Broken Rotor Bars In Induction Motors Research Articles

A New Criterion for the Quantification of Broken Rotor Bars in Induction Motors

This paper addresses itself to evaluate quantitatively the severity of broken rotor bar (BRB) fault, i.e., the number of BRBs in induction motors. Sideband components are induced in stator current if BRB fault is present and commonly used for diagnosis purposes. Filippetti criterion has been proposed and developed in the literature to quantify the severity of BRB fault by using sideband components, however, with unsatisfactory universality/accuracy. This paper briefly analyzes Filippetti criterion, and mathematically derives a new criterion for the quantification of BRBs, based on the electromagnetic mechanism of sideband components. Comparing to Filippetti criterion, the universality and accuracy of the new criterion are both improved. Moreover, the new criterion includes the influence from the interbar currents associated with BRB fault. The related experiment on a 3-kW, 380-V, 50-Hz induction motor has been conducted, and results show the superiority of the new criterion over Filippetti criterion.

Induction motor fault detection using vibration and stator current methods

Induction motors are widely used in industry as prime electromechanical energy conversion devices. Consequently, the condition monitoring and fault diagnosis of induction motors have received significant attention recently and become an integrated part of various maintenance strategies (for example preventive, condition-based and reliability-based maintenance). This paper presents a comparison of results of induction motor broken rotor bar fault detection using vibration and stator current methods. A broken rotor bar fault was induced into in a variable speed three-phase induction motor. Both the vibration and stator current signatures were acquired under different speed and load conditions. The fault detection sensitivities of vibration and stator current methods are evaluated. This paper also addresses the relationship between current and vibration signatures under normal and faulty motor conditions using correlation and frequency response methods. This relationship is desirable in order to determine the fault signature transmission mechanism and to exclude the irrelevant vibration sources so as to enhance fault detection accuracy. The relationship, studied during steady-state operation and start-up, enabled the identification of the vibrations from other sources.

A novel detection method of motor broken rotor bars based on wavelet ridge

Detection of cage motor broken rotor bars has long been an important but difficult job in the detection area of motor faults. The characteristic frequency component of faulted rotor (CFCFR) is very close to the power frequency component but by far less in amplitude, which brings about great difficulty for accurate detection. A new detection method based on wavelet ridge is presented in this paper. Aiming at the motor's starting period during which the motor accelerates progressively and CFCFR approaches the power frequency gradually in frequency spectrum, the wavelet ridge-based method is adopted to analyze this transient procedure and the CFCFR is extracted. The influence of power frequency can be effectively eliminated, and detection accuracy can be greatly improved by using the approach presented in this paper. Also, this is indeed a novel but excellent approach for the detection domain of cage induction motor broken rotor bars.

Science, technology and innovation

Induction motors are important part of safe and efficient running of any industrial plant. These motors are often used in industrial applications thanks to their usability and their robustness. Faults and failures of induction machine can lead to excessive downtimes processes; generate large losses in revenues and long term maintenance. Early detection of motor abnormalities would help avoiding costly breakdowns. In this paper a diagnostic technique of induction motor broken rotor bars is presented. The applied method is the so-called Motor Current Signature Analysis (MCSA) which utilized the results of spectral analysis of the stator current. The broken rotor bars and rings will cause twice slip frequency side bands around the supplying frequency. The fault detection method consists in monitoring of stator phase current spectrum. Twice slip frequency side bands around the main frequency detected by spectral analysis is an indicator of the broken bars. The experimental results show the efficiency of the method.