Induction motor inter turn fault detection using infrared thermographic analysis

Induction motors are the most commonly used prime movers in industries. These are subjected to various environmental, thermal and load stresses that ultimately reduces the motor efficiency and later leads to failure. Inter turn fault is the second most commonly observed faults in the motors and is considered the most severe. It can lead to the failure of complete phase and can even cause accidents, if left undetected or untreated. This paper proposes an online and non invasive technique that uses infrared thermography, in order to detect the presence of inter turn fault in induction motor drive. Two methods have been proposed that detect the fault and estimate its severity. One method uses transient thermal monitoring during the start of motor and other applies pseudo coloring technique on infrared image of the motor, after it reaches a thermal steady state. The designed template for pseudo-coloring is in acquiescence with the InterNational Electrical Testing Association (NETA) thermographic standard. An index is proposed to assess the severity of the fault present in the motor.     

Infrared thermography based diagnosis of inter-turn fault and cooling system failure in three phase induction motor

Thermography has been widely used as a technique for anomaly detection in induction motors. International Electrical Testing Association (NETA) proposed guidelines for thermographic inspection of electrical systems and rotating equipment. These guidelines help in anomaly detection and estimating its severity. However, it focus only on location of hotspot rather than diagnosing the fault. This paper addresses two such faults i.e. inter-turn fault and failure of cooling system, where both results in increase of stator temperature. Present paper proposes two thermal profile indicators using thermal analysis of IRT images. These indicators are in compliance with NETA standard. These indicators help in correctly diagnosing inter-turn fault and failure of cooling system. The work has been experimentally validated for healthy and with seeded faults scenarios of induction motors.     

基于灰色关联和D-S证据理论的感应电转子故障诊断

针对单一的灰色关联或D-S证据理论在转子故障诊断中存在的不足,将灰色关联和D-S证据理论相融合的决策级信息融合方法应用到感应电机转子故障诊断中;首先用灰色关联对故障进行初步诊断,然后,将灰色关联分析的诊断输出结果作为D-S证据理论的基本概率分配,最后,依据证据组合规则进行合成,得出转子故障的最终诊断结果;实验仿真结果验证了方法在转子故障诊断中的有效性,可以减小诊断的不确定性,提高故障的诊断准确率和诊断精度。     

Time-resolved infrared radiometry with step heating. A review

In contrast to most infrared radiometry techniques used for nondestructive evaluation which follow the sample cooling after pulsed heating, the technique termed time-resolved infrared radiometry with step heating (TRIR) follows the surface temperature rise as a function of time during the heating pulse. This approach allows identification of subsurface features and determination of thermal properties with the same speed as other thermal techniques, but keeps the required heating power and resulting surface temperature small. This permits the use of heat sources such as microwaves and RF induction heating where high peak power is often not available. One of the most attractive features of the TRIR method is the ability to calibrate the temperature response early, when the sample is thermally-thick. This allows correction for inhomogeneous heat source distributions and differentiation between backing materials. A fast algorithm has been developed to calculate thermal transit times and therefore generate quantitative depth images of subsurface features. This paper will describe the TRIR approach and the analysis of its time response, including the calibration at early times. Examples will be described for laser heating on zirconia coatings, corroded aluminum, and graphite composites, and the use of microwaves and RF induction heating as heating sources.     

Performance characteristics of Brownian motors

Brownian motors are nonequilibrium systems that rectify thermal fluctuations to achieve directed motion, using spatial or temporal asymmetry. We provide a tutorial introduction to this basic concept using the well-known example of a flashing ratchet, discussing the micro- to nanoscopic scale on which such motors can operate. Because of the crucial role of thermal noise, the characterization of the performance of Brownian motors must include their fluctuations, and we review suitable performance measures for motor coherency and efficiency. Specifically, we highlight that it is possible to determine the energy efficiency of Brownian motors by measuring their velocity fluctuations, without detailed knowledge of the motor function and its energy input. Finally, we exemplify these concepts using a model for an artificial single-molecule motor with internal degrees of freedom.     

Measurements of power loss distribution in a typical stator core under PWM voltage excitation

The pulse width modulated (PWM) inverter is widely used to feed small induction motors for variable speed and torque control. When a laminated stator core is energised in this way additional iron losses occur due to localised distorted flux. Flux density and power loss distribution under PWM and sinusoidal voltage excitations were measured in a typical induction motor stator core lamination at 1.3 T, 50 Hz by using a computer-aided magnetising system to set up flux distribution as would occur in a practical three-phase stator core. The iron loss increased 15–20% under PWM excitation. The loss increase under PWM excitation in the stator core laminations was 3% lower than in Epstein strips of the same electrical steel under the same conditions showing an effect of the magnetic circuit geometry.     

Motor proteins transporting cargos

Processive motor proteins such as kinesin and myosin-V are enzymes that use the energy of ATP hydrolysis to travel along polar cytoskeletal filaments. One of the functions of these proteins is the transport of vesicles and protein complexes that are linked to the light chains of the motors. Modeling the light chain by a linear elastic spring, and using the two-state model for one- and two-headed molecular motors, we study the influence of thermal fluctuations of the cargo on the motion of the motor-cargo complex. We solve numerically the Fokker-Planck equations of motor motion, and find that the mean velocity of the motor-cargo complex decreases monotonously as the spring becomes softer. This effect is due to the random force of thermal fluctuations of the cargo disrupting the operation of the motor. Increasing the size (thus, the friction coefficient) of the cargo also decreases the velocity. Surprisingly, we find that for a given size of the cargo, the velocity has a maximum for a certain friction of the motor. We explain this effect by the interplay between the characteristic length of thermal fluctuations of the cargo on a spring, the motor diffusion length, and the filament period. Our results may be relevant for the interpretation of single-molecule experiments with molecular motors (bead assays), where the motor motion is observed by tracking of a bead attached to the motor.     

Energy transformation in biological molecular motors

Biological molecular motors transform the metabolic free energy into the directed movement. The physical principles governing this transformation are very different from the principles underlying the manmade macroscopic motors. Theoretical analysis shows that the internal thermal diffusion in motor proteins is a key element of the process, and the chemical energy performs no mechanical work directly but instead it is used for rectifying the diffusion. A few specific motor systems are considered to illustrate the general principle. The principle of rectified thermal diffusion has recently received a great support from the single-molecule studies.     

Characterization and sensor applications of polycarbonate optical fibers

Some of the optical, mechanical, thermal, and chemical tests performed on a polycarbonate optical fiber (Optipol) developed by BAYER AG are described in this paper. Allthe tests were mainly done in order to evaluate the performances of this optical fiber, looking for its application as light transmitter in Local Area Networks (LANs) and sensors manufacture in the automobile industry. Some sensors using this fiber are also described in this paper: one speedometer, one tachometer, and one magnetometer. The last two sensors are Faraday effect sensors and have been developed with polycrystalline Cd_1-xMn_x, Te. This low-cost Faraday rotator has been specially manufactured by the authors to be used in industrial applications.     

三相异步电动机一相绕组短路后另二相绕组组合运行分析

当三相异步电动机正常运行时因某种原因一相绕组烧毁,通过对剩下二相绕组重新组合的3 种方法进行分析,发现其中二相零接法在适当降低负载功率情况下,电机可连续运行.     

A composite micromotor driven by self-thermophoresis and Brownian rectification

Brownian motors and self-phoretic microswimmers are two typical micromotors, for which thermal fluctuations play different roles. Brownian motors utilize thermal noise to acquire unidirectional motion, while thermal fluctuations randomize the self-propulsion of self-phoretic microswimmers. Here we perform mesoscale simulations to study a composite micromotor composed of a self-thermophoretic Janus particle under a time-modulated external ratchet potential. The composite motor exhibits a unidirectional transport, whose direction can be reversed by tuning the modulation frequency of the external potential. The maximum transport capability is close to the superposition of the drift speed of the pure Brownian motor and the self-propelling speed of the pure self-thermophoretic particle. Moreover, the hydrodynamic effect influences the orientation of the Janus particle in the ratched potential, hence also the performance of the composite motor. Our work thus provides an enlightening attempt to actively exploit inevitable thermal fluctuations in the implementation of the self-phoretic microswimmers.     

Transport by Molecular Motors in the Presence of Static Defects

The transport by molecular motors along cytoskeletal filaments is studied theoretically in the presence of static defects. The movements of single motors are described as biased random walks along the filament as well as binding to and unbinding from the filament. Three basic types of defects are distinguished, which differ from normal filament sites only in one of the motors’ transition probabilities. Both stepping defects with a reduced probability for forward steps and unbinding defects with an increased probability for motor unbinding strongly reduce the velocities and the run lengths of the motors with increasing defect density. For transport by single motors, binding defects with a reduced probability for motor binding have a relatively small effect on the transport properties. For cargo transport by motors teams, binding defects also change the effective unbinding rate of the cargo particles and are expected to have a stronger effect.     

Introduction to the physics of Brownian motors

A detailed introduction to directed transport in Brownian motors occurring in spatially periodic systems far from equilibrium is presented. We elucidate the prominent physical concepts and novel phenomena with a representative dissipative Brownian motor dynamics. Its main ingredient is a thermal noise with time-dependent temperature modulations that drive the system out of thermal equilibrium in a spatially asymmetric (ratchet-) potential. Yet, this asymmetric setup does not exhibit a concomitant obvious bias into one or the other direction of motion. Symmetry conditions for the appearance (or not) of directed current, its reversal upon variation of certain parameters, and various other generic features and applications are discussed. In addition, we provide a systematic classification scheme for Brownian motor models and review historical landmark contributions to the field. Received: 9 November 2001 / Accepted: 14 January 2002 / Published online: 22 April 2002     

分子马达与布朗马达

综述了有关分子马达,主要是肌球蛋白马达和动蛋白马达的实验研究进展情况,并对理论模型,特别是近年来广为流行的布朗马达模型作了介绍和评论。最后展望了这一领域的发展前景及其所面临的挑战性问题。     

A general two-cycle network model of molecular motors

Molecular motors are single macromolecules that generate forces at the piconewton range and nanometer scale. They convert chemical energy into mechanical work by moving along filamentous structures. In this paper, we study the velocity of two-head molecular motors in the framework of a mechanochemical network theory. The network model, a generalization of the recently work of Liepelt and Lipowsky [Steffen Liepelt, Reinhard Lipowsky, Kinesins network of chemomechanical motor cycles, Physical Review Letters 98 (25) (2007) 258102], is based on the discrete mechanochemical states of a molecular motor with multiple cycles. By generalizing the mathematical method developed by Fisher and Kolomeisky for a single cycle motor [Michael E. Fisher, Anatoly B. Kolomeisky, Simple mechanochemistry describes the dynamics of kinesin molecules, Proceedings of the National Academy of Sciences 98 (14) (2001) 7748-7753], we are able to obtain an explicit formula for the velocity of a molecular motor.     

Fusion Domain-Adaptation CNN Driven by Images and Vibration Signals for Fault Diagnosis of Gearbox Cross-Working Conditions

The vibration signal of gearboxes contains abundant fault information, which can be used for condition monitoring. However, vibration signal is ineffective for some non-structural failures. In order to resolve this dilemma, infrared thermal images are introduced to combine with vibration signals via fusion domain-adaptation convolutional neural network (FDACNN), which can diagnose both structural and non-structural failures under various working conditions. First, the measured raw signals are converted into frequency and squared envelope spectrum to characterize the health states of the gearbox. Second, the sequences of the frequency and squared envelope spectrum are arranged into two-dimensional format, which are combined with infrared thermal images to form fusion data. Finally, the adversarial network is introduced to realize the state recognition of structural and non-structural faults in the unlabeled target domain. An experiment of gearbox test rigs was used for effectiveness validation by measuring both vibration and infrared thermal images. The results suggest that the proposed FDACNN method performs best in cross-domain fault diagnosis of gearboxes via multi-source heterogeneous data compared with the other four methods.     

Experimental studies of the myosin-actin motor

The mechanical processes generated by the molecular motors, myosin and actin, were measured using single molecule imaging, manipulation, and nanometry techniques. It was shown that the mechanical events of myosin are not tightly coupled with the ATP hydrolysis reaction and that myosin molecules move stochastically. These results indicate that the movement of myosin is driven by thermal motion rather than structural changes occurring in the myosin molecules. Thermal Brownian motion must be biased using the energy released from the hydrolysis of ATP. Thus, the molecular motors can harness thermal energy to perform mechanical work efficiently. Received: 20 November 2001 / Accepted: 11 February 2002 / Published online: 22 April 2002     

几种直方图变换法在输电接头红外热像增强中的对比研究

由红外热像仪直接得到的热像会受很多外来因素的干扰而致使图像模糊不清、对比度差,由此在故障诊断过程中,需要对热像进行后续增强处理。总结了影响热故障红外检测准确性的外部因素,分析了输电接头热像的基本特征,采用了基于平方根灰度变换直方图修正和全局均衡化两种方法对热像进行了增强处理。在分析上述两种方法优劣的基础上,提出了一种基于线性平滑滤波的局部均衡化方法。结果表明,基于线性平滑滤波的局部均衡化方法对于处理输电接头热像更有效。