IEEE 339-1972

339-1972 is a technical standard for impulse voltage insulation strength in AC high voltage circuit breakers rated on a symmetrical current basis, with coverage for equipment at 362 kB and above. It addresses how these breakers are expected to withstand high-voltage transients without insulation failure, supporting dependable design and evaluation in power system applications. For engineers and buyers working with high-voltage apparatus, this document helps define a clear performance reference for insulation capability and testing expectations.

339-1972 overview

This standard sets out the insulation-strength context for AC high voltage circuit breakers where impulse voltage performance is a critical design concern. The focus is on breakers rated on a symmetrical current basis, which ties the document to electrical equipment used in demanding transmission and substation environments. As a reference for 339-1972, it helps frame the relationship between voltage stress, insulation coordination, and the suitability of breaker designs for higher-capacity service conditions.

Typical use cases

339-1972 is typically relevant when specifying, testing, or reviewing AC high voltage circuit breakers intended for utility transmission networks, substations, and other power infrastructure using 362 kB and above equipment. It may be used during procurement to compare insulation performance criteria, in engineering reviews for breaker selection, or in test planning for impulse withstand verification. The standard is also useful when coordinating breaker insulation with adjacent system components and operating voltages.

Why this standard matters

For high-voltage switching equipment, insulation performance is closely tied to system reliability and personnel safety. 339-1972 provides a defined technical basis for checking whether a circuit breaker can tolerate impulse voltage stresses associated with real operating conditions and network disturbances. That matters for design control, compliance reviews, and acceptance testing, especially where consistent ratings are needed across projects. Using the standard can reduce ambiguity in specification and help lower the risk of insulation-related failures.

• Impulse voltage insulation strength
• AC high voltage circuit breakers
• Symmetrical current basis ratings
• 362 kB and above equipment
• Testing and specification reference