Thermal Analysis of Air Circuit Breaker

Abstract

Circuit breaker is a switchgear which carries rated current under normal operating condition protect system against fault conditions. Air circuit breaker is a type of breaker which is generally operated at low voltage and current range of 400-6300 Amp. Heat generated in CB, during normal operating condition which lead to increase its temperature. Metal parts in current path dissipate large amount of heat while carrying rated current because of eddy current losses. As a result, there is a rise in temperature of the breaker throughout the current path. These eddy current losses are dependent on the material used along the current path. Temperature rise test is conducted to check thermal performance of the product at rated operating current. Temperature rise in the breaker should remain within the standard specified limit as specified by the standard. By use of different type of non-magnetic material, it is possible to reduce eddy current losses in the ACB, thereby reducing overall heat generation of the product. This may result into lower value of temperature rise. Therefore, thermal analysis is being carried out to study the effect of eddy current losses on temperature rise along the breaker current path and accordingly possible options to reduce eddy current losses are being worked out.