Inspections and repairs: Oil Treatment
The treatment of electro-insulation oil is universally a very important activity carried out in the operation of high voltage instrumentation of oil with paper insulation.
Beginning with the treatment of new oil for parameters required by norms which allow for its use in instrumentation following improvement in the parameters of device insulation (mainly transformers) in operation.
The use of vacuum aggregates in order to process oil allows for it to be cleansed, dried and degassed whilst retaining parameters recommended by international standards, normative documents and operational use.
For example, oil taken from a transformer after its final fill, should not contain more than 12ppm of water in the case of transformers with a 400kV voltage rating, and not more than 15ppm for the remainder of group I and II transformers. In addition, it is recommended that the oil in group I transformers should be well degassed, and for transformers of 400kV voltage rating, the total quantity of dissolved gasses in the oil should not exceed 0,5%. Through atmospheric pressure, a volume of about 10% of air is dissolved in oil.
During use, transformer oil becomes aged, impure and contaminated, which causes, amongst other, a substantial presence of water as well as a deterioration of it dielectric properties. In addition, servicing operations carried out on installation in-house, and connected with dielectric viscosity contaminates the transformer and causes the necessity to carry out oil treatment for the purpose of degassing and drying it.
Vacuum aggregates, commonly known as centrifuges, are used for this purpose, which in conditions of higher temperature or lower oil pressure evaporate water and remove gasses dissolved in oil.
In the aggregate, oil is heated to a temperature in which the water boils, after which in order to avoid harmful overheating of heated oil, the oil is put into the vacuum chamber, where the water evaporates in relatively low temperature and harmless for the oil. Brisk evaporation is achieved through dispergation or pulverization of oil in the vacuum. A very high level of pulverized oil is achieved with the help of centrifuge rotor, from which the oil is precipitated in the form of mist which gathers in the centrifuge surround. Oil is then relieved of suspended matter, impurities, contamination and water in the centrifuge, which remains in the centrifuge, as well as dissolved moisture and air which evaporate. Centrifuged and partly dried and vented oil is directed to the storage vacuum in such quantities , that the surface of the oil and the time it is present are sufficient for effectively eliminating the remainder of moisture and air. This process in high vacuum conditions ensures obtaining the right treatment and efficiency of 6000l per hour.
Energo-Complex offers services to be carried out in the scope of oil treatment (new and used) using the vacuum method with the help of the MAS 6000 portable aggregate. We carry out this service at the installation itself - the client's location.
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