Operation and Maintenance

This chapter focuses on gas‐insulated substation (GIS) operations and maintenance. It explains the nature and sources of faults including their repair. Common maintenance procedures on measures to define the quality of the insulating gas (SF₆), visual and optical inspections, gas handling records, and leak detection methods are addressed. The chapter explains specific practices with respect to interlocks, gas zone management, spare parts, and special tools. Information is given on the types of expected failures, which require repair of a GIS, how much time is required to effect repairs, and how service continuity is related to the design. The chapter also explains how a GIS can be extended after it has been installed and operated for many years. Retrofit or upgrade of GIS is also explained. The case of overloading GIS is explained in section on overloading and thermal limits of the GIS for typical ratings of 1250A up to 6300A rated continuous current.