TFTR ECS safety ground switch soft close modification

The safety disconnect and grounding switches represent a major group of components used to support the Tokamak Fusion Test Reactor. There are fifteen such switches in the TFTR power conversion TF and PF coil system. These switches are metal enclosed DC equipment, rated at 15 kV (2500 amperes continuous). They contain gapless zinc oxide arrestors, a stored-energy-operated, double-pole, single-throw grounding switch (capable of closing in on an 80 kA load current), a double-pole, single-throw disconnect switch (to isolate the load from the power supplies), and polarity reversal bus links. In addition to circuit protection the switches provide a level of electrical isolation when it is necessary to access the DC side of the machinery. The operation of the stored energy grounding switches are the subject of this paper.