Commutating direct current out of a vacuum interrupter with a GTO thyristor

We have developed and demonstrated a novel method of commutating direct current out of a standard vacuum interrupter. The technique uses a high-current, gate-turn-off thyristor in series with the interrupter to extinguish the arc and allow the interrupter to clear. The commutation method has been used to design and fabricate a continuous duty switch that will switch off 1000 A in 100µs and develop 25 kV at a repetition rate of 5 Hz. We have completed preliminary tests and present the important design relationships and test data in this paper.