Analysis of Thermal Performance of an Air Circuit Breaker

The protective system is considered to be one of the most crucial parts of any electrical system. An air circuit breaker (ACB) is a protective device used in low voltage power systems to carry current in normal conditions and to isolate the circuit from fault during a faulty condition by opening its contacts. ACBs are generally used in switchboards. During a normal condition, the Amperes flowing through the conducting parts of ACB results in heat generation. This heat generated increases the overall temperature of the ACB. It is required that for the healthy operation of a circuit breaker, this temperature should be within specified limits as specified by the standard and efforts should be made to reduce it to enhance the performance of the circuit breaker. This paper analyses the ability of an ACB to generate and dissipate heat during normal condition i.e. when it is carrying the current. Initially, the thermal performance is analyzed using the thermal-electric finite element method on ANSYS software and then it will be verified using experimental trials. This paper also discusses some of the methods for improvement of the thermal performance of an ACB and the effect of length of the current path on the thermal performance of an ACB.