Performance evaluation of power transformer under different diagnostic techniques

In an electrical power system, the transformer is one of the most important and efficient machines, and to ensure the continuity of power supply utmost care should be taken for its safe operation. Transformers are robust device but they may fail over time due to old age, poor insulation, deterioration of cellulose as well as oil insulation. In addition, there are several elements that may lead to insulation's premature aging and damages; these may include oxygen, heat and moisture contents. transformer oil provides insulation and cooling inside a machine, however there are various factors which affect the insulation strength and smooth flow of the transformer oil over the period of time, so it is therefore very important to observe some of the specific parameters like electrical (specific resistance, dielectric strength, dielectric dissipation factor or tan delta), chemical (Water content, sludge content, acidity) and physical (viscosity, flash point, pour point) to check the effectiveness of the transformer oil Therefore by keeping in mind the factor of reliability, this work presents three field transformers along with application of different diagnostic methods on their oil sample. At the end of this work, the detailed analysis carried out on the basis of effects of temperature, humidity, and loading. Tests are performed to check the appearance, breakdown voltage, water content, acidity, dielectric dissipation or tan delta Dissolved gas analysis (DGA) and kinematic viscosity of the oil samples, results obtained from these tests are then compared to IEC standards to check the effectiveness of the oil samples.