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why need dielectric test for transformer
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What is BDV test for distribution transformer?
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 29Kvis 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
What is difference between breakdown voltage and dielectric strength of transformer?
The dielectric strenght of a transformer represents the maximum voltage permissible to apply across the transformer insulation i.e. between the transformer winding to another part of the transformer, normally the chassis or another winding and without break-down of the insulation ocurring (e.g. arcing). The breakdown voltage of a transformer represents a voltage that exceeds its dielectric strenght and that causes breakdown e.g. arcing across the insulation.
What is dielectric absorption ratio?
This is a test usually used when performing a insulation resistance on a transformer. This test (result) can be optained by deviding the 30 sec reading into the 60 sec reading. This test recognizes the fact that "good" insulation will show a gradually increasing IR after the test voltage is applied.
What is the hermetically sealed transformer?
Hermatically sealed transformer is a transformer design which has no conservator. Here the dielectric insulating fluid in the transformer tank is completely sealed and is in zero contact to the atmosphere. This type of transformer is used in applications where the transformer is to be installed in harsh climatic conditions(smoke,pollution,dusty environment,etc) or user prefers low maintenance transformer. The design avoids air in the transformer tank therby avoiding sludging and oxidation of the dielectric fluid. Hence it would be safe to say that these transformers need no maintenance of the dielectric insulatating fluid(usually Oil). Normally these type of transformers are accommodated by devices that measure heat related volume variations. Gas cushion is used to compensate the volume variation due to heat. Normally the gas is nitrogen. This gas is thermally uncoupled from the dielectric liquid.
Which is another name for dielectric strength test?
ASTM D149 - 09 Standard Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials at Commercial Power Frequencies
How can you test the dielectric strength of oil of transformer?
dielectric strength is tested by transformer dielectric strength oil testing machine. at first, oil which is to be tested is pour near the two electrode. both the electrode should be dipped in oil . then adjust the distance between the electrode .now start the machine.when a sound came from machine then note down the dielectric strength of the oil.
What is BDV test for distribution transformer?
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 29Kvis 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
What is difference between breakdown voltage and dielectric strength of transformer?
The dielectric strenght of a transformer represents the maximum voltage permissible to apply across the transformer insulation i.e. between the transformer winding to another part of the transformer, normally the chassis or another winding and without break-down of the insulation ocurring (e.g. arcing). The breakdown voltage of a transformer represents a voltage that exceeds its dielectric strenght and that causes breakdown e.g. arcing across the insulation.
How do you check transformer oil thermal stability?
An Oil Dielectric Strength Tester is the standard for qualifying Transformer Oil. Thermal Stability would involve heating and then testing. I do not know of a product which controls heat and applies the HV test.
How can you find dielectric strength of oil in transformer?
by spark gaps immersed in the oil sample
What is dielectric absorption ratio?
This is a test usually used when performing a insulation resistance on a transformer. This test (result) can be optained by deviding the 30 sec reading into the 60 sec reading. This test recognizes the fact that "good" insulation will show a gradually increasing IR after the test voltage is applied.
What is the hermetically sealed transformer?
Hermatically sealed transformer is a transformer design which has no conservator. Here the dielectric insulating fluid in the transformer tank is completely sealed and is in zero contact to the atmosphere. This type of transformer is used in applications where the transformer is to be installed in harsh climatic conditions(smoke,pollution,dusty environment,etc) or user prefers low maintenance transformer. The design avoids air in the transformer tank therby avoiding sludging and oxidation of the dielectric fluid. Hence it would be safe to say that these transformers need no maintenance of the dielectric insulatating fluid(usually Oil). Normally these type of transformers are accommodated by devices that measure heat related volume variations. Gas cushion is used to compensate the volume variation due to heat. Normally the gas is nitrogen. This gas is thermally uncoupled from the dielectric liquid.
Which is another name for dielectric strength test?
ASTM D149 - 09 Standard Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials at Commercial Power Frequencies
How will be conduct test on transformer?
Short circuit test and open circuit test are widely used to test the efficiency of the transformer.
What are the purposes of performing no load test for the transformer?
These two tests are performed on a transformer to determine (i) equivalent circuit of transformer(ii)voltage regulation of transformer(iii) efficiency of transformer. The power required for theseOpen Circuit test and Short Circuit test on transformeris equal to the power loss occurring in the transformer.
How often do you need a Dielectric test on bucket trucks?
Annually
Why the open and short ckt test of transformer is needed?
The open/short-circuit test on a transformer isn't 'needed'. It's only used if you want to find out the efficiency of a transformer.
