By
definition, “Health” is the state of being free from illness or injury.
The human body is made up of different organs and systems, each with its own purpose and function. These have a limited lifespan. A failure of some systems can cause death and some can be treated to recovery to maintain a longer life. Everything in the world has a definite lifespan. It is important to have some indication of the level of health and to monitor the body for any known illness.This concept can clearly be applied to Power Transformers. Just like humans, power transformers have a limited design life which may either be exceeded or diminished depending on how it has been operated. The main structures of the power transformer have different characteristics and materials. The power transformer is made up of smaller components and systems of which failure can affect or diminish the health/life of the transformer.
The life of the power transformer is directly related to the life of the insulating material [McNutt1]. The copper strands of the windings are insulated by Kraft paper insulation and the core is manufactured from sheets of steel that are individually insulated by a thin film of insulating coating, surrounded in oil. All the insulating materials are affected by changes in energy levels that are generally converted into heat in areas of localized hot spots. It is thus important to maintain a healthy state of a power transformer.
References
[McNutt1]
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McNutt,
W. J., “Insulation Thermal Life Considerations for Transformer Loading
Guides,” IEEE Transactions on Power Delivery, Vol. 7, No. 1, pages 392-401,
January 1992
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