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