Role of Hering VPT in transformer oil filtration

Hering VPT, which is known for its German precision offers oil filtration systems since 1909. Besides they also assist clients with training in transformer oil maintenance. Hering EOK series minimize moisture in the fluids and removes gases and volatile acids from the oil. As increasing use of transformers results in additional exposure to voltages and stress, EOK series offers three series of transformer oil filtration plants.

EOK Basic is used for treatment of oil in storage tanks of new transformers. EOK standard is equipped with easy access and has an automatic cleaning process which is beneficial for onsite transformer service and repair. EOK Professional is highly flexible and cleans oil in short span of time.

Oil filtration equipment

Transformer oil filtration system is equipped with oil filters, inlet and outlet pumps, oil heater, vacuum pump and degassing tank. The oil heater evaporates moisture content while the vacuum process gets rid of unwanted gases. The filter system removes the solid contaminants.

Transformer oil filtration

Transfomer oil supports hassle free functioning of transformers, which in turn is the backbone of the power industry. Since most of the transformer failures occur due to contaminated oil, regular maintenance of transformer oil averts replace or repair of the equipment. When abstained from filtration process consequences such as arcing, overheating, corona discharges and decrease in insulating strength of oil, occurs. Hence transformer oils are treated by filtration, drying and degassing.

The transformer oil acts as a coolant and protects the transformer’s windings when voltage goes up and down. It increases resistance between windings and avoids short circuit. The temperature display indicates the condition of the oil inside the transformer thus protecting the apparatus from severe damage.

Transformer oil tests

Besides electric and mechanical stresses that transformer oil is subjected to, the chemical interactions between windings and the high temperature cause contamination. The tests of transformer oil include dissolved gas analysis, Furan analysis, PCB analysis and general electrical and physical tests.

The electrical and physical tests are as follows. The condition of the oil is determined by dielectric strength or breakdown voltage (BDV), water content, neutralization value, interfacial tension, colour and appearance, test for oxidation stability, resistivity, flash point, pour point, viscosity, sludge test and dissolved gas analysis. Filtered oil is pale yellow in colour in contrast to the dark brown colour of contaminated oil.

When any of the above tests does not give the desired value, filtration must be conducted immediately. The filtered oil increases insulation of the oil and that of paper or cellulose insulation material. Filtration enhances longevity and minimizes breakdown of the transformer, which in turn provides better profits as an asset. Lesser breakdown provides uninterrupted power supply.

Transformer oil filtration process

Transformer oil filtration removes sludge, moisture and dissolved gases from the oil. The temperature of the transformer oil is raised to 65 degrees Celsius so that moisture and gases disassociate themselves from the oil. The viscosity of the oil drops and enhances the process.

The sludge in the oil is removed either by filter candles or through centrifugal action. The filter candles could be either edge filters or depth filters. Edge type filters can be cleaned three or four times yet their cleaning process is manual and cumbersome. They hold huge sludge quantity. The filters can be cleaned through reverse pressurized dry air or nitrogen flow which removes dirt. Other cartridges between sizes 500 microns to .5 microns are also available for filtration processes.

Sludge is also removed through centrifugal action. This method can be of slow speed without the need for additional motor to spin at high speed. However, it does not remove dirt below 10 microns. Dehydration and degasification comprise final steps for transformer oil filtration.

Media contact

Company Name: Hering VPT
Contact Person: Detlev Bastek
Email: Send Email
Phone: +49 9831 8834666
Address: D-91550 Dinkelsbuhl,Ernst-Schenk-Str.10
Country: Germany