When constructing the structural part of a substation .it is advisable to use light-weight industrial structures and elements (panels ,floors ,etc.) made of bent sections .These elements are pre-made outside the erection zone and are only assembled at site .This considerably cuts the terms and cost of construction. Basic circuitry concepts of substations are chosen when designing a powersupply system of the enterprise .Substations feature primary voltage entrances .transformers and output cable lines or current conductors of secondary voltage .Substations are mounted from equipment and elements described below .The number of possible combinations of equipment and elements is very great .Whenelaborating a substation circuitry ,it is necessary to strive for maximum simplification and minimizing the number of switching devices .Such substations are more reliable and economic .Circuitry is simplified by using automatic reclosure or automatic change over to reserve facility which allows rapid and faultless redundancy of individual elements and using equipment.