Electric Transformers

Hi ,

We have 11KV/720V (3 winding secondary) 6 MVA tranformers , with 4 forced cooling draught fans installed at the top ,

regards

Transient

Heat rises. Where do you think they should be?

Please Sir! Can I be pedantic?
Heat doesn't rise... hot air, hot oil etc will rise giving convection currents...but...heat itself...blah blah blah...

Del (scamper off to hide in secret cat nest)

In the real world, clearly detailed in the paid study by the transformer manufacturer or outside consultancy analysing the application in detail.

For a homework question, your answer.

Try asking the manufacturer, they may know.

But as this is a homework question I doubt they'll help.

It depends on the configuration of the radiators on the transformer. The most common locations are on the bottom of the rads to blow air up between the fins, or on the sides to blow air between them. The hottest oil will be at the top of the radiators, and as it cools it flows downward through the fins and back into the main tank at the bottom manifold.

Add a radiator....

http://www.zenithgroupusa.com/default-1.aspx

That's where I'd put them too.

GA

If it's meant to have fans then it will have brackets already installed and if the fans are missing perhaps you need better security.

Yes, mount them at the bottom level or in the middle of tank. If it is your transformer you can mount them wherever you want. If it isn't you transformer, what are you doing messing around with someone else's transformer? The penalties for this type of vandalism can be quite shocking!

Good Luck, Old Salt

I want your credits for doing this!

on side, a popular option for ease of repair and maintenance

On bottom....

and the reason why you use fans is because of..

so where do YOU Vindo, think the fans should go?

In addition to the location of the fans, you might want to take into condsideration whether the fans should SUCK or BLOW.

Some fans are inside...

I spent 12 years designing transformers. There are advantages to placing at the bottom blowing up for smaller shorter transformers or at the top blowing horizontal on larger transformers. The fans always blow on the tube or radiators. The research is done with actual heat run tests and the results are based on economics. This sounds like a homework assignment. Decide on an approach and try to prove it or assume either might work and chart the advantages of both.

If this is an actual transformer, go back to the manufacturer and get a fan package with a new nameplate, fans, wiring package and brackets. Otherwise your insurance company will not cover increasing the load on the transformer.

To properly anser your question there are may other questions that must be answered first:

Is it Oil cooled?

If so; Is the oil pumped or is circulation dependent on natural convection movement?

Or

Is it Air Cooled?

Does the transformer have radiators or just cooling fins?

Where is the transformer mounted? Inside? Outside? Against a wall? Inside a containment structure? In the open? Above ground or below ground?

What is the prevailing wind direction?

Are there any ambient conditions such as water or chemical vapor that will affect the transformer operation and/or ability to transfer heat away from the core?

Are there other pieces of equipment and/or transformers that will affect or be affected by the heat removal process?

Is maintenance cost of high concern?

These are some of the many considerations that must be identified and then addressed by/with the design of what type of cooling fans and where they need to be mounted on the transformer and exhaust direction/rotation.

If this is homework you need to create a detailed list of all dynamics that can affect the performance of the cooling system then design accordingly.

If this is a real world application issue:

You really need to contact the transformer manufacturer, provide them with all of the above details as well as any other critical facts, then invite their technical application group to vist your site to identify anything you may have missed, and lastly; "Follow their recomendations exactly."