We have got a requirement to measur 3

[Rwelagedara]

We have got a requirement to measure the winding capacitances of a 4 MVA, 33kV/690V two winding transformer. But we have no idea on what values (of which range) to expect as results of this test or how to analyze the results of this test. I shall be much grateful if you could give us a guidance in this regard.

 

[7anoter4]

In my opinion, what do you need to measure is the dissipation factor [tangent delta, capacitance power factor] as the ratio between equivalent resistance of dielectric losses and capacitance of considered object[ winding turn-to-turn, windings between, winding to tank, bushing ].See-for instance:

http://www.bhdrentals.com/files/pro...cb-100-power-factor-tester-product-manual.pdf

 

[prc]

The limiting values for power factor is given in IEEE C57.152-2013 (earlier 62) Diagnostic site testing-Clause 7.2.1.For new units 0.5 % is the limit and serviceability limit is 1 %. This is the most effective test to find the insulation condition of transformers.Capacitance values may be refereed to original test report and normally variations of more than +-3 % is to be investigated.

 

[unclebob]

A simple Dissipation Factor / Capacitance tester is all you need. This test is a usual test you do on transformers, along with megger, turn ratio and winding resistance. The Capacitance results aren't good or bad, but they should be about the same year after year. A Doble test also gives capacitance values.