What is the gap between two electrodes in oil testing kit?
Maintain 2.5 mm gap between they both electrode sphere. They sphere are connected to the high voltage winding of high voltage transformer.
On what factors breakdown voltage depends?
Breakdown voltage varies with the material composition, shape of an object, and the length of material between the electrical contacts.
What are the causes of reduction in dielectric strength of transformer oil?
The dielectric strength may be drastically reduced by water supply or increased amount of foreign particles. Pure transformer oil is usually free from water and mechanical impurities and its breakdown voltage is greater than 60 KV(kilowatt).
Which is having higher breakdown strength?
High vacuum has the highest breakdown strength followed by thin homogeneous solids and then liquids.
How do you calculate breakdown strength of transformer oil?
“Breakdown Voltage” (BDV) is measured by observing the voltage that is required to jump a spark between two electrodes immersed in the oil separated by a specific gap or distance. Also known as the sparking strength, the higher the voltage required to jump the spark, the higher the BDV will be in the oil.
What is the breakdown voltage test for transformer oil?
The breakdown voltage test is to determine the quality of the insulation properties of the transformer oil. The test itself is conducted by ramping up a voltage, at typically 2kV per second, until the oil breaks down causing an arc between the test electrodes. Typically, the test is conducted 5 times and the average RMS voltage is taken.
What are the factors affecting the breakdown voltage of a transformer?
Breakdown voltage is affected by several factors, such as moisture, particles, acidity, and pressure. Dielectric strength of transformer oil is mainly determined by the presence of fiber and water, so the mechanical impurities and water in such oils must be completely absent. The dielectric strength of the oil decreases with time.
What is the cause of dielectric loss in transformer oil?
Increasing the dielectric loss in insulating oils occurs due to: Asphaltic-resinous substances (form a colloidal solution in oil) Acids (only affected under heating, not at room temperature) Dissolving paints in the transformer oil, that usually lead to sharp increase of acid number.
What happens if moisture is present in transformer?
The presence of moisture in a transformer is very harmful. It decreases the dielectric strength of oil and other insulating material such as winding insulation, paper, etc. significantly. It may be remembered that the presence of only 0.06\% of the water will reduce the dielectric strength of oil to about one half..