Silicone oil purification is an important process that takes place during the maintenance of transformers, for which fire safety is a crucial factor.
Silicone oils advantages
Synthetic silicone transformer oils appeared first in the transformer maintenance market in the 70s of the last century as one of the alternatives to polychlorinated biphenyls, which were classified as carcinogenic pollutants.
At that time the expansion of silicone transformer oils was facilitated by a high flash point and a tendency to self-extinguish, which distinguished them in terms of fire safety, as well as resistance to oxidation and thermal degradation. Thanks to these advantages, silicone transformer oils have found theirs use in transformers located in residential areas and indoors, in oil and gas plants, in industries that work with flammable substances, in trains and wind turbines, that is, places where fire safety is a decisive factor.
Risk factors for the quality of silicone oils
However the reliable functioning of such transformers depends on maintaining the physical, electrical and chemical properties of silicone transformer oils also. For example, in high humidity conditions and at 25 degrees Celsius, silicone transformer oils can absorb moisture up to a value of 250 ppm by mass. High water content reduces the resistivity and breakdown voltage of silicone transformer oils significantly, increasing the risks of transformer failure and financial losses.
Therefore it is necessary to follow the recommendations for the maintenance of silicone transformer oils. Silicone transformer oils must be treated by filtration and degassing before being used in power transformers. It is also recommended to fill transformers with silicone transformer oil under vacuum.
Silicone oil purification technology
The GlobeCore company has developed a silicone oil purification technology with an output of 1,000 to 17,000 liters per hour, which is implemented in CMM-type machines. The GlobeCore process makes it possible to increase and keep the dielectric strength of silicone oils steady by removing free and dissolved water, dissolved gases and solid impurities. At the outlet of CMM machines the silicone transformer oils purity correspondes to the 16/14/12 purity class according to the ISO 4406 standard, the mass water content does not exceed 10 ppm, and the volume content of gases does not exceed 0.1%. Also CMM silicone oil purifier machines are equipped with a two-stage vacuum system that makes vacuuming transformers and filling them with oil under
It is possible to use CMM machines right in the time of the equipment functioning to keep the silicone oils characteristics steady. In order to determine the moment of oil purification, TOR-5 online monitoring systems are used. They are installed near transformers filled with silicone oil. TOR-5 measure and calculate the transformer important parameters continuously and transfer this data to a special web application. Based on the dynamics of changes in oil parameters online, the date when these parameters will reach undesirable values and silicone oil treatment with the use of GlobeCore technologies will be required is predicted.
It is possible to use CMM silicone oil purifier machines in repair shops, to perform oil treatment from one tank to another or directly in a de-energized or in a live transformer.
By following the link, you can see a custom-made CMM GlobeCore silicone oil purifier machine. Its output is 2,200 litres per-hour. This machine purifies silicone oil from electric train traction transformers in one of locomotive depots of the italian rail operator “Trenitalia”.