Properties and deterioration/degradation of transformer oil
The reliable performance of mineral insulating oil in an insulation system depends upon certain basic oil characteristics that can affect the overall performance of the electrical equipment. To accomplish its multiple roles of dielectric, coolant and arc-quencher, the oil needs to possess certain properties, in particular:
- High dielectric strength to withstand the electric stresses imposed in service
- Sufficiently low viscosity so that its ability to circulate and transfer heat is not impaired
- Adequate low-temperature properties down to the lowest temperature expected at the installation site
- Resistance to oxidation to maximize service life
In service, mineral oil degrades due to the conditions of use. In many applications, insulating oil is in contact with air and is therefore subject to oxidation. Elevated temperatures accelerate degradation.
The presence of metals, organo-metallic compounds or both may act as a catalyst for oxidation. Changes in colour, the formation of acidic compounds and, at an advanced stage of oxidation, precipitation of sludge may occur.
Dielectric and, in extreme cases, thermal properties may be impaired.
In addition to oxidation products, many other undesirable contaminants, such as water, solid particles and oil-soluble polar compounds can accumulate in the oil during service and affect its electrical properties. Testing and analysis of the transformer oil gives us the assessment of oil as well as transformer condition in its running state, enabling us to take better preventive actions and avoid failures / breakdowns
Hence this oil must be periodically tested to ascertain its basic electrical properties, and make sure it is suitable for further use or initiate necessary actions like filtration/regeneration. Transformer Oil is not only subject to its own degradation but is also a carrier of gasses emanated during arcing or flashovers between paper and winding insulations.
Oil and other insulating liquids suffer from electrical and mechanical stresses while a transformer is in operation. In addition, there are contaminations caused due to chemical interactions with windings and other solid insulations, catalysed by high operating temperature. As a result, the original chemical properties of transformer oil changes gradually, rendering it ineffective for its intended purpose after many years. Transformer Oil Testing and Analysis provides important information regarding any such incipient faults, without the need to pull down the equipment from its running condition. We are India’s leading private laboratory for Transformer Oil testing as per ISO/IEC 17025:2017
Our next project is providing emergency on site transformer oil testing services with our NABL accredited Mobile Lab.
