Transformer Oil Filtration Procedure

How a Transformer Oil Filtration Machine working ?

The Transformer Oil Filtration Machine is a maintenance equipment used for power transformers, switches, capacitors, etc. It mainly filtrates, dewater and degas the transformer oil, greatly improve the characteristics of transformer oil, such as insulating function. After filtration, the breakdown voltage and dielectric strength of transformer oil will be greatly improved, meet the requirements of insulating oil for electrical appliances.

According to the number of vacuum stages, transformer oil filtration machine is divided into Single-Stage Vacuum and Double-stage High Vacuum. Their applications are different, generally, Single-stage vacuum suits for low voltage power transformers, such as below 66KV. While Double-stage High Vacuum suits for high voltage or ultra high voltage power transformers, above 110KV. Besides, Double-stage High Vacuum Transformer Oil Purifier has a higher effiency, and can treat transformer oil with a capacity of 18000 liters/hour maximumly.

The transformer oil filtration procedure is as below:

(PureTech Model DVOP Double-Stage High Vacuum Transformer Oil Filtration Machine Procedure)

1- When the oil filtration machine starts working, the transformer oil that needs to be purified is sucked into the coarse filter under the pressure difference (external atmospheric pressure and internal negative pressure, vacuum pump created vacuum inside the transformer oil filtration plant), and through the coarse filter, large particles of impurities and metal chips are filtered out.

2- Then the transformer oil is heated by the electrical heater to a setting temperature, generally the set temperature is 65℃,aiming to reduce the viscosity of the oil, improve the ability of oil dehydration and degassing, and will not cause oil aging due to overheating. A thermostat is installed in the electrical heater to monitor and control the oil temperature. When the oil temperature exceeds the set temperature or is lower than the set temperature, the thermostat will work to turn on or turn off the heating.

3- Heated transformer oil flows into the degassing chamber where oil dehydration and degassing happens. The specially designed "T" shape vacuum chamber extremely enlarges the evaporation area of transformer oil under vacuum, the transformer oil is sprayed out at a high speed through several small nozzles, and becomes extremely small oil beads, moisture and gases will be separated from oil beads and sucked out by vacuum pump. Under the action of the spray device, the separation process of demulsification, dehydration and degassing has been carried out .

4- The mixed gas formed by vaporized water vapor, light hydrocarbons and other gases passes through the water-gas separation device and the vacuum chamber, and the cooled water enters the drainage device and is discharged. The remaining non-condensable gas is discharged through the vacuum pump.

5- The oil that removes water and gas passes through the oil pump and then enters the fine filter I and fine filter II to filter out the small particulate impurities in the oil, ensure the final impurities contained in transformer oil no bigger than 1 micron.

6- After two stages of fine filters, we get the purified and clean transformer oil. Purified oil sample can be taken from the oil sampling valve.

7- This transformer oil filtration plant can also achieves both external circulation and internal circulation. External circulation: connect the oil inlet and oil outlet to the transformer oil storage drum or transformer oil tank.  Internal circulation: open circulation valve of transformer oil filtration plant, and close the oil inlet/outlet valve, let the transformer oil flows inside the oil filtration plant unit the oil sample is qualified.

Above is the entire transformer oil purification process. In some cases, such as customer requirements or differences in working environment, we also accept custom designs, such as adding an oil inlet pump to realize the function of separate pumping oil and hot oil circulation, adding a vacuum valve to realize the function of using this transformer oil filtration machine for transformer evacuation, etc. If you have special custom requirements, please contact us.