Explosion in Transformers

[Ajay]

What causes Transformer Explosions and how can they be prevented

[Davidson]

Transformer explosions are serious incidents which result in loss of life, serious injury and damage to equipment and downtime.

Transformer explosions are caused when the oil is vaporized due to the high currents caused by a low impedance fault within the transformer such as a short circuit. The vaporized oil creates a sudden rise in pressure. This causes a pressure wave within the transformer oil. This pressure wave bounces off the transformer walls and more waves created. This causes a rapid rise in pressure within the transformer which results in an explosion.

A malfunctioning on-load tap changer in which the contacts are not properly made can be a reason for the low impedance fault. Inter turn short circuits or inter phase short circuits can also cause arcs within the transformer system.

Special protective devices are available which can prevent transformer explosions. These devices have sensors which identify the rise in pressure and immediately activate a vent valve to relieve the pressure. The pressurized fluids are diverted to a separate chamber.

The explosive gases produced due to vaporization are purged by means of an inert gas which is flooded into the transformer from a cylinder. This is necessary to prevent explosion when the transformer is opened.