IEEE C37.04i-1991

C37.04i-1991 is a technical standard for voltage circuit breakers rated on a symmetrical current basis, with clear relevance to power, energy, and industrial applications. It helps define how these breakers are specified, rated, and compared in service, supporting more consistent equipment selection and documentation. For engineers, buyers, and maintenance teams, the standard provides a common framework for understanding interrupting and rating requirements in electrical systems where dependable switching and fault protection are essential.

C37.04i-1991 overview

This standard focuses on the rating basis used for voltage circuit breakers, especially the symmetrical current values that support performance evaluation and equipment comparison. In practical terms, C37.04i-1991 helps align breaker ratings with the electrical conditions they are intended to handle, which is important when reviewing design limits, procurement specifications, or test expectations. It is a useful reference where breaker performance must be described with precision and interpreted consistently across engineering and operations teams.

Typical use cases

C37.04i-1991 is typically used when selecting or specifying voltage circuit breakers for substations, industrial power distribution, and other electrical installations that rely on standardized rating practices. It may also support equipment documentation, bid reviews, and maintenance planning where symmetrical current ratings must be understood clearly. In power and energy environments, the standard can help coordinate breaker selection with system protection requirements, fault-duty expectations, and overall switching equipment compatibility.

Why this standard matters

Using C37.04i-1991 helps reduce ambiguity in breaker rating interpretation, which matters during design review, procurement, testing, and compliance checks. Clear rating definitions can improve consistency between manufacturers, engineers, and end users, especially when comparing equipment for the same electrical duty. For organizations managing reliability and safety, the standard supports better decision-making around breaker suitability, helping limit performance mismatches and avoid costly specification errors.

• Voltage circuit breaker rating basis
• Symmetrical current definitions
• Power and industrial electrical systems
• Specification and procurement reference
• Performance comparison and compliance review