Funny and Remote Failure Mode of Transformer

On 16th Sept 2008 (Tuesday) a high voltage distribution transformer caught fire in Behrampore town in the state of Orissa in India plunging large areas into darkness for two days (Times of India, dated 17th Sept 2008, Kolkata edition). And how did it fail and what was the reason?

Apparently a hawk flying over the sub-station hit the high voltage electric wire and fell on the 31.5 MVA (Mega Volt Ampere) transformer which instantly burst into flames. Evidently, due to a mechanical fault, the auto-fire protection mechanism of the transformer failed to work and when departmental staff tried to douse the flames with water, the flames rose higher and went out of control. It is interesting to note that the transformer contains 20, 000 liters of oil to keep it cool and act as insulator.

Apparently it seems that it was freak failure mode. But a little amount of careful thinking would show that it is not. The problem reveals a lot of issues and imperfections in the system.

First, why was the mechanical fault of the auto fire protection lying unattended? Simply because no one perhaps monitored whether the protection system is functioning or not. This is called detective maintenance.

Second, why did the departmental staff try to put out the fire with water? Can an electrical fire by put off with water? It means they did the action without any awareness. They simply thought that it is an ordinary case of oil on fire. Even fire on oil should be doused with foam and not water. A gross neglect of training and lack of preparedness.

Third, what about the strength of the transformer? Was it tested for short circuit resistance? It is not supposed to breakdown if the transformer is tested after manufacture. What about analyzing the gas build up within the transformer? What about regular venting off the gas? Was it built into the system? What about regular and simple monitoring of the di-electric strength of the oil and the dissolved gases in the oil? What does it show? No care to monitor the condition of the transformer and no regard to the intial specification of the transformer during purchase.

So, we can conclude that the event not as an freak accident but as a gross neglect of maintenance and reliability thinking that led to the loss of equipment, manpower and loss of power for the consumers. Even if the striking of the hawk appears to be remote, it is not the real cause of the failure. The real cause was human neglect to care for their assets that led to the failure. Reliability and Maintenance pays!

Dibyendu De