Experimental Verification of a Hybrid DC Breaker Setup Up to 800V and 500A with Copper Contacts in Hydrogen Environment and Transversal Magnetic Field in Combination with an IGBT Module

Important components for future DC networks are suitable DC switching devices. Current research shows that hybrid DC breaker systems consisting of mechanical- and semiconductor switches have advantages over the individual components. This is especially true when the currents exceed 100 A and voltages reach 800 V. In this paper we focus on a basic structure of a hybrid DC breaker consisting of a parallel circuitry setup of a mechanical switching device (mechanical bypass switch), an power electronic switching device and a power dissipation component, all connected in series to a further mechanical switching device (mechanical disconnecting switch) for galvanic separation. Considering the mechanical bypass switch, this hybrid setup can shorten the arc duration significantly based on the commutation mechanisms between mechanical and semiconductor switching devices in combination with a metal oxide varistor. This commutation to the semiconductor branch can be accomplished through the voltage drop between the opening mechanical contacts. Therefore, this natural commutation process is investigated here in detail with a pair of copper contacts with additional hydrogen-nitrogen gas environment and/or transversal magnetic fields to enhance the effect of cooling the arc and to reduce reignition probability. Almost arc free switching up to 800 V from 100 A- 500 A is demonstrated for opening of the mechanical contacts with an IGBT in parallel connection. Several questions about contact erosion and wear are discussed.