Characteristics of GIS disconnector-induced short rise-time transients incident on externally connected power system components

The authors provide an indication of the waveshape and magnitude of transients which emerge from the SF₆ GIS and propagate to externally connected apparatus. Capacitively graded bushings, overhead line connections, etc. tend to reduce the magnitude and cause a slight degradation in the rise-time. Computer simulations and measurements have shown that external apparatus connected to GIS can be subjected to waveforms with rise-times in the range of 10-20 ns and voltage rate-of-rise as high as 40 MV/μs. This is comparable to or in excess of the rate of rise during a chopped wave test