Failure Statistics and Condition Evaluation for Power Transformer Maintenance

Measurements on partial discharge in on‐site operating power transformer: a case study

“…Electrical power devices being of strategic importance for transmission and distribution system in each country are undoubtedly power transformers according to which the ratio of investment costs to the total value of spending for components for electricity transmission and distribution are of ∼20%. Emergency shutdown of mains or block high power transformer can cause considerable economic losses, which in extreme situations can exceed the value of a new device several times [1,2]. Paying attention to the fact that many transformer units operating in the electro-energetic system already exceeded 30 years of their exploitation age, therefore, the time of their projected work in the near future could be predicted as a period of slow, however gradually more-and-more common failures during their operation.…”

“…Paying attention to the fact that many transformer units operating in the electro-energetic system already exceeded 30 years of their exploitation age, therefore, the time of their projected work in the near future could be predicted as a period of slow, however gradually more-and-more common failures during their operation. The logical outcome of the given state can be an increase in the number of the so-called catastrophic failures of transformers [1,2].…”

“…The most common cause of failure in high power transformers is local weakening of the insulation system, which can be caused by: material defects, thermal deterioration of insulation, fatigue, vibrations, short circuits and/or overvoltage [1,[3][4][5][6][7]. The primary causes for accelerated deterioration of the paper-oil insulation in transformers are thermal phenomena and magnetostrictive vibrations of the core, which lead to gradual depolymerisation of cellulose and development of a local deterioration of electrical resistance in the insulation material used.…”

A renewal-process-based component outage model considering the effects of aging and maintenance

“…The reliability index of an outage model based on a Weibull distribution failure rate is usually obtained from a Monte Carlo simulation. The parameters of the Weibull distribution failure rate for a transformer are listed in Table 1 [25]. We choose a 230/115 kV, 200 MVA transformer as an example.…”

GADS-based loss exposure evaluation of transformers

“…Power transformer outages have been a major concern for the U.S. electric power sector. Increased operating stresses in transformers from load growth may be identified as one of the serious challenges in mitigating transformer outages [1] [2]. Failure of a single unit could result in service interruption and considerable revenue loss, as well as incur replacement and other collateral costs.…”