This paper describes interconnection between technical and economical making decision. The reason of this dealing could be different: poor technical condition, change of substation (electrical network) regime, power transformer owner budget deficit and increasing of tariff on electricity. Establishing of recommended practice as well as to give general advice and guidance in economical sector, testing, diagnostic power transformers to establish its conditions, identify problems and provide potential remedies. All in the paper mentioned information gives possibility to make correct technical and economical decision about furthers procedures. It is very actual moment in technical maintenance of expensive electrical equipment, such power transformers. Forecasting is made for all existing and 28 two-transformer virtual perspective 110 kV transformer substations. The perspective transformer substations can appear with irregular growing of load in different districts of state or if the load of existing transformer substations is not enough due to big load compactness in these districts. For each possible transformer substation place in the territory of Latvian republic and in the developed power supply system must be reserved [9]. Taking into account those two strategies: diagnostic (determination of technical condition) and load forecasting in substation points ensures rational disposition of the funds, but connectivity between technical specialists and financial specialists must be co-ordinate, therefore avoid the transformer owner from unnecessary cash expenditure.