Correction of rotor winding fault characteristic for cage motor

The sideband with the frequency of (1-2s)f1 in stator current is the basic characteristic to analyze cage motor rotor winding fault, but for this component more qualitative study is carried out on its existence, very little quantitative study is executed. The cage motor rotor winding fault characteristic is affected by speed fluctuation and load inertia, thus the accuracy of the fault diagnosis is reduced. The fault of rotor winding leads to rotor´s speed fluctuation with double slip frequency, this fluctuation decreases the magnitude of the left sideband, causing the underestimate of fault degree. The degree of this kind of affection is also closely related to the load inertia. Through utilizing the measured value of (1+2s)f1, correction of rotor winding fault characteristic can be performed and the actual value of the fault characteristic can be obtained. This kind correction not only basically eliminates the impact of speed fluctuation on the fault characteristic but also helps to minimize the impact from load inertia, thus it contributes to enhance the accuracy of fault diagnosis of machine´s rotor winding