Using fiber-optic sensors to measure strain in motor stator end windings during operation

A novel technique incorporating fiber optic strain gages has been successfully used to measure the mechanical stresses on large motor stator winding end turns at different operating conditions. The testing was conducted both on high voltage, large horsepower and medium voltage, medium horsepower motors with form wound coils. The goals for this project were to: (1) accurately measure the mechanical stress on the winding end turns and to determine the reliability of bracing system designs with consideration for reduced insulation allowances, and (2) compare the test data with theoretical calculated values obtained from FEA models. In this paper, the new test method is described and certain test results are discussed.