[NTYNUT (OP)]

Hello
how to do maintenance of 3 phase transformer

[alancalverd]

Read the instruction book.

[NTYNUT (OP)]

Hello
where to get instruction book

[alancalverd]

From the manufacturer. It should be delivered with the transformer.

[evan_au]

how to do maintenance of a 3 phase transformer?

Nearby lightning strikes can cause a temporary electrical overload of a transformer. This may cause a breakdown of the insulation between windings (internal arcing), which will waste energy, increase temperature and eventually cause greater problems in the transformer.

Most 3-phase transformers use oil as an insulator and coolant. So routine preventative maintenance involves checking the oil level (to detect leaks) and checking the oil chemistry (to detect water entry and to detect any electrical arcing). Insulators should be checked visually for mechanical damage (eg from hail).

Other checks include clearing dust that may be blocking the cooling vents, and (on larger models) checking that the cooling fans are still working. Buildup of dust or salt spray on the insulators may cause external arcing, which may interfere with radio communications; turn off the power before cleaning the insulators!

A direct lightning strike can cause serious electrical breakdown inside the transformer, drawing excessive current and blowing the fuse. In this case, the transformer must be replaced, and returned to a workshop to remove the oil and repair the failed windings. (I did a few of these during my industry experience...)

Provided transformers are used within their current and voltage ratings, and not overheated, they should last many years.

[NTYNUT (OP)]

hello
Which oil is used for cooling transformer

[Bored chemist]

hello
Which oil is used for cooling transformer

transformer oil
https://en.wikipedia.org/wiki/Transformer_oil
WHy do you not search for  these things yourself?

[NTYNUT (OP)]

what is name of it

[NTYNUT (OP)]

what is magnetic balance test in transformer

[Bored chemist]

what is name of it

Transformer oil is called transformer oil.

[NTYNUT (OP)]

hello
how it is made

[evan_au]

what is a magnetic balance test in transformer?

It is a way of detecting a short circuit in the windings without actually disassembling the transformer.

However, it requires that the transformer be disconnected from the power supply and from the load while the test is being run.

So you need an alternative power supply for the load while the transformer test is underway.
Or just you could just schedule the test at an agreed time, and shut down the load in a controlled way before the test is started; restart the load once the test is finished.
see: https://www.electrotechnik.net/2010/08/magnetic-balance-test-on-transformers.html