Power Transformer Oil Testing

Electrical Transformer No Comments

Transformer oil testing is one of the important parts of a power transformer. This test will be performed when your power transformer cooling system is an oil type. Transformer oil is not any ordinary oil. Its use to call transformer oil and it a 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 very well. So let’s go.

First of all, you have to collect the oil sample from 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 the bottom level. You will know when you need to perform this oil test because the manufacturer of the transformer will provide you the operation hour and after reaching the provided operation hour you have to run this experiment.

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 a 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 a 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% below from the oil top level.
3. Then use a magnet 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 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.

The 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 damages the winding core, main body tanks, and other components. It is also responsible for sludge formation. Acidity is used to express in terms of the number of milligrams of Potassium Hydroxide (KOH) to neutralize the total free amount in one gram 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 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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