Counter pulse capacitor bank for 70 kA, 10 kV commutation system

The capacitor banks are intended for generation of the counter current pulse in vacuum circuit breakers of a two-step powerful contactor (switchgear). This switchgear is part of the power supply system of ITER superconductive coils and provides fast discharge of coil magnetic field energy by breaking the coil current supply loop and connecting in the loop the high energy resistors. The superconductive coils of the ITER facility store considerable energy (several gigajoules) and the counter pulse capacitor bank should generate the pulse current not less than 70 kA during about 600 μs at an initial voltage up to 10 kV. After generation of the current pulse the discharge switch of the capacitor bank is closed and a high voltage exceeding the initial one (10 kV) is applied to the discharge switch. The paper presents the features of the transients during the commutation cycle, design of the capacitor bank and its main components (semiconductor discharge switch, inductor, charger, etc.), as well as the results of the capacitor bank testing.