Vacuum circuit breakers in cable networks

The impact of switching over-voltages in a public distribution network on cable ageing and the occurrence of earth fault failure are discussed. It is concluded that 95% of the network remains unaffected by the behaviour of the VCB, and that switching over-voltages in the remaining connected Industrial sites don´t propagate into the public network. Hence, VCB behaviour cannot explain the increased earth fault failure rate observed in Russia.