Design and Development of 10kA 1kV Synchronized Thyristor Based Static Switch for Evaluation of Breaking Performance of Low Voltage Circuit Breakers

The Point On Wave (POW) switching of a Make Switch (MS) is a prime requirement for short-circuit (SC) testing of various electrical equipment. The circuit closing shall occur at voltage zero to establish maximum asymmetry, which decides the dynamic peak current during short-circuit testing. In the case of Circuit Breakers (CB), the SC current will be limited considerably below its prospective value. The breaking capacity tests on Miniature Circuit Breakers(MCBs), as per IEC 60898–1 [1], demand that the MS be fast enough to close at different closing instances of the sinusoid input voltage waveform. Inconsistency in MS operation leads to improper closing angle for the test, thus invalidating the test. Hence, to evaluate the breaking performance of MCBs, a 10kA 1kV synchronized thyristor-based static switch is designed and developed in this research work. This work is the first attempt to develop such a static switch indigenous. This paper also discusses the effect of breaking current characteristics due to the variation of closing angle (initiation at which the SC occurs) through real-time experiments on 240V ac C6A 10kA Single Pole (SP) MCBs. This paper also analytically attempts to analyze the closing angle at which maximum energy occurs for the given fault level, further validating the significance of POW closing. From the overall analysis, this research investigation signifies the positive effects of mechanical force under short-circuit conditions.