IEEE C37.20.2-2022

This standard covers metal-clad switchgear assemblies where air at ambient pressure is the primary insulating medium. The switchgear contains, but is not limited to, such devices as power circuit breakers, other interrupting devices, switches, control, instrumentation and metering, and protective and regulating equipment. It includes, but is not specifically limited to, equipment for the control and protection of apparatus used for power generation, conversion, and transmission and distribution. This standard is concerned with enclosed, rather than open, indoor and outdoor switchgear assemblies rated above 1000 V ac. Included is equipment that is part of primary and secondary unit substations. Gas-insulated substation equipment is not included. In this standard, metal-clad switchgear will be called MC switchgear.

This standard provides information essential to the designing and testing of MC switchgear. Included herein are preferred ratings, required design test procedures, and acceptance criteria. A detailed description of construction requirements, including required functional performance features, structural materials, insulation, and interlocking, is provided. Additionally, information on equipment application with respect to operating conditions, dielectric capabilities, and detailed application information regarding continuous current capabilities under differing ambient temperature conditions and application involving short-term overloading is included.

Revision Standard - Active. Metal-clad (MC) medium-voltage switchgear that contains drawout electrically operated circuit breakers is covered. MC switchgear is compartmentalized to isolate components such as instrumentation, main bus, and both incoming and outgoing connections with grounded metal barriers. Ranges from 4.76 kV to 48.3 kV with main bus continuous current ratings of 1200 A, 2000 A, 3000 A, and 4000 A are the rated maximum voltage levels for metal-clad switchgear . Associated control, instruments, metering, relaying, protective, and regulating devices, as necessary, are also contained by MC switchgear. Service conditions, ratings, temperature limitations and classification of insulating materials, insulation (dielectric) withstand voltage requirements, test procedures, and applications are discussed.