Looseness Identification of Stator End Windings of Induction Motor by Modal Test

Insulation failure is considered as major problem in large induction machine which usually occurs due to continuous operation of machine. These need to continuously monitor to protect stator windings of induction machine. Vibrations in stator end winding have a direct bearing on the life of rotating machines which is widely used in industries. Experimental analyses in term of modal analysis to ascertain the stator winding looseness are frequently carried out and vibration related issues are cleared up. Stator end winding problems of large induction motor can be identified by different methods like experimental analysis known as modal analysis or bump test and analytical Finite Element Method (FEM) commonly used to minimize the vibrations of large machines. FEM has a lot of limitations in designing and upgrading of the stator end windings. The Bump test is used to determine the experimental values to derive modal parameter by skilled person. This paper gives experimental results of 2, 4 and 6-noded mode to confirms looseness in the stator end winding. Once the identification of looseness in slots of end winding is done and to improve the stiffness of end windings, changes in the structure is carried out to achieve the better performance of machine in future.