IEEE C37.20.9-2025

This standard covers the design, testing, and installation of metal-enclosed switchgear that incorporates gas (typically SF6) at higher than ambient pressure as an insulation medium for alternating-current applications rated above 1 kV to 52 kV. The contents of the switchgear may include but are not limited to circuit breakers, switches, bushings, buses, instrument transformers, cable terminations, instrumentation, metering and controls, and protective relays. In a vertical section of the switchgear, some or all of the medium-voltage compartment(s) shall be composed of a gas pressure system for the primary insulating medium. This standard covers various partition classes of switchgear (as described om Annex J) for both indoor and outdoor installations including isolated phase. This standard covers switchgear containing one or more phases. This standard also does not cover switchgear that is covered under IEEE Std C37.20.2™, IEEE Std C37.20.3™, or IEEE Std C37.74™-2014 [B38] that uses individual components that are gas-insulated such as switches, circuit breakers, and other equipment, nor does it fully cover those components that are covered by their individual component standards.



Revision Standard - Active. Metal-enclosed switchgear assemblies incorporating gas insulating systems containing, but not limited to, such devices as interrupter switches; selector switches; fuses; circuit breakers; control, instrumentation, and metering devices; and protective equipment are covered in this standard. Equipment for the control and protection of apparatus used for distribution of electrical power is also included, but not specifically limited to, in this standard.