To clarify the contact failure phenomena and their development in the Gas-Insulated Switchgear (GIS), tests were conducted by simulating abnormal current-carrying conditions using an actual 300kV-2, 000A GIS.
This paper describes the process observed in the range from contact failures to ground faults, deteriorative phenomena and some detection methods for initial contact failure conditions. A summary of this study is as follows;
(1) The contact resistances are greatly dependent on the materials and construction of contacts.
(2) The relation between the initial contact resisitance and the carried current resulting in an arcing is derived with approximately constant Joule-heat generation.
(3) Ground faults result from a sagging of a shield molten by arcing or a combination of two causes; (i) scattering of molten metal caused by arcing and (ii) sagging of a conductor caused by melting down of bolts.
(4) For detection of initial contact failures, it is recommended to observe the contact resistance, the temperature rise on the tank surface or the electrical partial discharges.
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