Risk prevention for HV transformers: Beyond the health index

An innovative tool to prevent the negative consequences of unexpected failure of HV transformers may be based on the risk evaluation. This risk is formed by three partial components, which are: causes of failure, probability that a failure may provoke a damage and type and entity of damages (magnitude). This approach may be very useful for supporting decisions and addressing periodical investments of electrical operators and utilities having in service HV transformers. One of the more important parameter forming the total risk is the Health Index (HI) of the transformers which is normally based on periodical inspection of the units. HI is related with the capability of transformer to withstand to a cause of failure. The present paper described as the application of this practice, able to evaluate the Health Index, has allowed to prevent a possible unexpected failure of a HV transformer, avoiding negative impacts to electric system, environment and operators.