A new fault current detection technique for the ac hybrid circuit breaker

Abstract

This paper attempts to introduce a new technique for the short-circuit currents detection in the low voltage installations, also to present the applications of the suggested technique with the hybrid circuit breaker HCB. The results carried out on the experimental model of the HCB (based on current magnitude discrimination) have drawn an attention that the short-circuit detection system SDS has limited the main features of the HCB. In order to assure contacts separation at zero current, high reliability with minimum component, precise overload discrimination, reduction of the let-through current and recovery voltage the new technique has been introduced. The new technique involves a fault detection using rate of current rise rather than the current magnitude and a time delay operating characteristic based on experimental and simulated data. The simulated results showed that the HCB succeeded to separate the main contact at zero current under all fault circumstances.