IEEE C37.20.7-2007

This guide establishes methods by which metal-enclosed switchgear, as defined by IEEE Std C37.20.1-2002, IEEE Std C37.20.2-1999, and IEEE Std C37.20.3-2001, may be tested for resistance to the effects of arcing due to an internal fault. This guide applies only to equipment utilizing air as the primary insulating medium and rated up to 38 kV ac. It applies to both indoor and outdoor equipment; however, special consideration must be given to the building size and construction for indoor applications (not addressed by this document). The tests and assessments described in this guide are only applicable to arcing faults occurring entirely in air within the enclosure when all doors and covers are properly secured. This guide does not apply to arcing faults that occur within components of the switchgear assembly, such as instrument transformers, sealed interrupting devices, fuses, and so on. Switchgear designs that meet the requirements of this guide will be referred to as arc-resistant, metal enclosed low-voltage ac power circuit breaker switchgear, arc-resistant metal-enclosed interrupter switchgear, or arc-resistant metal-clad switchgear as applicable, or generally, as arc-resistant switchgear. This project is intended to revise the existing C37.20.7 to harmonize with IEC documents, correct inconsistencies in the procedure, and add an application guide as an informative annex. The scope of C37.20.7 will also be extended to cover low-voltage metal-enclosed ac power circuit breaker switchgear. Revision Standard - Superseded. Revision of IEEE Std C37.20.7-2001. A procedure for testing and evaluating the performance of metal-enclosed switchgear for internal arcing faults is covered. A method of identifying the capabilities of this equipment is given. Service conditions, installation, and application of equipment are also discussed.