LIFE CYCLE OF TRANSFORMER 110/X KV AND ITS VALUE

In a deregulated environment, power companies are in the constant process of reducing the costs of operating power facilities, with the aim of optimally improving the quality of delivery and the quality of delivered electricity in the customer’s facilities. The energy transformer, as the most significant and valuable part of the transformer station, must be reliable during exploitation. Bearing in mind the high value of the 110/x kV transformer, which as a case was specially treated in this paper, special attention is now being paid to the research of new approaches and techniques for maintenance, assessment of the condition of the transformer, assessment of its life as an element whose substitution takes a long time. Its unexpected outage causes long-term interruptions in the supply of electricity, so by monitoring the condition, it is possible to prevent expensive and unexpected outages of energy transformers, which are sometimes catastrophic. Existing methods for assessing the lifetime of transformers take into account physical, chemical, electrical characteristics and experimental measurements. One of the possible methods, which can help in assessing the condition of the transformer, is the method for calculating the transformer health index, which takes into account the available factors that affect the health of the transformer. This paper focuses on a simplified method of predicting the remaining service life and estimating the fair value of a power transformer. Someone needs a fair value of the transformer, because he is in a position to sell the transformer or buy it with all its good sides and faults. There is no decisively determined procedure, because there are many unknowns that should be available and that are not systematically collected. It does not matter, if two transformers work under the same conditions, how many short circuits one of them had in its operation on the network it supplied. Even for the same number of short circuits in the network, they differ in the power of the short circuit depending on the distance of the short circuit from the transformer itself. The final answer about the condition of the specific transformer 110/35/10.5 kV, 31.5 MVA and its fair value was reached using: • experience, • data on transformer operating conditions, • periodic test reports, • reports on the condition of oil insulation and solid paper insulation, • the influence of driving events in the 10 kV network, • the „Health Index“ (IZ) algorithm used at the „Nikola Tesla“ Institute, • the philosophy of thinking about the fair value of transformers.