Transformer insulating oil undergoes a series of changes while being used repeatedly for many operations. Constant use adds many impurities and arcing forms carbon and other gases few of which get dissolves in the oil leading to oil deterioration. Repeated use of the transformer insulating oil in combination with moisture accumulation challenges its fitness and draws attention on the need for a regeneration system.
Sedimentation, centrifugation and filtration are few methods with which impurities are removed in oil regeneration system. Contaminated particles that settle down are removed through sedimentation. Oil and water are separated through layers in centrifugation and filtration separates particles based on their size. Besides these methods, water soluble acids are removed by drywashing.
Oil deterioration occurs when air gradually leaks inside the transformer and the transformer insulating oil comes in contact with water and oxygen. Besides, high temperature and presence of other materials enhance oxidation in the oil and facilitate cracking of the oil’s hydrocarbons.
Subsequently acid and sludge are formed and accelerate oil deterioration besides attacking the oil’s insulating properties. The electrical and chemical attributes decay as time progresses. Timely maintenance of transformer insulating oil through regeneration system can avert oil deterioration and let the apparatus function effectually.
When the oil gets polluted, the viscosity of the transformer insulating oil is affected which in turn hits the cooling attributes of the oil. Such reduction in cooling affects the winding temperature and trips WTI and OTI relays which operate alarm and cooler control of the equipment. It should be noted that transformer operates on thermal imaging.
Besides, breakdown voltage or BDV has an important say in the quality of the oil. Oil deterioration is highlighted in reduced BDV value and low insulation is evident.
Oil regeneration system is important because oil deterioration is inevitable in constant and repeated use. Such oil deterioration occurs due to constant change in breakdown voltage, moisture, acidity, sludge, flash point, pour point, sediments, sludge, dielectric dissipation factor, density and viscosity.
Oil regeneration system employed onsite when the oil is loaded in the transformer. The tangent of the insulating oil, reduction in acidity, proper interfacial tension and dielectric strength, mitigated moisture and removal of particles are done so that the oil is restored to its original status.
Regeneration system is also done offsite where oil in the barrels are treated for removal of pollutants.
The regeneration system comprises of the flow of transformer insulating oil in columns which contain adsorbents. The contaminated elements which cause ageing are absorbed by these adsorbents, which include Fullers Earth and bleaching clay to name a few.
These adsorbents can be reactivated even after they reach saturation point and they remove the ageing particles in an environment friendly way.
On a concluding note, regeneration system can be chosen based on the nature of oil deterioration. Besides removal of contaminants, transformer oil regeneration system has evolved as effectual waste management and sustainability of the equipment as well as environmental factors. Used oils are regenerated to the standards of unused and new oils with focus on oxidation stability to guarantee hassle free operations of the transformer
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