Views: 12 Author: Site Editor Publish Time: 2013-08-02 Origin: Site
On TRANSFORMER OIL BREAK DOWN VOLTAGE test is carried out which is done on field while filling the oil in transformer. This process is also called oil filtration.
1.Take sample from top of Transformer before filtration.
2.The BDV of oil should withstood min 50 KV
3.The gap between the test electrodes sample to be 2.5mm maintained
4.At least 5 sample(top/bottom) should be checked separately while filtration.
5. The samples should withstand 50 kv for 1 min.
5. Take the average of all the samples timings.You will get value.
a.Voltage should be gradually increased from 0.
b. At one point Flash will take place and that point is
termed as Bread down Voltage
The break down characteristics depends upon initial moisture content of transformer & oil. The electrical strength of oil depends upon the water content in transformer & temperature gradient. The electrical strength of oil is reduced if the water content is more than 2%.
There are several standard test, specific components are needed to conduct these tests, although, like a car's motor oil, a visual inspection can determine the amount of oxidation, and broken-down mateial in the oil. See the related links for typical tests.
i would like to add here, regarding tests. we can do various test like dissolved gas analysis(DGA), check for furan compounds- it shows damage to the insulation, etc to check the transformer oil and take various actions.