Refurbished transformer 800 kVa. who has had experience?

[Sergei Slovenija]

What is the rebuild of old transformers, besides painting and electrical testing? Oil change, insulators, other? What must be done and done without fail.

 

[Dave-sparks]

Inspection and testing should be carried out first to establish what further work is required for a full refurbishment.

An oil change would be fairly standard, anything else will be dependant on what is found under inspection.

 

[Matrixx]

visual inspection, check for loose connections or damage to the windings, oil change, winding resistance checks, tap changer checks, hi pot checks to test the insulation, the resistance check and the insulation tests will reveal any potential faults.
then possibly a load test to check to for weak links. most of the tests will be clearly defined by the regulations in your country.
At 800kVA you will need some expensive test gear.

 

[Sergei Slovenija]

I will reformulate the question. I am considering purchasing a transformer from a specialist rebuild company. There are many offers. What level of work should be carried out on the rebuild of the transformer and who has come across such repaired transformers in practice.

 

[Misterg]

What level of work should be carried out on the rebuild of the transformer and who has come across such repaired transformers in practice.

In a previous employment, a number of 1MVA PCB oil filled transformers were replaced, some with "refurbished" air cooled ones. I doubt that the "refurbished" transformers had anything done other than cleaning the dust off and an insulation test.

 

[Barking Mat]

Why do you need such a huge transformer ?

Does you local electricity supplier not provide this service ?

Are we talking 33,000 volts to 415 ?

What's it for ?

 

[Sergei Slovenija]

Why do you need such a huge transformer ?

Does you local electricity supplier not provide this service ?

Are we talking 33,000 volts to 415 ?

What's it for ?

I don't want to pay the tariff of 0.70 euros per kW. Connecting your own transformer will make it possible to conclude a profitable contract for the supply of electricity, directly from the sales company. According to the conditions for connecting to high voltage (this is an underground cable), we need to supply a 660 kVA transformer, no less. Today, the electrician estimated our consumption, a 660 transformer is enough for us. To the question of why - because we consume a lot and will consume even more electricity.

...two motors of 250 kWh and they are working hard with a full load. And a lot of small ones, 80, 50 and so on.

 

[Sergei Slovenija]

In a previous employment, a number of 1MVA PCB oil filled transformers were replaced, some with "refurbished" air cooled ones. I doubt that the "refurbished" transformers had anything done other than cleaning the dust off and an insulation test.

We asked the Germans what they did with transformers, 5 companies from the first page of the search. I googled the list of what can be replaced during a major overhaul and it impressed me. Of course, everyone gives a guarantee and a certified test report.