Selection of Optimum Circuit Breaker for a Low-Voltage Industrial Power Distribution System

Low-voltage power distribution system in a commercial and industrial environment is controlled and protected mainly by air circuit breakers. It is essential that the breakers selected are fit for the duty they are required to perform. The strength and capability of the breakers selected should be such that they offer adequate protection to the associated equipment and do not give rise to any danger to the operating personnel. In order to comply with this requirement, the breakers selected should be able to interrupt the maximum prospective fault current and have adequate making current and short time current withstand capability. The determination of essential breaker current ratings is done by calculating maximum prospective making and breaking current at the point of breaker installation. The short time withstand current rating depends upon the number of breakers in series and their protection coordination. Hand calculations can be performed for simple system and power system analysis software tools may be used for complex networks. Zero-point quenching air circuit breaker is considered to determine the essential current parameters.