Page 29 - Newsletter

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SAFER DESIGNS FOR TRANSFORMERS TO PREVENT EXPLOSIONS

When an eerie blue glow lit up the sky above New York City last December,
some were disappointed to learn that aliens weren’t involved. The cause

was, in fact, terrestrial: a transformer had exploded at a local power plant.

For the most part, transformers—which help power companies transmit
electricity efficiently by altering voltages—are relatively safe. Fewer than
one percent explode—but those explosions can be deadly, and result in

flying projectiles, toxic fires, or oil spills.

Transformers rupture due to a build up of excess pressure in the tank in
which they are encased, which is usually filled with mineral oil that acts as a
coolant. Contaminants within the oil, the degradation of transformer parts,

and electrical storms can all cause a fault, called an internal arc, that results
in a rapid release of energy.

The internal arc inside the transformer heats up the oil and the oil burns to
create a gas which causes high pressure. Conventional tank designs are not

capable of resisting such high energies which can reach up to 150
megajoules, equivalent to 150 sticks of dynamite. ABB , based in Varennes ,

Canada has been working for over seven years to build a more resilient
transformer tank.

Their solution, described in a paper published 12 June in IEEE Transactions
on Power Delivery, is called TXpand. The idea is startlingly simple: design a
tank that’s flexible enough to deform to absorb all that extra pressure

without rupturing.