Exchange of conventional type of generator breakers to vacuum breakers in power stations

Refurbishing electrical plants may involve use of newly developed equipment in combination with the existing old machinery designed to cope with equipment of earlier design. Generator breakers installed some decades ago might occupy a lot of space, use substantial auxiliary supply of electricity, compressed air etc. and are often costly to maintain with spare parts running out of stock. The modern type of breakers, for instance the minimum oil, SF₆ and vacuum breakers, are very efficient and offer advantages on costs for installation and maintenance. One main concern is whether their effective current switching ability might cause transient overvoltages deteriorating the insulation of the generator windings. The authors deal with an exchange of the air blast type generator breakers to vacuum breakers in Storfinnforsen hydro power station in Sweden