Computer-aided selection and verification of circuit breakers

Procedures governing medium- and high-voltage breaker application, although conceptually tractable, tend to be repetitive for large systems. Hand calculations can become quite laborious when assessing safety margins of installed switchgear on systems that have experienced sudden growth. This article describes how a computer can be used as an efficient tool to address these concerns. The discussion focuses on how the computer can be used to interface the short circuit study results to the breaker modules, on how breaker adequacy evaluation can be computerized, and finally how these calculations can be extended to yield automated breaker selection according to user-defined criteria and breaker rating structures. The discussion is confined to the North American breaker application procedures and rating structures as tabulated in the ANSI Standards, and addresses only short circuit current interrupting requirements