IEEE PC37.20.1

Revision Standard - Active - Draft.
Metal-enclosed, low-voltage switchgear which contains either stationary-mounted or drawout-mounted, manually or electrically operated low-voltage ac or dc power circuit breakers or low-voltage ac definite-purpose switching devices in individual metal compartments, in three-pole, four-pole, two-pole, or single-pole construction is covered. Rated maximum voltage levels are 254 V, 508 V, 635 V, 730 V, or 1058 V ac; and 300/325 V, 600 V, 800 V, 1000 V, 1200 V, 1500 V, 1600 V, or 3200 Vdc. The preferred continuous current ratings of the main bus in ac designs are 1600 A, 2000 A, 3000 A, 3200 A, 4000 A, 5000 A, 6000 A, 8000 A, or 10 000 A. For dc designs, the preferred ratings are 1600 A, 2000 A, 2500 A, 3000 A, 4000 A, 5000 A, 6000 A, 8000 A, 10 000 A, or 12 000 A. The switchgear may also contain associated control, instruments, metering, protective, and regulating devices as necessary. The standard deals with service conditions, ratings, temperature limitations, and classification of insulating materials, insulation (dielectric) withstand voltage requirements, test procedures, and application.

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 LV ac switchgear, the nominal system voltage shall be 1000 Vac or below; for LV dc switchgear, the rated maximum voltage shall be 3200 Vdc or below.
This standard:
a) Establishes minimal functional requirements
b) Establishes preferred rating structure
c) Provides preferred ratings
d) Establishes design and production testing