Arc Model to Evaluate D.C. Interruption Performance for Molded Case Circuit Breaker

Abstract

Calculations of short line fault (SLF) interruption performance for high voltage gas circuit breakers have been made by using arc models. Cassie and Mayr arc model are well known as an arc model. By combining the one Cassie and two Mayr models, the SLF interruption performance for SF₆ gas circuit breaker and CO₂ gas circuit breaker is able to be evaluated. Recently, power distribution systems have been changing due to the spread of renewable energy sources. Molded Case Circuit Breaker (MCCB) will interrupt direct current. In this paper, arc model of the air arc was constructed to evaluate the D.C. interruption performance of the MCCB. In the MCCB arc model, the arc parameters which are arc time constant, arc voltage for the Cassie model, arc time constant, arc power loss for the Mayr model were obtained by arc voltage measurements. It is able to set the arc time constants for Cassie and Mayr models are the constant value same as the SF₆ gas circuit breaker and CO₂ gas circuit breaker. The relation between arc power loss for Mayr model and peak value of interrupting current was derived from measurements. It is shown that the D.C. interruption performance for MCCB can be evaluated by using serially connected three arc models same as SF₆ gas circuit breaker and CO₂ gas circuit breaker.