How is the dielectric strength of transformer oil determined?
To determine dielectric strength, transformer oil is periodically tested by means of an oil punching apparatus. To test the oil sample, transformer oil is poured into a porcelain vessel in which two “disk electrodes,” one of 8mm diameter and one of 25mm diameter, are mounted.
What is dielectric test of transformer oil?
The transformer oil testing device measures and reports the root mean square value of the breakdown voltage. After the transformer oil test is completed, the insulation oil is stirred automatically and the test sequence is performed repeatedly: typically 5 repetitions, depending on the standard.
How do you test dielectric strength?
Data: Dielectric strength is calculated by dividing the breakdown voltage by the thickness of the sample. The data is expressed in Volts/mil.
What should be the reason for low dielectric strength of oil in a transformer?
The dielectric strength of non-degassed transformer oil falls if the pressure drops. Temperature falls or relative humidity of the air may cause the reduction of the dielectric strength or emergence of some water. Such phenomena may be also caused by the ingress of water into the oil blending process.
What is the standard dielectric strength of oil?
The dielectric breakdown voltage is measured by applying a voltage between two electrodes under the oil. New oil should have a minimum dielectric strength of 35 kV by ASTM methods of testing. Identifies various gas ppm levels that are present in transformer insulating oil.
What is BDV test in transformer oil?
BDV test means the Breakdown Voltage Test. This test is performed for verifying the dielectric strength of the oil of the transformer. Dielectric Strength is the maximum capacity to resist the voltage of insulating oil. This test demonstrates the dielectric Strength of Transformer Oil.
What is a good dielectric strength?
The dielectric strength is then calculated by dividing the breakdown voltage by the thickness of the sample. Most plastics have good dielectric strengths in the order of 10 to 30kV/mm.
What oil is in a transformer?
Three basic types of transformer oil used are mineral oil (mostly naphthenic), silicone, and bio-based. Mineral oil based transformer oils dominate the consumption as it has good electrical and cooling properties, and provides cost-effective solution.
Can a transformer oil be tested for dielectric strength?
Oil stored in drums does not retain its original dielectric strength and should be tested and treated before use in electrical equipment. The following tests can be adopted before using the insulating oil. The oil test in which spark occurs and the testing set trips is known as dielectric strength test of transformer oil.
How does a dielectric oil tester work?
The transformer dielectric oil tester set has been specially designed for testing the dielectric breakdown voltage strength of insulating liquids, a very high voltage is passed through it. The failure of the dielectric strength is shown by a spark across two electrodes.
How is breakdown voltage of transformer oil measured?
Breakdown voltage of transformer oil is also known as the dielectric strength of transformer. Breakdown voltage is measure by the keeping two electrode sphere in oil. Both sphere is separate by some distances. test cell is made from transparent glass. Oil which is breakdown voltage is to measure is take into the test cell. Its shown in fig,
How is the dielectric strength of insulating oil tested?
The following tests can be adopted before using the insulating oil. The oil test in which spark occurs and the testing set trips is known as dielectric strength test of transformer oil. This test is performed in the oil testing set.