IEEE C37.20.1-1993

This standard covers metal-enclosed low-voltage power circuit breaker switchgear assemblies containing, but not limited to, such devices as low-voltage power circuit breakers (fused or unfused); other interrupting devices; switches, control, instrumentation, and metering; and protective and regulating equipment. This standard is concerned with enclosed, rather than open, indoor and outdoor switchgear assemblies. It includes types of equipment that are part of secondary unit substations. It does not apply to equipment covered by industrial control standards, communication switchboards, communication switching equipment, switchboards for use on board ships, or dead-front distribution switchboards. In this standard, metal-enclosed low-voltage power circuit breaker switchgear shall be called LV switchgear. For ac LV switchgear, the voltage shall be 1000 V or below; for dc LV switchgear, the voltage shall be 3200 V or below.



Revision Standard - Superseded. This IEEE Standards product is part of the C37 family on Switchgear, Substations and Protective Relays. Low-votage metal-enclosed switchgear, which can contain either stationary or drawout, manually or electrically operated low-voltage ac or dc power circuit breakers in individual grounded metal compartments, in three-pole, two-pole, or single-pole construction is covered. Rated maximum voltage levels can be 254 V, 508 V, or 635 Vac and 300/325 Vm 800V, 1000 V, 1600V, or 3200 Vdc. The continuous current ratings of the main bus in ac designs can be 1600 A, 2000 A, 2500 A, 4000 A, 6000 A, 8000 A, 10 000 A, or 12 000 A. The switchgear can also contain associated control, instruments, metering, protective, and regulating devices as necessary. The standard deals with service conditions, rating, temperature limitations, and classification of insulating materials, insulation (dielectric) withstand voltage requirements, test procedures, and application.