In a rural terrain, fragmented economically insignificant farms are becoming less. Big farms predominate over large distances with a considerable consumption of electricity. In towns and villages, the population decreases. At step down substations, two 110 kV transformers is an excess because one of them predominantly is idle. Although with a certain load duration curve, power losses in multi-transformer substation may be less, however, all the same, life cycle cost for multi-transformer substations is more. To provide sufficient for such local power supply reliability, sometimes it is possible reserving the MV secondary side of these transformers from neighboring networks of the same voltage. But for this it is necessary to increase the primary voltage of the distribution network from 20 kV to 33 kV, and among all consumers of the substation supply zone, to identify those who, without much harm, can endure without electricity a couple of hours but in the power system to keep the spare transformer on move. However the option of 33 kV can pay off only by total renovation of transformer’s park of some part or of entire power system