A general survey of the high-tension switchgear field

The object of the paper is to aid the operating engineer in laying out high-tension switchgear schemes. It deals with the evolution of switchgear, giving the contributing factors in its development. The present-day types are scheduled and the principal features compared in the light of the Requirements of good switchgear. The most suitable type to meet modern conditions is indicated as being a form of metal-clad, compound-or Oil-filled, interlocked, draw-out unit for pressures up to 66 kV. A plea is made for the standardization of this type as the best course to adopt for effecting a reduction in switchgear prices. Various schemes of connections for central stations and substations are considered, and the advantages and dis-advantages of different arrangements recorded. A number of typical installations are shown for super-power stations, and particularly super-tension layouts for indoor and out-door service. The working principles of oil circuit breakers are considered, together with the various factors which affect breaking capacity.