The paper describes the materials used for the construction of transformers, and the types and consequences of the resulting losses. It is also explained how losses can be minimized during construction. Loss calculations were made for three characteristic transformer drives: •sine balanced •sine unbalanced •non-sine balanced system. Within the program package "MATLAB" an algorithm was developed and implemented for the optimization of the substation drive in order to minimize the losses of working energy while avoiding frequent switching operations at the substation level. Based on historical consumption data at the substation level and electrical parameters of the transformer, the schedule of optimal switching states was determined.