IEEE 340-1972
Voltage Circuit Breakers Rated on a Symmetrical Current Basis
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About This Item
340-1972 is a technical standard for voltage circuit breakers rated on a symmetrical current basis, providing guidance for how these devices are identified and evaluated in power, energy, and industrial applications. It is relevant where circuit breaker ratings must be stated and compared consistently, especially in components, circuits, devices, and systems that depend on reliable interruption performance. As an inactive standard, it is mainly useful for legacy reference, design review, or historical compliance checks.
Overview of 340-1972
The scope of 340-1972 centers on voltage circuit breakers and the use of symmetrical current as the basis for rating them. This matters in electrical engineering because symmetrical current values help define interrupting and withstand capabilities under standardized conditions. The document is most useful when reviewing breaker specifications, comparing equipment ratings, or interpreting older design and procurement records. For engineers and specifiers, it offers a focused reference for understanding how these circuit breakers were categorized and assessed.
Typical use cases
This standard is commonly consulted when evaluating medium or high voltage circuit breakers used in power distribution, industrial switchgear, and related electrical systems. It may support equipment selection, rating verification, and documentation review for installations where symmetrical current values are used in breaker specifications. It can also be helpful in maintenance, replacement planning, or legacy system studies where older breaker ratings need to be matched carefully to existing circuits and protection schemes.
Why it matters
Standards like 340-1972 help keep breaker ratings clear, consistent, and technically defensible. That supports safer design decisions, better procurement comparisons, and more reliable testing or acceptance reviews. In practice, a symmetrical-current basis can reduce ambiguity when assessing interrupting capability and system compatibility. Even though 340-1972 is inactive, it remains important for interpreting legacy documentation and maintaining continuity in engineering records, compliance checks, and equipment lifecycle management.
- Voltage circuit breaker rating basis
- Symmetrical current reference
- Legacy equipment interpretation
- Power and industrial electrical systems
- Publication Date: 1972
- Standard Status: Inactive
- Publisher: IEEE
- Subject: Power, Energy and Industry Applications; Components, Circuits, Devices and Systems
- Official IEEE: Doi link
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