Auto-check circuit breaker interrupting capabilities

Circuit breakers in a utility network are designed to quickly isolate short-circuited equipment from the rest of the system. The short-circuit current changes with switching operations and with the addition and removal of generating sources. Hence, electric utilities must check their breakers periodically using computer simulation to ensure that the breakers are capable of interrupting the short-circuit currents. The recent proliferation of independent power producers (IPP) has made breaker-rating studies a much more routine procedure for utility engineers. The aim of these studies is to see if the existing circuit breakers are adequate when the proposed generators are put in service. The need for efficient and accurate breaker-rating software is greater now than ever. The benefit of computerized breaker-rating studies has been recognized for many years. Most utilities have breaker-rating software of some kind. What is not well known about breaker rating is the inherent difficulty in rating breakers using the sequence-network model that is commonly used for short-circuit studies. The breaker-rating program was improved by making the description of the breaker more flexible, universal, and easy to apply. This is the breaker connection model.Once breaker data is entered into a database, a breaker-rating program greatly reduces the time and effort required to ensure that breakers will work property in the event of a fault.