Answer Posted / rahul sharma
BDV tests is used to test the dielectric strength of the
transformer.
A new transformer oil shol\uld have at least dielectric
strength of 39 KV as per british standards.
Transformer oil used are normally tested using ASTM D877-82
with the KV strength testing,using 1" electrode spaces 0.1"
apart & test voltage increased at 3000 volts\min until it
breaks down. The avg KV obtained after 8 trails is
considered the oil dielectric strength.
Using this test dielectric strength at 30KV & above is
considered good. Dielectric strength between 23 to 29 KV is
considered usable ,but requires filtering, below 23 KV
transformer oil should be replaced.
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