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Advanced analysis of the motor starting currents enables very reliable diagnostics of the rotor condition, providing immunity against the eventual false alarms obtained with the conventional MCSA. However, the application of this methodology has been mainly restricted to the case of line-started machines. Its extension to the cases of soft-started or inverted-fed motors has been barely investigated,...
Unbalance forces are a crucial issue in rotor systems. Often it is of interest to monitor the states of unbalances while the rotor is running in order to prevent damages to the rotor system. For the model based unbalance monitoring a rotor model is required to represent the behavior of the rotor system and the influences of the unbalances. The feasibilities of the methods are often limited by the...
Orbit identification plays an important role for rotor system fault diagnosis. Due to signals noise and the nonlinear working condition of the rotor system, the orbit information which indicates the fault is very difficult to have got. A new method based on isometric feature mapping (ISOMAP) of orbit identification is provided in this paper. Firstly, the vibration signal of each orbit in a two-dimensional...
In the paper, we analyze and study the status character in detail which a rotor of some rotating mechanism exist in some different fault types and different fault strengths. The research result shows that a fault rotor reveals distinct return map images, which the rotor runs in different malfunction status or different malfunction strengths. The research gives an effective method to explore fault...
Abstract-Based on the fact that the fractal scaleless band and correlation dimension will gradually reach saturation and consensus along with the increase of the embedding dimension, an improved correlation dimension algorithm is proposed. The proposed algorithm, which is composed of complex auto-correlation method and curve-line-curve fitting method, can automate the calculation of reconstructing...
Condition monitoring in industry is desirable for increasing machinery availability, reducing consequential damage, and improving operational efficiency. This is significant in industries employing heavy duty machines. Here, an attempt is made to demonstrate the various faults that occur in induction motors, and also to give an insight about the techniques that are used for corrective/preventive action...
This paper presents an improved technique for detection of mass unbalance in rotor of an induction motor by the analysis of transient stator current during starting period using both discrete wavelet transform (DWT) and continuous wavelet transform(CWT). The unbalanced magnetic pull due to centrifugal force developed for mass unbalance in rotor produces excessive vibration in the rotor as well as...
This paper is a continuation of a previous work regarding the induction motors diagnosis problem. An on-line fault detection strategy has been proposed using a graphical signature generation tool. In this work, the graphical tool is used for an off-line diagnosis including isolation and estimation. The underlying diagnosis problem corresponds to variations affecting three of system's parameters, namely,...
This paper introduces a new diagnosis technique for the detection of incipient electrical rotor faults in doubly fed induction Machine (DFIM) for wind power systems. In the considered application, the rotor is supplied by a static converter for the control of active and reactive power flows from the generator to the electrical grid. A new diagnostic method based on the rotor modulating signals pre-processing...
Online monitoring of rotary machines, like induction motors, can effectively diagnosis electrical and mechanical faults. The origin of most recurrent faults in rotary machines is in the components: bearings, stator, rotor and others. Different methodologies based on current and vibration monitoring have been proposed using FFT and wavelet analysis for preventive monitoring of induction motors resulting...
In order to accurately make out early fault diagnosis of rotor system with weak signal, a novel fault diagnosis method based on empirical mode decomposition(EMD) associated with chaos oscillator was presented. Weak periodic signals can be detected by identifying the transformation of the chaotic oscillator from the chaotic state to the large-scale periodic state when a weak external periodic signal...
This paper discusses a problem of modeling induction machines when some faults appear in a cage by using a model reduced to four equations. Starting from an advance mathematical model with full representation of a cage and considering arbitrary cage faults the steady-state equations are developed. Those equations are reduced to four equations using symmetrical components of stator and rotor quantities...
The state-of-the-art advancement in wind turbine condition monitoring and fault diagnosis for the recent several years is reviewed. Since the existing surveys on wind turbine condition monitoring cover the literatures up to 2006, this review aims to report the most recent advances in the past three years, with primary focus on gearbox and bearing, rotor and blades, generator and power electronics,...
Among the methods of fault diagnosis based on the current analysis for squirrel cage induction motors (SCIM), the faultspsila characteristic components are often submerged by fundamental component and noises, especially for the broken rotor bars, and how to effectively eliminate the influences of the fundamental component and noises is essential for the diagnosis system. Fault diagnosis way based...
When motor faults (rotor broken-bar, stator turn- to-turn short, etc.) occur in a motor, its internal current distribution and electromagnetic field will change, which will further cause some variations to stator and rotor parameters. In this paper, the method conjoint of Finite Element Method and Energy Perturbation Method is used to calculate the motor's inductance parameter, and finite-element...
A bilinear observer is presented to detect current sensor faults in a doubly fed induction generator. The state space model is derived from the voltage equations of stator and rotor. The bilinear behaviour of induction machines and its influence on the state space model is discussed. An open loop model suffers from model and parameter uncertainty. A closed loop observer is shown to greatly reduce...
The double fault in squirrel cage induction motors, which means that rotor bar breaking fault and stator winding inter-turn short circuit fault are present simultaneously, has been investigated based on the motor multi-loop model. The results indicate that the features of rotor bar breaking fault and stator winding inter-turn short circuit fault always interlace and interact to some extent. The detection...
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