Dissolved gas analysis (DGA) is a reliable technique for detecting the presence of incipient fault conditions in oil immersed transformers. In this method the presence of certain key gases is monitored. The various analysis methods are : Rogers ratio, IEC ratio, Doernenburg, Duval triangle, key gas, artificial neural network (ANN) method. In this paper the various DGA methods are evaluated and ...

When a transformer is energized the phenomenon of magnetizing inrush current occurs and causes a pseudo tripping signal to the differential relay which leads to the problem of mal operation or false tripping of the relay. In order to avoid this false tripping of the differential relay and for safe operation of the transformer the distinction of inrush current with internal fault current is very...

This paper proposes a new algorithm for blocking the operation of Indirect Symmetrical Phase Shift Transformer (ISPST) differential relay when subjected to different operating conditions except internal fault condition. The proposed algorithm is amalgamation of Phase angle shift (PAS) threshold and Optimal Radial Basis Function Neural Network (ORBFNN). PAS between source and load side currents ...

Assessment of power transformer conditions has become increasingly important in recent years. As an asset that represents one of the largest investments in a utility’s system, detection of incipient faults in power transformers is crucial. Dissolved gas-in-oil analysis (DGA) is a successful technique to detect these potential faults and it provides wealth of diagnostic information. This project...

Economically transformers constitute one of the largest investments in a Power system. For this reason, transformer condition assessment and management is a high priority task. If a transformer fails, it would have a significant negative impact on revenue and service reliability. Monitoring the state of health of power transformers has traditionally been carried out using laboratory Dissolved G...

The objective of this research is to compute the mechanical stresses in power transformer resulting from the currents more than rated value during its operation. Due to this high fault current, mechanical stresses are produced indifferent directions which may cause the damage of winding insulation. Various techniques have been adopted to analyze the stresses on transformer windings. For the acc...

power system overvoltages due to switching, lightning and other disturbances are the main problem for designers of the power transformers. once some frequencies of the incoming surges match with some of the natural frequencies of transformer winding, the resonance phenomenon is expected in transformer winding. the resonant overvoltages may destroy the insulation between turns and cause to insul...

In order to diagnose transformer fault efficiently and accurately, a dynamic integrated fault diagnosis method based on Bayesian network is proposed in this paper. First, an integrated fault diagnosis model is established based on the causal relationship among abnormal working conditions, failure modes, and failure symptoms of transformers, aimed at obtaining the most possible failure mode. And...