Untitled3Googling the word ‘transformers’ brings up the Hollywood blockbuster movie about incredible machinery coming to life and saving the world. In reality, a transformer is the heart that pumps electricity at a constant supply, saving the world from darkness, writes ESI Africa editor, Nicolette Pombo-van Zyl.

Eskom’s planned load shedding, implemented to keep 80% of South Africa supplied with electricity during times of crisis, such as when there is an increased demand for electricity and a shortage of generation capacity, means constant switching of circuits, and this contributes to the breakdown of switchgear and transformer assets.

This scenario is not ideal, as in the electricity supply industry the performance of transformers and associated assets is a critical aspect in keeping the delivery of electricity at a constant, and is vital to the operation of industrial plants, commercial enterprises and residential buildings.

However, whilst generation equipment is often blamed for load shedding and outages, unreliability of the distribution networks is often the cause.

Expected service life of transformers

Since the power transformer is one of the most important and expensive items of capital equipment in a distribution network, it is strategic and vitally important to maintain the assets correctly to keep them at optimum performance and extending their service life.

According to Chris Reay, CEO of Engineer Placements and Council Member of the South African Institution of Mechanical Engineering (SAIMechE), it is possible to find units that have been in service for 40 – 50 years, efficiently performing the imperative function of transforming voltages either up or down as required for distribution.

Jan Scholtz, Senior Engineer at Eskom Distribution, confirms that large power transformers (>1MVA) should last between 30 and 40 years. Smaller polemounted power transformers may last 15 to 20 years; and miniature substations on cable networks should have a life span of between 30 and 40 years.

With this in mind, it is vital to note that the transformer will fail if operated above the…

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