Transformer Oil Purifier

Using a transformer oil purifier that can help to ensure the cleanliness of the transformer oil, and extend the useful life of transformers to extends the highest efficiency of transformers. Transformer oil purifier, also known as transformer oil filtration machine, vacuum purification system, transformer oil dehydration machine.

The transformer oil comes into contact with more air and metal pipes in an environment that is heated and electrically hit. These environments contain water and a large number of solid impurities, and the transformer oil will be dirty in such an environment. It is necessary to process the dirty transformer oil in time, otherwise, it will affect the performance of the transformer oil to shorten the life of the transformer.


The transformer oil purifier of YUNENG can achieve transformer oil thoroughly dehydrated and remove fine toner. Restore transformer oil to return to raw performance. We have a variety of transformer oil purifiers to choose from, for example, a small online on-Load tap changer (OLTC) transformer oil purifier machine, intelligent transformer oil purifier. Each type of oil purifier has its own features, which you can choose from in your own needs.

Why Transformer Oil Purifier is Required?

In most cases, the quality of the transformer oil plays a key role in the efficient and long-lasting use of transformers. Unfortunately, With the long time use of transformers, the quality of the transformer oil will decrease. The liquid deterioration in the transformer may be caused by pollution, electric stress and oxidation.


The first is water pollution. In this case, this moisture or water is present in transformer oil in a micro carbon transition (referred to as emulsified water), or sometimes only some of the free water (referred to as demulsified water) at the bottom of the device.


Second, too much contact with air and water will also affect the insulation performance of transformers oil. During the operation of the transformer, the higher temperature operating environment will also speed up the oxidation speed of the transformer oil. In order to minimize oxidation, oxygen must be eliminated from the transformer as much as possible.


By purification or centrifugation, water pollution can be easily solved. However, emulsion water needs to be solved using vacuum dehydration. Therefore,  in addition to maintaining the components of the transformer regularly. At the same time, it is also necessary to maintain moisture at a lower level using a transformer oil purifier through a vacuum dehydration process.


By preventing transformer oil deterioration, it can significantly improve the life of the transformer.


Why transformer oil purifier is required



How Does the Transformer Oil Purification Machine Work?

The process of transformer oil purification is mainly to remove gas, moisture and sludge in insulating oil. It mainly involves three steps in total:


  1. Risingoil temperature
  2. Remove dirt and impurities in oil
  3. Dehydration and degassing of transformer oil


Step 1: The oil temperature is increased to 65℃ by the transformer oil purifier, to produce latent heat to isolate the gas and moisture. Due to the decrease in oil viscosity, the heating oil will make it easier to filter.


Step 2: By filter candles or centrifuging action to clear the clay and dirt from insulating oil. Use classical edge filter or depth type filter can filter transformer oil by filter candles. And centrifuging action is to make the oil continuously centrifuge. After the centrifugation is separated, the dust particles settle down at the lower end, and then the oil can be filtered from the top.


Step 3: Removed impurities transformer oil is removed into the degasser. Due to the difference in oil and water boiling point, both compounds were separated, and the oil was filtered off with the help of strong centrifugation.


transformer oil purifier flow chart



Typical Transformer Oil Results Before and After Purification

Condition Test Methods Before regeneration After regeneration
Appearance Visual Cloudy brown Clear and transparent
Acid number, mg КОН/g IEC 296; ASTM D-664 0.63 0.01
Corrosive sulfur ISO 5662; ASTM D-1275 Present None
Moisture content, ppm IEC 733; ASTM D-1533 170 5
Breakdown voltage, kV IEC 156; ASTM D-1816 11 73
Dielectric loss tangent at 90ºС IEC 247; ASTM D-924 4 0.001
Surface tension, mН/m, at 25ºС ISO 6295; ASTM D-2285 22 45
Mechanical contaminants size, micron   50 5
Oxidation stability: mg КОН/g IEC 1125А; IEC 1125B; IP-307 0.2



The Structure of YUNENG Transformer Oil Purifier:

  • Dehydration (degassing) system
  • Filtering system
  • Oil heating system
  • Control panel
  • Vacuum pump, Roots pump, screw pump
  • Cooling system and condensing system
  • Automatic control and protection system


Filter transformer oil has a longer life, better performance. It can protect the transformer and its paper insulating layers, extend the service life of the transformer, and ensure the least downtime repair time.



YUNENG Can Provide:

  • Complete oil purification solution
  • A complete packaging process, just make simple preparations
  • More oil purifier parts (suitable for road trailers, casters, etc.)
  • Multi-function, the oil purifier of multiple tasks can be implemented.



Packaging & Shipping

To be packed in an iron case or wooden case(s) for long-distance (ocean/air) transportation.



In addition to the transformer oil purifier, the YUNENG can also be provided: online oil moisture tester, flow meter, oil regeneration system, dielectric strength tester, hydraulic oil purifier, etc.


By 2020, we have sold more than 15,000 YUNENG branded oil purifiers, widely used in electric, metallurgy, petrochemical, machinery, military, railway, light industry and other industries. If you have any questions or needs about oil purifiers, please feel free to contact us.

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