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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.
7.Procedure
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%.
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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.
Another Answer:
There are a variety of tests offered by Utility Testing Laboratoies that track dielectric oil quality including:
Dissolved gas
Dielectric strength
Acid number
Color
Interfacial tension
All tests are performed according to ASTM methods. Standard turnaround for sample testing is 2 weeks. Utility Testing Laboratories can be contacted by phone 8:30am-6:00pm (MST) M-F at (801) 458-891 or find them online at http://ut-labs.com/index.html
Wiki User
∙ 14y ago
Wiki User
∙ 9y agoOne type of a test for a transformer is a megger test. This test applies a high DC voltage to the Transformers windings. What it checks for is insulation leakage to ground.
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If a dc voltage of 12v is added to the secondary of step down transformer and rating of transformer is 220 input and 12v output what will be the result from primary of transformer?
A DC voltage added to one side of a transformer has no effect on the other side.
Can you step up or step down the DC voltage by a transformer?
You need alternating current for a transformer, for DC you would have to interrupt the power supply to make it effectively DC pulses.
Can a high voltage transformer be megged with a megger meter?
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.
Does electrical transformer use a DC or AC source?
A transformer is a device to convert high voltage AC to low voltage AC & vice-versa. It works on the principle of induction. Since induction occurs only in an AC supply, a transformer cannot work on DC.. So, it is not possible to convert DC supply to AC using transformer. You would need an inverter to convert DC to AC.
Why transformers are not excited with dc?
by using step-up transformer we can change the voltage in higher level
Why is a high dc voltage applied to a transformer for testing?
A high dc voltage would be applied to test the insulation between the windings.
How do you make ac into DC in a ac transformer?
You can not change AC into DC using a transformer. A transformer changes the voltage levels. To change AC into DC, you would need a rectifier. To change that into smooth DC you need a capaciter and a voltage regulater
Can a constant dc current can induce a steady state voltage in a transformer?
No, the current has to change for a voltage to be induced in the transformer.
If a dc voltage of 12v is added to the secondary of step down transformer and rating of transformer is 220 input and 12v output what will be the result from primary of transformer?
A DC voltage added to one side of a transformer has no effect on the other side.
Can a constant dc current induce a steady state voltage in a transformer?
No. A constant DC current of sufficient magnitude induces smoke in a transformer.
How do you calculate transformer voltage ratio test?
Secondary voltage / primary voltage
In D.C supply the transformer is not connected why?
In a DC power supply a transformer is connected. The only time there would be no transformer used would be if the DC voltage wanted was 120 VDC. The transformer in the power supply is connected to 120 VAC on the primary side and the secondary side of the transformer is connected to either a half wave or a full wave diode bridge. The voltage out of the diode bridge will be the same output voltage potential as the transformer's secondary voltage but it will be a DC (Direct Current) potential.Reading the question in another way, transformers are not connected in a DC circuit. The reason being is that the transformer operates on a collapsing magnetic field. This field induces a voltage into the secondary side of the transformer. Since the DC circuit does not operate on the principle of a collapsing field except when the circuit is opened, the transformer would not operate as a transformer should..
Can you step up or step down the DC voltage by a transformer?
You need alternating current for a transformer, for DC you would have to interrupt the power supply to make it effectively DC pulses.
What is the conditon to connect a DC supply in primary of transformer?
Dc voltage level should not exceed the current carrying capacity of the winding. since winding resistance is very small. We need to be careful in giving the dc voltage to transformer winding.
Can a high voltage transformer be megged with a megger meter?
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 we used ac volt in supply line instead of dc volt?
AC voltage is more sufficient than DC voltage. Moreover, an AC transformer can be developed but DC voltage will make it harder. Without a transformer, we cannot turn the high and low voltaged into each-other.
Does electrical transformer use a DC or AC source?
A transformer is a device to convert high voltage AC to low voltage AC & vice-versa. It works on the principle of induction. Since induction occurs only in an AC supply, a transformer cannot work on DC.. So, it is not possible to convert DC supply to AC using transformer. You would need an inverter to convert DC to AC.
