CASE STUDY ON GIS DEFECTS AND NEW POSSIBILITIES FOR PREVENTIVE MAINTENANCES

The paper reports on the practical aspects of diagnosis of gas insulated systems (GIS). The defects frequency in a GIS probably reflects the care taken during assembling, com-missioning and in-service. A preventive maintenance system for gas insulated system (GIS) is suggested. This new system serves for diagnosing defects and injecting different types of gases into the section where corona discharges (CD) or particle discharges (PD) are occurring. Automatic injection of SF6 gas and/or a special gas mixture improves the dielectric strength and so prevents faults in service. Criteria for source discrimination, localisation and evaluation for the developed system are discussed