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Transformer oil quality characteristics

The oil used in transformers is a product of a petroleum oil refinery obtained by distillation using phenol, acid and hydrocracking.

Over time, under the influence of an electromagnetic field, air, high temperatures and interaction with transformer windings, which also deteriorate in time, the oil loses its dialectic strengths and becomes not appropriate for usage.

For safe operation of the transformer and prolonging its service life, the oil must comply with certain criteria:

– high heat dissipation and heat capacity;

– low viscosity;

– dialectical strength;

–  acids and various impurities absence.

The purity of the oil is one of the most important criteria for ensuring uninterrupted transformer operation.

The oil coming in the transformer must not contain more than 0.001% water for airtight systems and not more than 0.0025% for non-airtight ones.

The content of solid matters match the requirements of purity class 11, for transformers up to 220 kV and class 9 for transformer operating at different voltages.

Due to the increasing oil temperature during the transformer operation, it is important to know the type of oil, its ignition and flash points.

Temperature when oil vapors start to ignite on contact with the flame is called a flash point. For regular oils, the temperature of a flash point is between 130°C and 170°C, and for arctic oils between 90°C and 115°C.

Ignition point – this is the temperature at which oil ignites on contact with air. This temperature range is from +300°C to 400°C.

Even a small amount of air entering the transformer causes oil oxidation. Therefore, it is necessary to monitor the level of air concentration in the oil, at a pressure of 1 kg.m2, it must not achieve the coefficient of 11%.

Due to the presence of solid particles on the inner surface of the transformer, for its normal operation a simple oil change is not enough. Since new oil comes to contaminated transformer environment it is rapidly accumulates all the contaminates. It is worth paying attention to online regeneration processes, which help to restore the characteristics of waste oil to the required standards.

To solve such problems, GlobeCore company recommends CMM-R – mineral oil regeneration equipment. Units allow regenerating of heavily contaminated oil removing solid particles, water, degassing and brighten. Such oil will have the same characteristics as new. Moreover, since the oil will be regenerated, the need to dispose of it disappears, what saves significant amount of money. Such regeneration equipment recoup after several months of work. To many advantages mentioned before, we can add environmental friendliness and low energy consumption, which are also highly important.


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