A source transfer switch for the AC power source

This paper presents an automatic AC source transfer switch for broadcasting and communication equipment. Since the proposed transfer switch has a short transfer time under 4[msec], system power reset is prevented when the main source has a trouble as like a black-out. Although the proposed source transfer switch adopts relay as a switching device, the transfer time is under 500t⊘sec] when the main source is recovered, under voltage status, and overvoltage status. Moreover zero current switching is realized.