overheating problem of the transformer

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theodreth

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hi

i have a 1000kva transformer.the value i read from the thermometer which is on th transformer is 65 centigrates degree. adn it is dangerous value for a transformer.

it is oil cooled transfrmer and i also add 3 fans i mean vantilators to the transformer room 2 taking the air from the room and giving it out and the 3rd is taking air from out and giving it into the room.

after this condition i was able to decrease the temperature to 55.

the point i aim to ask is:

is it normal at an ambient temperature of 33 centigrates.

if is not what can be the reason of overheating?

can it be the lack of the quality of the oil?

what kind of oil do you use?

thanks a lot
 
those are typical temperature rise value for an oil filled transformer 55/65 degree celcius
 
You have already dealt with the ambinet temperature.

Transformers heat primarily due to the load they are supplying. If you want your transformer to operate cooler you need to reduce your load.

Also, it is possible for the transformer cooling raditors to become less effective due conditions like external dirt or internal plugs. Thermography can be used to evaluate the raditors.
 
It's also important that the oil level be high enough that the upper fin ports are fully submerged, or the oil will not circulate.
 
have a look at the transformer's loading capabilities. I have seen transformers that have (for example)

1) a load of 1 MVA for normal cooling
2) a load of 1.2 MVA with fans installed (forced air)

I have seen transformers operating above load because they were installed inside air conditioned vaults.

if the oil is still the original oil that came with the transformer, it is fine. have to check the oil level (maybe there were leaks) or the circulating pump (if it has one).
 
If the temp gauge reads 65 and ambient is 33 you are fine. The transformer will have a temp rise rating on the nameplate, most likely 55 or 65, that is a max rise above ambient. So if your ambient is 33 and your rating is 55 rise the temp limit would be 88 degrees.
 
Test the oil

Test the oil

One thing that hasn't been mentioned is that you should have an oil sample tested to evaluate the condition of the transformer.
Especially if you're pushing the unit into its nameplate rating.
There are many places that would perform the analysis for you.
JM
 
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