Statistical processing of chopped currents and overvoltages in two types of sulphur hexafluoride breaker technology

Tests on breaking three-phase low inductive currents were carried out with two medium-voltage SF₆ breakers using different breaking techniques; the puffer method and the rotating arc. The statistical interpretation of the chopped currents and overvoltages produced by the two types of equipment showed that the two technologies performed satisfactorily, that is without excessive stresses for the system in service (in particular no successive restrikes on breaking) and with acceptable overvoltages caused by chopping. The typical values of the chopped currents measured were less than 1 A for rotating arc, and 3 to 8 A for puffer type circuit breaker. The overvoltages generated by the rotating arc circuit breaker (typically 2 p.u.) remain perceptibly lower than those caused by the other circuit breaker (typically 3 p.u.), even when using the former equipment at a voltage higher than its rated voltage. The results obtained are in line with the theory and experimental results