Recommended to perform routine tests at least once a year in order to monitor the healthiness of your transformers. Faults can occur at any stage of transformer’s life and evolve rapidly. Testing your transformers on a regular basis will allow you to detect any unforeseen change in the condition of your transformers. Transformer oil purification is a process to remove sludge, dissolved moisture and dissolved gases from the oil. Transformer oil conditioning may also include to some extent improving the acidity of the oil.
A good oil purification system is able to deliver filtered oil with parameters as per the standard specification.
However, this revival of the oil by oil filtration plant to standard oil parameters is based on the quality of unprocessed oil and its initial process. In case the unprocessed oil does not match the standard oil parameters, then the effort of transformer oil filtration is all in vain. Alternate method of regeneration of transformer oil should be adopted in this case.
Transformer oil filtration by vacuum type dehydration and centrifuge type removal of solids and water separation.
Transformer oil conditioning is a stream line oil filtration process of sludge purification, moisture removal and gas removal.
The first step in this serial process is to raise the oil temperature to a desired level, generally upto 65 Deg C. This aids to give the oil latent heat which later aids to dissociate the moisture and gases from oil in the degassing chamber. Additionally the viscosity of the oil drops which aids in better filtration to some extent. Recommended heater design should consider an area of heating of about 1 to 2 W/sq.cm. In the transformer oil purification plant, the heating system is protected against over pressure built up and excess temperature rise.
The second step of transformer oil purification plant is removal of sludge and dirt from the transformer oil.
Two methods have been used for removal of the sludge:
Removal of sludge by filter candles. and/or Removal of sludge by centrifuging action.
Oil Filtration And Circulation (Min 3 Cycle) Cycle As Per IS:1866:2000.
Field testing of Dielectric strength (BDV) of the Transformer Oil should be carried out in accordance with the provisions of IS 6792 & IS 1866 at regular interval during filtration job. The readings must be submitted to EIC for acceptance before stopping the filtration job.
The BDV test shall only be conducted after giving sufficient time for the oil to settle down after stoppage of the filtration process. Min BDV Value after completion of filtration and cooling down of oil should be min 60KV using 2.5mm gap electrode as per IS 6792 & PPM should be less than 20.
Removal of all suspended particles such as dust, rust, scales, colloidal carbon oxidation sludge etc. up to < 1 micron. Degassing and Dehumidification of Transformer Oil under vacuum. Circulation of heated Oil and Filling of treated oil in Transformer tank. De-acidification by evaporation and adsorption method.
Our single stage plants are capable of attaining following oil parameters in 3-4 passes and Two Stage Plants in 1-2 passes.