field application of Sweep Frequency Response Analysis Method (SFRA) is described. The results of SFRA method are referred to leakage reactance measurements made with traditional bridge method. The extensive activity was carried out to identify the most appropriate diagnostic indicators for different types of power cables insulation (impregnated paper, rubber, PVC, XLPE). The effectiveness of modern condition assessment systems for defects evaluation in medium voltage cables have been compared in laboratory and during field measurements. For GIS equipment, the sensitivity of electrical, optical and acoustic method for partial discharge (PD) detection is simultaneously verified in laboratory and their applications during on-site testing and in service is discussed. The sensitivity of these methods to detect and recognize different GIS defects is verified for the most common defects of critical size and very low apparent charge values. For on-line monitoring of PD a new optical system has been developed. The system uses a high sensitive photon counting technique based on the detection of light emitted as a result of ionization and recombination processes accompanying PD activity caused by internal defects.