Short Circuit Test : Power Transformer

Yes it should be a type test only.or may be you can choose some frequency.

but calculation can not replace Actual test, it is the only method to validate product design.

All power transforms need to be tested on an individual basis.

However, these tests are usually done at 5% or less of the rated Voltage.

Regards,
Sapper

At the end its individuals choice how much he want to test his products. But ultimately its going to be paid by buyer.

For a 50MVA transformer, Even if he test it at 5% of rated voltage its going to consume 25000KVA,Short circuit test is long duration test and has to be conducted for the period of till the winding temp reaches to its max limit.

I believe for this size of transformer its going to take AtLeast 24Hrs to reach on max time.

So its going to consume 25000x24 = 600000 Units of electricity

Thats about 2.5Mn Rupee. thats about USD 50000.

Can a manufacturer afford this much on each transformer?

Where as its not required on individual basis if -

1 product validation at the time of design and development is done on the basis of min-max analysis.

2 You have a good incoming inspection plan that check all the controlling parameters of all raw materials.For example Resistivity for coper wire and BH curve/eddy and hysteresis losses etc for lamination steel in this case.

3 You have good control on process.

4 You have good outgoing product inspection that have all those parameter which are easy and inexpensive yet can tell the health of product.

Even if I am not satisfied with this I will make a plan that give the provision of testing short circuit test at the batch change of incoming materials like steel and coper.

I agree that this could be an expensive process.

However, depending on the application, the penalties for a failed unit\installation and the damage done at failure could Very easily out-weigh the $50,000USD.

One contractual example supports a client where the penalties look like the following: -

• $20,000AUD for the Failure
• $20,000AUD for every hour of downtime
• Calculated losses due to lost earnings.

This particular client churns approx $1mUSD per hour

The cost for the test is not really significant at this point and yes this is a real example.

For smaller transforms 500kVA or less, I would agree that for the majority of cases batch testing would be acceptable as a minimum.

Type testing still not good enough, especially without the controls you described.

Regards,
Sapper.