Key technologies for developing a 420 kV 50 kA GCB interrupter unit

Polytetrafluoroethylene (PTFE) has been widely used as nozzle material in puffer-type circuit breakers, but the irregular carbonization and under the exposure to interrupted arcs were not fully understood. The addition of a heat-resistant filler has been studied theoretically and experimentally. A model to simulate the wear of the nozzle material is proposed. The model assumes that the radiation energy from the arc is absorbed by the filler particle while the PTFE transmits the energy with negligible absorption. The wear rate reproduced by this model showed good agreement with the experimental results of nozzle wear for a 420 kV, 50 kA interrupter unit