Multi-break arc interaction in the energy balance region

It is postulated that the performance of a multi-break interrupter can be better than that expected from an extrapolation of the test results on a single-break unit. A computer model was developed to study the interaction processes in the energy balance region under short line fault conditions, using a Mayr model differential equation to model arc behavior. This nonlinear equation and the equations representing the electrical network and fault condition were solved for variations in selected parameters and expected unbalances in the voltage distribution across the interrupter units. Comparisons were made between the simulation of a circuit breaker with two interrupting breaks and one with a single break and an equivalent voltage stress. In the neighborhood of criticality, the two-break configuration interrupted the fault current, whereas the single break failed. It was shown experimentally that for equivalent voltage stresses, a two-break interrupter reached the dielectric reignition phase, while the single-break reignited thermally. This supports a concept of sharing between breaks