Power Transformer Oil Testing

Transformer oil testing is one of the important parts for a power transformer. This test will performed when your power transformer cooling system is oil type. Transformer oil in not any ordinary oil. Its use to call transformer oil and it little bit pricey. In this post I will explain everything about this experiment and I will also provide you a live video link that you can understand it very well. So let’s go.

First of all you have to collect the oil sample form an active transformer. But you have to remember one thing that you have to collect the down level of oil. Because all impurity and dusty oil always stay at bottom level. You will know when you need to perform this oil test because manufacturer of the transformer will provide you the operation hour and after reaching the provided operation hour you have to run this experiment.

Related: Power Transformer Troubleshooting

Transformer Oil Testing:

Now collect the dark brown cloudy color of oil from the bottom level drain and this oil indicate the detraction of the oil condition. You have to remember one thing; the testing voltage of the transformer oil tester should be increased gradually.

Now for testing of the transformer oil has two methods. If the oil condition is good then it should withstand 45 KV for one minute in a standard oil testing cup with 4 mm gap between electrodes. Now the testing oil sample is in good condition then it should withstand 25 KW for one minute in a standard oil testing cup with 2.5 mm gap between electrodes.

Transformer Oil Testing Procedure:

1. First check the transformer oil tester is powered up or not. If it’s powered up then stop the power.
2. Then fill up the sample oil in the testing-cup at 90% by removing its cover. Make sure that two electrodes stay 100% bellow from the oil top level.
3. Then use a magnate to remove the metal particle from the oil by putting is through the oil-testing cup.
4. Now covered the cup and run the test for three times. Take the average value as a test result.
5. You can take any method that I mentioned according to your oil sample condition.

Related: Transformer Working Principle, Construction and Types

Acidity of Transformer Oil:

Usually acids are formed when the transformer oil is operational. This formation is rapid at temperature is above 750c. This acid is responsible for corrosive in nature and damage the winding core, main body tanks and others components. It is also responsible for sludge formation. Acidity is used to expressed in terms of number of milligrams of Potassium Hydroxide (KOH) to neutralized the total free amount in one grams of the material (Oil).

Now The Recommended Acidity as Follows.

1. Acidity below at 0.5 mg KOH/gm is permissible, if the oil is satisfactory.
2. Acidity between at 0.5 to 1.00 mg keeps the oil under observation.
3. Acidity above 1 mg/gm means oil discard.

Here is the live video link for a Power Transformer Oil Testing.

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