New Developments in Design and Testing of HVDC Circuit Breakers

HVDC load breakers using AC circuit breakers combined with parallel circuits are proposed. The choice of parallel circuitry depends upon the kind of AC circuit breaker used. When using non linear (temperature dependent) resistors great improvements can be achieved in counter voltage generating and energy absorbing capabilities, as compared to earlier circuits using commutating capacitors and silicon carbide resistors. Switching units and suitable bypasses are investigated in details. Test circuits for testing the commutating switches and for testing the complete HVDC load breaker are also treated.