Eccentricity, Vibration, and Shaft Currents in Turbine Generators [includes discussion]

Rosenberg, L. T.

doi:10.1109/aieepas.1955.4499047

Cited by 15 publications

(9 citation statements)

References 8 publications

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“…So misaligned/unbalanced rotors account for about 50% of all fault conditions at the origin of industrial down-times. Shaft unbalances/misalignments can produce a stator-rotor rub resulting in damages to stator and rotor windings and cores in the worst case [1]- [3], but more frequently they lead to bearing overheating and abnormal wear due to the unbalanced magnetic pull (UMP) [4], or even to bearing fault due to vibrations and shaft currents [5]. In 2005 the Italian Navy carried out a report of failures specifically related to mechanical problems of onboard-ship generators, and the actual check and maintenance procedures underwent a critical revision.…”

Section: Introductionmentioning

confidence: 99%

DIEM project's outcomes: An automated air-gap monitoring approach for Italian Navy's on-board low-voltage generators

Bruzzese

Mazzuca

2012

2012 Electrical Systems for Aircraft, Railway and Ship Propulsion

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The Italian Navy committed in 2006 to the Department of Astronautics, Electrical, and Energy Engineering-University of Rome "Sapienza" a Research Program aimed to define an automated procedure for air-gap monitoring of onboard generators. An effective solution was needed to overcome the heavy shortcomings of usual manual measurement practices. This paper describes the research work which led to very reliable rotor eccentricity indicators, based on measurement of internal currents in armature windings with parallel connections. The new approach permits absolute on-line estimations of both static and dynamic rotor shaft misalignments. A fully operative demonstrative system has been developed in the Department's laboratory. A four pole 17kV A generator was used for experiments, with artificial eccentricities produced by an apposite mechanical flange. A virtual instrument was used for data acquisition and processing, so obtaining a real-time estimation of the actual shaft misalignment. Comparison of data obtained from simulations and tests prove the reliability of the proposed methodology.

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Section: Introductionmentioning

confidence: 99%

DIEM project's outcomes: An automated air-gap monitoring approach for Italian Navy's on-board low-voltage generators

Bruzzese

Mazzuca

2012

2012 Electrical Systems for Aircraft, Railway and Ship Propulsion

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“…Due to the assembly quality, the bearing damage, and the performing environments, most generators are running under an air-gap eccentricity condition [1]. The air-gap eccentricity, which is also usually named as rotor eccentricity by many scholars, appears as the air-gap is larger on one side but meanwhile smaller on the other side.…”

Section: Introductionmentioning

confidence: 99%

Impact of Different Static Air-Gap Eccentricity Forms on Rotor UMP of Turbogenerator

Deng

Tang

et al. 2016

Mathematical Problems in Engineering

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Theoretical analysis and numerical FEM calculations, together with segmental experiment studies, are used to study the impact of the static air-gap eccentricity forms on the rotor unbalanced magnetic pull (UMP) of turbogenerator. The universal expression of the magnetic flux density under different forms of SAGE is firstly deduced, based on which the detailed UMP formulas for the normal condition and three SAGE cases are obtained, respectively. Then the exciting characteristics of the UMP for each SAGE form to generate vibrations are analyzed. Finally, numerical FEM calculations and segmental experiments are carried out to investigate the effect of SAGE forms on the rotor UMP, taking the SDF-9 type non-salient-pole fault simulating generator as the object. It is shown that, no matter what kind of SAGE occurs, amplitude increments at each even harmonic component of the UMP and the rotor vibration, especially the 2nd harmonic component, will be brought in. Meanwhile, the UMP keeps directing to the very position where the minimum radial air-gap is. Among the different SAGE forms, the rotor offset has the most sensitive effect on the rotor UMP and vibration, while the stator ellipse deformation has the weakest impact.

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“…Researchers have given this kind of asymmetry a professional definition as air-gap eccentricity or rotor eccentricity [1][2]. Air-gap eccentricity widely exists in almost every generator and motor, and can be classified as three types [3][4][5], i.e., the static air-gap eccentricity (SAGE) whose minimum air-gap position is stable (such as the offset of the rotor), the dynamic airgap eccentricity whose minimum air-gap position will be changed as the rotor rotates (for example, the rotor is bending, or the rotor section is an ellipse), and the mixed air-gap eccentricity which is composed of the former two.…”

Section: Introductionmentioning

confidence: 99%

United Electromagnetic Characteristics and Online Monitoring Method of Static Air-gap Eccentricity of Turbo-Generator

Tang¹,

Ke²,

He³

et al. 2016

Journal of Electrical Engineering and Technology

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-The purpose of this paper is to investigate the united Electromagnetic characteristics for the effective monitoring on the static air-gap eccentricity (SAGE) of turbo-generator. Different from other studies, this paper not only studies on the unbalanced magnetic pull (UMP) and the vibration characteristics of the stator and the rotor, but also investigates the harmonic features of the magnetic flux density and the circulating current inside the parallel branches (CCPB). The theoretical calculation, together with the finite-element-method (FEM) simulation and the experiment verification, is taken for a SDF-9 type non-salient generator. It is shown that, when SAGE occurs, apparent doublefrequency UMP and vibrations will be produced both on the stator and the rotor, while the CCPB will have an obvious increment at the 1 st harmonic component. In addition, the amplitude of the magnetic flux density will be of cosine distribution in the circumferential position of the air-gap, while in normal condition it is a constant. Moreover, the pass-band amplitude, together with the 1 st harmonic of the magnetic flux density, will be enlarged as well. These united electromagnetic characteristics can be used as the diagnosis and monitoring criterion for SAGE.

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Eccentricity, Vibration, and Shaft Currents in Turbine Generators [includes discussion]

Cited by 15 publications

References 8 publications

DIEM project's outcomes: An automated air-gap monitoring approach for Italian Navy's on-board low-voltage generators

DIEM project's outcomes: An automated air-gap monitoring approach for Italian Navy's on-board low-voltage generators

Impact of Different Static Air-Gap Eccentricity Forms on Rotor UMP of Turbogenerator

United Electromagnetic Characteristics and Online Monitoring Method of Static Air-gap Eccentricity of Turbo-Generator

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