Exploding transformers fixed in 30 minutes- how?

[thaibeachlovers]

Where I live, I often hear an explosion at a transformer, and the power browns out. Flouro lights already on stay on, but can't switch an unlit flouro on. Even the fan keeps working at reduced revs.

However, it always takes them 30 minutes to have the power back on. How can that be if the transformer explodes? Would take longer to replace the transformer than that, surely.

Thanks.

[IMHO]

Yes, it takes longer than that to replace a transformer - so the answer must be that they fixed something instead

[thaibeachlovers]

Yes, it takes longer than that to replace a transformer - so the answer must be that they fixed something instead

Ah, yes, but WHAT did they fix? When the transformers explode, it sounds like some damage was done.

[Crossy]

It's important to understand that some electrical events particularly on the HV network are of an explosive and often spectacular nature but little actual damage occurs. Transformers, unless they are seriously overloaded don't tend to explode, and when they do it's more than a few hours to fix

We have regular transformer 'explosions', spectacular at night, usually a snake or monkey has gotten between two phases on the HV side, result vaporised snake / monkey, big flash and bang and power off.

Our village does not appear to have auto-retry on the HV breakers so a man has to come on his motorbike, check for any real damage and wind the breaker back in, usually takes a couple of hours.

[trogers]

...result vaporised snake / monkey, big flash and bang and power off.

The transformer didn't explode...something else did...

[wayned]

Transformers have inline fuses installed on the input lines to protect them. They are not internal to the transformer but actually in a lever type fixture on the input line. When they blow, they sometimes "explode". They can be removed and replaced very quickly using a tool on a long pole from the ground!

They are also there so that if the transformer does fail, it can be disconnected from the high voltage input lines so that it can be safely replaced without turning power off to the entire grid.

[thaibeachlovers]

Thank you for the informative explanations.

I look forward to telling them back home about the power outages caused by exploding snakes .

[Crossy]

Thank you for the informative explanations.

I look forward to telling them back home about the power outages caused by exploding snakes .

A couple of years ago I was sitting in the BMCL canteen at the metro depot. Right outside the window a snake (python?) dropped out of a tree straight across all 3 phases of the 25kV 'small power' supply.

He felt nothing on his way to the next world, but a snake shaped wisp of smoke lingered for several seconds after the power went off.

[jdinasia]

Look outside at your power pole. There is probably a white pair of insulators just below the power lines. That is a breaker switch. I have watched them pop outside my condo in BKK numerous times. A crew comes out, climbs a bamboo ladder (scary) and flips the breaker back into position, rarely wearing adequate insulating gloves.

[Rimmer]

Transformers have inline fuses installed on the input lines to protect them. They are not internal to the transformer but actually in a lever type fixture on the input line. When they blow, they sometimes "explode". They can be removed and replaced very quickly using a tool on a long pole from the ground!

They are also there so that if the transformer does fail, it can be disconnected from the high voltage input lines so that it can be safely replaced without turning power off to the entire grid.

Yes this is correct, the fuse under a fault condition drops down from its mount and can easily be identified and quickly replaced by the repair crews with sometimes a bamboo pole with a hook on the end to grab the fuse carrier, more often now I see the poles are made from some composite material which would seem to be safer.

The last time I had one of these fuses blow on my transformer was when a minor bird somehow got between the phases or maybe he pecked the carrier, either way the fuse cleared with a heck of a bang and immediately a phase dropped out, on investigation I found the bird still warm, a smouldering heap at the foot of the pole and next to it, a large part of the blown out fuse which reminded me of a large firework banger that had gone off, smelt about the same as well.

They quickly came and replaced the fuse which of course I had to pay for, I think it was around 400 baht. Interestingly they wanted the blown fuse back, I assume to prove that they had taken one from the stock on their truck.

Its a regular occurance in the country to get snakes between the phases, I was told by the electric crew that they are attracted to the humming. If you look at HT poles you will see a circular net about half way up the pole which is supposed to stop snakes and rats climbing the pole. Doesn't work too good for minor birds though

[Mudcrab]

Transformers have inline fuses installed on the input lines to protect them. They are not internal to the transformer but actually in a lever type fixture on the input line. When they blow, they sometimes "explode". They can be removed and replaced very quickly using a tool on a long pole from the ground!

They are also there so that if the transformer does fail, it can be disconnected from the high voltage input lines so that it can be safely replaced without turning power off to the entire grid.

replace the drop out fuse

[Pacificperson]

Sometimes the snakes can set-up an arcing which can be seen for miles.