Development of monitoring and diagnostic system for SF/sub 6/ gas insulated switchgear

In this paper, we roughly describe the principles and structures for the sensor applications and diagnostic algorithm together with networking and monitoring system for GIS. Firstly, we describe the detailed specifications and the results of research, and then present the experimental results of the diagnostic algorithm for GIS. For the diagnosis of mechanical operation, we used auxiliary CT (current transformer) and auxiliary contacts as a sensor. Experiments were performed in general and extreme conditions to establish the standard values that can evaluate the condition of mechanical operation, and then standard values were established to prevent faults. Techniques that monitor leakage current of a zinc-oxide lightning arrester are described with results of laboratory test. Methods are also described to detect partial discharge and internal fault location, as well as to monitor gas pressure. Finally, the results of the application on 72.5 kV GIS and 170 kV GIS in real substations are presented.