Long-term reliability of amorphous alloy wound core distribution transformers

In order to verify long-term reliability of amorphous alloy wound core distribution transformers, accelerated aging tests and field trials used on actual transformers were practised. As for accelerated aging tests, short-circuit tests were added to imitate mechanical stress in operation on a utility's distribution system. As a result, even after the equivalent of 30 years, which was the normal expected transformer's life, the magnetic characteristic was unchanged, so these transformers could be operated. Additionally, two hundred transformers of four kinds were installed on a utility's distribution system to study no-load characteristics. They were equipped with a mechanism to measure load current, background vibration and lightning surge current, so their influence on magnetic characteristic could be inspected. As a result, no remarkable change was seen even after six months.<
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