When you say BDV you might mean the dielectric strength of transformer oil. A new transformer oil should have at lest a dielectric strength of 39 KV. from a British standard.Transformer oils used are normally tested using ASTM D877-82 with the KV strength tester using 1" electrodes spaced 0.1" apart and the test voltage increased at 3,000 volts/min until it breaks down. The average Kv obtained after 8 trials is considered the Oil dielectric strength.
Using this test method,dielectric strength at 30 kv and above is considered good. Dielectric strength between 23 to 29Kv
is considered usable, but requires filtering. Below 23 kv, the transformer oil should be replaced.
Another method ASTM D18747-82 uses the small radius electrodes but spaced only .o4 inches. The test voltage is 500volts/min and increased until breakdown. The dielectric strength is still the average Kv obtained in 8 trials. The dielectric strength of 28-29Kv is considered good. Below 28 kv, the transformer oil is usable but requires filtering. The latter method is considered a better test method
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why need dielectric test for transformer
in isolation transformer earthing is not provide on secondary side but in ordinary transformer neutral of secondary side is earthedAnswerAn isolation transformer is a 1:1 ratio transformer; its function is to electrically isolate the secondary side from the primary side without changing the voltage. An example of an isolation transformer is the one used in a shaver socket.A distribution transformer is a step-down transformer, used within the electricity network's distribution system. An example of distribution transformer is a pole-mounted transformer, supplying low voltage to residences.(Of course, all mutual transformers provide electrical isolation between primary and secondary.)
Short circuit test and open circuit test are widely used to test the efficiency of the transformer.
A '33-kV transformer' is a three-phase primary-distribution transformer, used in the UK's electricity system to step down the 33-kV primary-distribution voltage to the 11-kV secondary-distribution voltage -the lowest voltage used in the high-voltage distribution system. These transformers are categorised as 'power transformers', and are located in what are termed 'primary substations'.
Blowdown Valves In case of Transformer oil the meaning of BDV is break down voltage. It refers to the one of the tests of the oil.
press the bulb lens
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A distribution transformer IS the term used to describe the utility transformer which supplies a residence.
No. A megger's output voltage is not high enough to test the insulation of a high-voltage transformer if, by 'high-voltage transformer ', you mean a distribution transformer or power transformer. Instead, a high-voltage test set or 'pressure tester' (e.g. a 'HiPot' tester) must be used, as these produce far higher voltages.
why need dielectric test for transformer
The maximum efficiency condition in distribution transformer is said to be occurred when iron loss = copper loss
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in isolation transformer earthing is not provide on secondary side but in ordinary transformer neutral of secondary side is earthedAnswerAn isolation transformer is a 1:1 ratio transformer; its function is to electrically isolate the secondary side from the primary side without changing the voltage. An example of an isolation transformer is the one used in a shaver socket.A distribution transformer is a step-down transformer, used within the electricity network's distribution system. An example of distribution transformer is a pole-mounted transformer, supplying low voltage to residences.(Of course, all mutual transformers provide electrical isolation between primary and secondary.)
Short circuit test and open circuit test are widely used to test the efficiency of the transformer.
A transmission transformer steps the voltage up to a very high value so electricity can travel long distances on transmission lines from the power plant to a city or area with low loss. A distribution transformer steps the high voltage back down to a level that can be used for local distribution and use by businesses and homes.
Transformers are inherently bidirectional.