Implementation of Six Sigma Program for Lean Manufacturing “To reduce the rework waste in Transformer manufacturing unit by eliminating defect of leakage from bushings in oil filled transformers”

Transformer can be said to be the power source and an important electrical device of power sector which is used to step up or step down the voltages according to the need of user. It works on the phenomenon of Mutual Induction. Oil filled Transformers get the insulation and heat transfer properties form the oil. But ironically the same oil causes one of the major defects of the transformer i.e leakage. Leakages are as old as transformers and have been a challenge to all the manufacturers. It is a highly time consuming and expensive task to arrest the leakages once occurred at the shop flor or at the site. The location for this leakage has been in most cases from the bushings where the cables or busbars are connected to draw or inject power during its use. These bushings are of different types such as porcelain or epoxy cast. This leakage is normally sealed by use of gasket material and tightening of the bushings to block the path of oil from the inside of the transformer to outside. There have been many delays in production lines due to these leakages and the resulting rework and have also caused complaints from site wherein the customer’s plant had interruption of power during the period of rectification. We have selected this problem as a project and solve it by six sigma methodology to achieve first time right sealing of bushing leakage which will eliminate production of defective parts and be a step towards Lean manufacturing in Transformers