Design and Operation of a Medium Voltage Pulse Test Apparatus for Short-Circuit Testing of DC Solid State Circuit Breakers

Testing of DC solid state circuit breakers (SSCB) over the full set of operating points requires a source capable of supplying short-circuit fault currents at the rated voltage. As the voltage and current levels of DC SSCBs increase, procurement of DC sources and loads capable of the required voltage and fault currents for development testing becomes impractical. This paper introduces a test circuit that enables fault interruption testing of an SSCB by dynamically switching between a low voltage, high current source and a pulse capacitor source. The circuit supplies rated current to a shorted SSCB at low voltage, allowing it to reach thermal equilibrium. Then a capacitor bank dynamically switches into the SSCB on top of the rated current, briefly providing a pulse at rated voltage that the SSCB can attempt to interrupt. The proposed pulse test circuit is designed using analytical models and simulations. The test circuit is then constructed and experimentally validated by testing a prototype 12 kV, 2kA, DC SSCB.