IEEE C37.20.2-2015

This standard covers metal-clad switchgear containing, but 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 designing and testing of metal-clad 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 Revision Standard - Superseded. 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. Rated maximum voltage levels for metal-clad switchgear range from 4.76 kV to 38 kV with main bus continuous current ratings of 1200 A, 2000 A, 3000 A, and 4000 A. MC switchgear also contains associated control, instruments, metering, relaying, protective, and regulating devices, as necessary. Service conditions, ratings, temperature limitations and classification of insulating materials, insulation (dielectric) withstand voltage requirements, test procedures, and applications are discussed.