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Mineral Insulating Oil, Generator Overhauling

6 Key Indications Of Transformer Oil Deterioration

No matter what we do for a living, electricity is all around us, and we would not be able to carry on with our daily tasks without it. A typical difficulty that comes along with managing the electrical power supply is efficiently storing and supplying it to the different sources when needed.

The most common way of combating this issue is through the use of a transformer. What the transformer does is store the electricity and just like its name suggests, transform the electricity from one voltage to another. It is a critical device to have since most of the common items or appliances that are used at home require different voltages.

However, in order for a transformer to work efficiently over a long period, it needs to be maintained accordingly. One way of maintaining it over the long run is to test the transformer oil regularly and treat it when needed. An alternative that some use to the transformer oil is mineral insulating oil.

Not treating the transformer oil regularly results in it not being able to cool the transformer down and can cause severe issues like fire due to overheating. To prevent this, it is vital to be able to spot indications of transformer oil deterioration. Hence, here are 6 signs of transformer oil deteriorating.

1. Dissolved gas oil test

One of the main reasons for the frequent breakdowns of a transformer is because the transformer oil is exposed to too much gas and moisture. This affects how well the transformer oil can keep the transformer cool and insulate heat and electricity.

At the same time, if the dissolved gas oil test reveals high volumes of gas in the transformer oil, it is a sign for you to replace your transformer entirely, before a breakdown occurs.

2. Infra-red scans

This method is similar to how a doctor utilises x-rays to diagnose issues on the inside of one’s body. The infra-red scans expose the spots of the transformer that is at a higher temperature than usual.

This is typically a sign of a weak spot, and it would then be best to replace that particular area.

3. Frequent leaks

Although leaks are a common issue that can be fixed easily, frequent leaks occurring on your transformer is evidence of a larger undetected issue. Hence, leaks are something that you should always be checking out for on your transformer.

A handy tip will be to immediately replace your transformer if you experience frequent leaks, instead of fixing it repeatedly. Likewise, it also applies to other industrial equipment you own; such as a generator.

However, before determining if your generator requires a replacement, you should opt for a generator overhaul to check each part of the equipment thoroughly for any issue. After doing so, you’ll be able to ascertain if it’s a replacement, repair or redesign that your equipment requires.

4. Unusual sounds or strong vibrations

Just like other appliances like a washing machine or toaster, unusual sounds usually are a tell-tale sign of an issue. This is common with cars as well.

If your transformer is making unusual sounds that you did not hear when you just got your transformer, then there is a high chance that it needs a replacement or repair before it gets worse. Strong vibrations when it is working is also a sign of impending issues.

5. Flaking of the transformer’s exterior

This is one sign of transformer oil deterioration that many look past and not take seriously. Such a sign is usually brushed off as a cosmetic defect or a sign of wear and tear over time. However, it is one sign of transformer oil deterioration.

When the transformer oil is deteriorating, it does not cool the transformer as effectively. This leads to the transformer overheating due to extended use, and exterior paint would start cracking and peeling off. Hence, this is one sign that should not be brushed off.

6. The colour of the oil

This sign is a simple one to check routinely. When checking for the colour of the transformer oil, it is key that you ensure that the oil remains the same colour during each routine check.

A sign of transformer oil deterioration is seen when the oil is dark of black. This happens when your transformer takes a hit of electricity and heat. When the oil is dark or black in colour, it reaches a point where the oil is barely cooling the transformer. It is only a matter of time before an overheating occurs.


Be it your transformer or electric motor, the condition of your equipment is key to ensuring the overall performance of your facility or warehouse. Hence, understand when is the right time to seek maintenance, such as electric motor rewinds, switchgear testing, and so on – depending on the type of issue your equipment is facing.