Early Leakage Detection of SF6 Gas in Gas Insulated Switchgear

The paper deals with an effective method for early detection of leakage and leakage points in SF6. based Gas Insulated Switchgears. SF6 is widely in use since it is most suitable gas accepted for high voltage applications due to excellent dielectric properties, high thermal conductivity, fast arc quenching. The pressure and density inside Gas Insulated Switchgear are dependent upon dielectric properties of SF6. Conventional one-point measurement of gas pressure and density fails to take into account the variations in pressure and density because of non-uniform temperature profile. It is observed that the pressure inside the chamber rises 3 to 4 times of the normal pressure when arcing phenomenon takes place. The rise in pressure makes it easier to detect leakage by taking multiple pressure measurement samples. Conditions similar to that of arcing were simulated and variations in pressure were investigated with four different points of leakage. The results indicate a considerable difference in the profiles due to leakage from the four different points which cannot be detected by conventionally used one-point pressure-temperature-density measurement system. A four-point pressure measurement approach is proposed which analyses the improvement in leakage diagnosis accuracy using Support Vector Machine (SVM) and Multilayer Perceptron algorithms.