How to test the dielectric strength of transformer oil.

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dielectric strength of transformer oil is the ability of transformer oil to withstand a certain amount of charges when subjected to electricity. This test can be done by passing a DC voltage through the substance. And the DC voltage will be varying its volt till the oil reaches its dielectric breakdown.

The dielectric breakdown is the point when the charge subjected to the oil causes the oil to conduct.

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What do I mean transformer oil?

Transformer oil is an insulating oil used by power transformers. The oil serves as an insulator, meaning it doesn’t conduct electricity. Thus insulating oil is gotten from fractional distillation and treatment of crude oil. There are two substances used as transformer insulating oil.

The insulating or transformer oil performs two main functions on our power transformers.

  • It serves as a coolant to the transformer.

The oil prevents excess heat during the operation of the transformer. It dissipates heat from the transformer. On the power transformer, the whole coil of the transformer is immersed in the oil.

  • It severs as an liquid insulation to the power transformer.

it makes the coils of the transformer not conduct to its metallic body or between its coils.

How to measure the dielectric strength of insulating oil.

For us to ascertain the strength of transformer oil, the following procedures should be followed.

Materials needs for the test.

  • Dielectric test set.
  • Connecting probes.
  • Transformer oil.
  • Containers.

The procedures are as follows.

Step 1.

place the dielectric test set, on a workbench. And connect it to the power supply unit. 220/240V.

To make your work neat and avoid hazards, use a well-ventilated room and good workbench.

Testing dielectric strength of transformer oil
Laboratory testing of insulating transformer oil.

Step 2.

Put in the insulting oil( transformer oil) into the container.

Carefulness should be maintained why pouring the liquid into a container. Google class and hand glove should be used why carrying out these functions.

Step 3.

Insert the two connecting probes inside the oil and make the two probes have a distance of 2mm^2 apart from each other inside the container containing oil.

Step 4.

Turn down and regulate the current knob of the dielectric test set to a zero volt. (0V).

Step 5.

Then, turn off the power supply to the dielectric test set, leaving the connecting probe deep inside the oil and 2mm^2 separated apart.

Step 6.

While the two probes are inside the oil, observe clearly as time increases. At a point, there will be a spark inside the liquid. The spark occurs between the two probes inside the transformer oil. At that point, the transformer oil insulator has a breakdown, and current passes between the two probes.

Step 5.

Observe and take the reading at the breakdown voltage. Conduct the practical test three times and take your average. What it means now is that the transformer’s oil will only withstand electrical current at that value before breaking down.

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