High-Frequency Effects in SF Circuit Breakers

To gain an increased understanding of circuit- breaker performance, and the corresponding specification and test issues, the interaction between circuit breaker and the connected network is being studied. In the course of this investigation, the modeling of high-frequency voltage transients is being addressed. The essence of the problem lies in the need to combine the electromagnetic modeling of the distributed nature of the interrupter, with the modeling of connected networks by lumped circuits and with the modeling of the electric arc plasma within the interrupter. An equivalent circuits approach is proposed for combining different levels of approximation within each modeling domain and to provide computationally economic solutions. A hierarchy of model approximations is presented and examples of their applicability are given. As a result, an insight into a number of factors (e.g., network transients, current chopping, interrupter geometry, etc.) which produce and affect high-frequency overvoltages have been produced.