What are the diagnostic methods for broken rotor bars in motors

Update:06-12-2019
Summary:

The fault diagnosis method of the broken rotor bar of t […]

The fault diagnosis method of the broken rotor bar of the motor is as follows:
An analysis method based on the residual voltage of the stator of the motor when it is out of power: The outstanding advantage of this method is that the fault diagnosis of the motor is not affected by the imperfect power supply, and it is tested from the motor itself and is not affected by the load. However, after the motor loses power, the rotor current will quickly decay, so its effect on the residual voltage of the power loss will also quickly decrease, which will affect the signal detection of the residual voltage.
Hilbert transform based on stator current: This method mainly defines the Hilbert transform of the signal on the complex plane (Hilbert mode). By comparing the normal condition of the rotor and the broken condition of the rotor, it is obtained that the stator current signal is It is a circular shape, and the rotor has a circular shape in the case of broken bars. And use the graphic zoom technology to observe, so as to get the diagnosis result of the motor rotor with or without broken bars.
Rotor stripe characteristic frequency extraction based on wavelet ridge: Wavelet transform has adaptive multi-scale frequency division. It can separate multi-frequency component mixed signals according to the frequency band corresponding to the scale, and respectively obtain the amplitude and Phase information. When wavelet ridges are used to extract the instantaneous characteristic frequency of the signal, the initial values ​​of different scales are selected to iterate, and the required time-frequency ridges can be extracted, and the changing curve of rotor fault characteristics during motor startup is given.

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