What is the Process of Transformer Oil Purification?

Transformers play an important role in the power industry. Transformer oil plays an important role in transformers and can act as a coolant, insulating oil and safety protection device in transformers.

But did you know that using a transformer for many years will cause the transformer oil to mix with impurities and affect the life of the transformer? So how to stop this phenomenon? How to maintain the high quality and cleanliness of transformer oil?

In this article, you will learn how to use a transformer oil purifier to filter transformer oil, the process of transformer oil purification. I believe you can get the answers you need after reading this article.

1. Benefits of transformer oil purification

As mentioned at the beginning of this article, transformer oil plays an important role in transformers. So transformer oil filtration has the following benefits:

  • Improves the insulation properties of oil and therefore the insulation properties of other media such as paper/cellulose insulation
  • Better insulation, longer life, fewer failures
  • Transformer assets have a longer life and a high return on investment
  • Uninterrupted power with fewer transformer failures and faults

In order to obtain good transformer performance, we need oil filtration machine designed and manufactured to standards. At YUNENG, we produce transformer oil purifiers with high standards to achieve good transformer performance.

process of transformer transit

2. How to filter transformer oil

We all know that transformer oil plays a very important role in transformers. However, if impurities (such as dust, soluble harmful gases, etc.) are mixed in the transformer oil, the efficiency of the transformer oil will be reduced, and the life of the transformer will be affected. Dirty transformer oil can also cause transformer damage and safety issues. Therefore, the transformer oil has to be filtered and purified, so that the transformer uses clean, high-quality transformer oil.

So how to purify and filter transformer oil? The following will tell you the answer.

① The first step: oil temperature heating

The first step in the transformer oil purification process is to raise the oil temperature to the required temperature, usually up to 65°C., This temperature helps to generate the latent heat of the oil, which in turn helps to separate water and gas from the oil in the degassing chamber. In addition, the viscosity of the oil droplets contributes to better filtration to some extent. The recommended heater design should consider a heating area of approximately 1 to 2 W / sq.cm. In transformer oil purification plants, the heating system is protected against backlogs and excessive temperatures. The choice of transformer oil purification machine depends on the power and application of the transformer oil. Yuneng’s transformer oil purification machine can withstand high temperatures of 40℃~300℃.

Technical Parametersflowlitre/point50100150200
Work pressureMhapa≤0.35
Heater temperature range40℃-300℃
Work noisedecibel(A≤85
Filtration accuracyMicron≤3
Total powerkilowatt23253034
Oil treatment indexDielectric loss factor(90℃ ≤0.005


② The second step: removes sludge and dirt from transformer oil

Sludge removal by two main methods:

(1) Remove the sludge through the filter.

The use of filter elements in transformer oil purifier machines to filter transformer oil can be further classified as:

  • Filtering with classic edge filters
  • Filtering transformer oil with a deep filter

Both methods of cartridge filtration are common and have certain advantages and disadvantages.

The edge filter system can be cleaned and reused at least three to four times, but cleaning and installing the edge filter requires a lot of time and labor. The system is robust and can handle large amounts of sludge. The edge filter can be cleaned with a stream of back-pressed dry air/nitrogen to remove contaminants. After defrosting, remove the paper stack and dry in the oven / bright sunlight before re-using. This operation requires professional skills and experience.

New trends and technologies in the market are driving transformer oil purification machines to use filter elements instead of edge-type paper stack filters. These cartridges are similar to water filter cartridges and can be selected from a variety of purification ranges, such as 500 microns to 0.5 microns.

The advantage of using these cartridge filters is that there is no moisture storage because the filter media used may not be hygroscopic. Secondly, the filter paper is easy to replace, which saves effort and effort.

inside of a transformer machine

(2) The sludge is removed by centrifugation.

Another method of separating dirt from oil is a centrifugal transformer oil filtration machine. Conventional transformer oil filtration or transformer oil conditioning is often confused with centrifuge oil centrifugation. Transformer oil centrifugation is a different technology that has little effect on improving oil parameters. The centrifuge used to separate the dirt from the transformer oil can be a low-speed centrifuge, and the centrifuge cone can be rotated at high speed without the need for an electric motor.

However, because these centrifuges cannot remove dirt below the 10-micron level, the separation of dirt from oil by such centrifugation is limited. Therefore, a power-driven centrifuge is necessary, which increases the cost of the oil regulator.

The only advantage of the centrifuge is the recurring cost of replacing the filter element. Electric centrifuges can remove water from oil in its free form, but cannot remove dissolved water. Manufacturers of electric centrifuges also generally cannot guarantee the removal of water to levels below 5 ppm.

③ The third step: dehydration and degassing of transformer oil

These processes of transformer oil dehumidification and degassing are performed in the degassing chamber.

Due to the different boiling points of water, gasoline and transformer oil, dissolved water and oil separation or dissolved gas oil separation can be performed under vacuum.

In the process of separating gas from oil, it is important to retain aromatic hydrocarbons to maintain the original properties of the oil.

When the water level in the oil is higher than the saturation of the transformer oil, the oil is observed in free water.

The removal of free water can be done by a power centrifuge or coalescing principle, the latter being more effective and economical in practice.

It can be known from the above steps that the purification process of transformer oil is strict and complicated. And a high standard oil purifier is required for purification.

China Chongqing Yuneng Oil Filter Manufacturing Co., Ltd. is a company specializing in the manufacturer and sale of oil filtration machines. Yuneng and a local well-known university (Chongqing University) develop professional projects on oil purification, water and gas filtration. Many of the products sold by the company have patented technology. They do not destroy the parameters of crude oil and retain the efficiency of the oil. If you have any questions and needs about the oil purifier please feel free to contact us.

Tel: 86-23-63225705

Email: sales@chinaoilpurifier.com

Address: Zone B, Tongxing Industrial Park, Beibei District, Chongqing, China

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