Abstract: A cylindrical coil electrode incorporated in a vacuum interrupter comprises a cylindrical body having an opening at one end thereof, two electrical connections provided between the edge surface of the opening of the cylindrical body and a main electrode, two arcuate slits formed on the cylindrical body between the two electrical connections, two arcuate current paths formed in the cylindrical body by the arcuate slits beginning as a respective electrical connection and ending at a rod, and two current blocking slits formed on the cylindrical body at positions where one end of each of the current paths laps the other end of the other current paths. Because of the above structure, one-turn current flows throughout the current paths so that a uniform axial magnetic field can be applied to the main electrode, and an arc current can be uniformly distributed over the entire surface of the main electrode, thereby improving the current interruption performance of the vacuum interrupter.

Abstract: A puffer type gas circuit breaker comprises a first and a second arcing electrodes movable relative to each other, an insulating nozzle surrounding the second arcing electrode, a puffer device for introducing an arc-suppressing gas into the insulating nozzle to puff out the arc produced between the two arcing electrodes when the breaker is in motion for circuit breaking, and a movable shield device for relieving the concentration of an electric field at the front end of the first arcing electrode during the breaker motion for circuit breaking. When the breaker is closed and the circuit made, the movable shield device surrounds the first arcing electrode and insulating nozzle, with a predetermined gap between itself and the insulating nozzle opposite thereto, and is kept at the same potential as the first arcing electrode. The circuit breaker further includes a device for maintaining the predetermined gap and the same potential at least in the early stage of the breaker motion for current breaking.