A reliable indicator to detect non-adjacent broken rotor bars severity in induction motors

FEM approach for diagnosis of induction machines' non‐adjacent broken rotor bars by short‐time Fourier transform spectrogram

“…It should be noted that in machines like the one under study, the frequency range for harmonics identification should be up to 2.5 kHz in order to discriminate high‐order harmonics [8, 10, 17] and principal slot harmonics [18]. However, the focus of this work will be on the behaviour of the radial flux harmonics [15, 19], which belong to the frequency range depicted in the following spectrograms.…”

“…Many works on the matter of broken bars outline the significance of non‐adjacency and attempt to assess the broken bar fault severity [9, 10]. In [2], the authors provide a detailed analysis of these effects and provide significant evaluation of the broken bar harmonics during the steady state for a two‐pole squirrel cage induction machine.…”

Detection of Nonadjacent Rotor Faults in Induction Motors via Spectral Subtraction and Autocorrelation of Stray Flux Signals

“…However, this method requires the measurement of currents in all three motor phases (in delta configuration) for the later computation of the ZSC, which is not easy in many real industrial applications. In a more recent work, Gyftakis et al [15] proposed a reliable indicator to detect nonadjacent broken bars based on the Filtered Park's/Extended Park's Vector Approach (FPVA/FEPVA). This method relies on monitoring the higher harmonic index of the Park's vector.…”

Search Coil-Based Detection of Nonadjacent Rotor Bar Damage in Squirrel Cage Induction Motors

“…Therefore, they cannot detect non-adjacent broken bars that interact to cancel the electrical asymmetry [6]- [7], [14]- [20]. Since the only reliable means of detecting non-adjacent broken bars in the field is through direct visual inspection of the rotor, alternative test methods for detecting non-adjacent broken bars have been studied in [14]- [16], [19]- [22]. In [14]- [15], [23], it was shown that the 5 th and 7 th space harmonics-induced rotor fault components in the stator current or radial stray flux spectra can serve as reliable indicators of non-adjacent broken bars.…”

“…However, it is shown in this paper that these proposed saturation-related components are not always present. The 2sfs sidebands of the 3 rd harmonics of the zero sequence current [21], and the 2sfs sidebands of the 6 th harmonics of the Park's vector [22] are proposed for detecting non-adjacent broken bars based on empirical observations. However, [21] can only be applied to delta connected motors with current measurement at the motor terminals, and it is difficult to determine the fault threshold [21]- [22].…”