Novel Centralized Drive Circuit for Fast Vacuum Switches in Multiport DC Breaker

Multiport dc breaker (MP-CB) contains multiple fast vacuum switches (FVS) for long-term micro-operating losses, and usually only one FVS needs to operate when interrupting fault current. In existing MP-CB, the operating mechanism of each FVS, based on Thomson-coil-actuator (TCA), is configured with an independent drive circuit consisting of capacitor banks and thyristor modules, resulting in large-volume and high-cost. To tackle this problem, a novel centralized drive circuit is proposed for all FVS in MP-CB in this article. The main contribution of this article is by adding thyristor modules to ensure multiple FVSs, whose moving contacts are electrically connected together, could share the capacitor banks in the centralized drive circuit, reducing the cost and volume. Structure, working principle and mathematical model of the proposed drive circuit are presented. Taking three-port dc breaker as an example, experiments on prototype of FVS and the whole MP-CB (transient interruption voltage of 1.5 kV, interruption current of 2.9 kA) are conducted for verification. The research shows volume and cost of drive circuit for the operation of three FVS could be reduced by 58% and 43%, respectively.