High Voltage SF6 Circuit Breaker Selection for a Substation

Modernizing high voltage substations by selecting proper gas circuit breakers is essential to meet the higher demands, new loads, and different load types. It ensures that the electricity supply is reliable and affordable to industrial and commercial customers. The critical issues are the asymmetric fault components on the high voltage side due to different dynamic loading scenarios among the customers. The gas circuit breaker selection must consider all the worst scenarios. This paper investigates a substation of 138 kV transmission and 13.2 kV distribution circuits. At varying dynamic loading, the asymmetrical fault current, critical parameters of the gas circuit breaker like the dc component, and the maximum fault current withstanding ability are analyzed. A procedure is proposed based on the steps required to plan and design a substation. Iteration is performed at different dynamic loading scenarios to select suitable gas circuit breakers to ensure reliable and optimal power flow through the substation.