Type tests of switches for the ITER coil power supply system

In ITER, the interruption of high DC currents is required for plasma initiation at the beginning of each operation cycle and for protection of the superconductive coils in case of quench. Particularly, the high voltage needed for breakdown and plasma initiation will be provided by Switching Network Units (SNU), while Fast Discharge Units (FDU) will provide protection of the coils by extracting the energy stored in magnet field [1]. After a short description of the design, the paper focuses on the procedures and results of the type tests performed on the full-scale prototypes of main SNU and FDU power switches, which were manufactured after completion of the preliminary design phase at the beginning of 2012. The test program that was implemented during three years (in 2013–2015), among a number of electrical, hydraulic and functional tests, included life-time tests with rated currents, mechanical endurance tests for SNU switches and reliability tests for backup circuit-breaker. The successful results of the type tests confirmed the suitability of switch design and compliance with ITER requirements and made it possible to start manufacturing of the switches for delivery to the ITER Site. ITER is a Nuclear Facility, classified by the French Authority as INB-174.