• Title/Summary/Keyword: Rotor Unbalance

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A New Hybrid "Park's Vector - Time Synchronous Averaging" Approach to the Induction Motor-fault Monitoring and Diagnosis

  • Ngote, Nabil;Guedira, Said;Cherkaoui, Mohamed;Ouassaid, Mohammed
    • Journal of Electrical Engineering and Technology
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    • v.9 no.2
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    • pp.559-568
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    • 2014
  • Induction motors are critical components in industrial processes since their failure usually lead to an unexpected interruption at the industrial plant. The studies of induction motor behavior during abnormal conditions and the possibility to diagnose different types of faults have been a challenging topic for many electrical machine researchers. In this regard, an efficient and new method to detect the induction motor-fault may be the application of the Time Synchronous Averaging (TSA) to the stator current Park's Vector. The aim of this paper is to present a methodology by which defects in a three-phase wound rotor induction motor can be diagnosed. By exploiting the cyclostationarity characteristics of electrical signals, the TSA method is applied to the stator current Park's Vector, allowing the monitoring of the induction motor operation. Simulation and experimental results are presented in order to show the effectiveness of the proposed method. The obtained results are largely satisfactory, indicating a promising industrial application of the hybrid Park's Vector-TSA approach.

The Optimization Design of Rotor Slot Shape in Outer-Rotor Type Induction Motor Reducing Unbalance Force (외전형 유도전동기의 불균형력 저감을 위한 회전자 슬롯형상 최적화)

  • Kim, Kyung-Su;Cha, Hyun-Rok;Yun, Cheol-Ho;Jung, Tae-Uk;Park, Seong-Jun
    • Proceedings of the KIEE Conference
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    • 2007.07a
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    • pp.864-865
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    • 2007
  • 외전형 유도전동기는 내전형에 비해 회전자가 외부에 존재하는 특징을 가지고 있어서 제품의 소형화 및 경량화를 시킬 수 있다는 장점이 있다. 하지만 외전형은 회전자의 직경이 내전형에 비하여 크기 때문에 조립 공정상에 존재하게 되는 회전자와 고정자간의 이심률에 따른 제품 전체의 불균형력이 상대적으로 크며, 이로 인해 모터의 정속적인 운전 방해 및 불규칙한 출력토크로 인한 제품 작동상의 오류발생이 더 크게 나타난다. 본 논문에서는 외전형 유도전동기에서 존재하는 이심률의 크기에 따른 불균형력이 최소화 될 수 있는 슬롯형태를 찾기 위해 회전자 슬롯의 형태를 전폐형, 반폐형, 개구형태의 3가지형태로 변경시킨 후, 이를 전자장 해석을 통해 불균형력을 비교하였다. 또한 이심률이 증가함에 따라 나타나는 불균형력의 증대를 슬롯 형태에 따라 비교 분석하여, 불균형력에 최적화된 외전형 모터의 슬롯형태를 알아보았다.

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Experimental Study on Noise Reduction of Fan for Automotive Air Conditioner (차량용 공조 팬의 소음 저감에 대한 실험적 연구)

  • Lee, Jin-Kab;Chung, Byung-Hoon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.1
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    • pp.51-56
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    • 2013
  • This paper is the experimental study to investigate the noise sources location in order to reduce the noise level of line flow fan for the air conditioner in the subway car. The noise of line flow fan is caused by various factors such as the turbulence by air flow, random noise, noise of blade passing frequence(681Hz) and noise due to structural vibration of rotor unbalance(28.4Hz) by motor revolution. By performing the noise reduction on each sound source, the noise level is decreased as much as 5.7dB(A) through the controls of housing guide angle and distance, the configuration changes of flow passage shape and rotor balancing.

Investigation of Dynamic Property of Squeeze Film Damper Using Magnetic Fluid (자성유체를 이용한 스퀴즈 필름 댐퍼의 동특성 분석)

  • Ha, Jong-Yong;Kim, Yong-Han;Yang, Bo-Suk;Morishita Shin;Ahn, Kyoung-Kwan;Ahn, Young-Kong
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.11 s.104
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    • pp.1262-1267
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    • 2005
  • The paper presents the identification of dynamic property of a rotor system with a squeeze film damper (SFD) using magnetic fluid. An electromagnet Is installed in the inner damper of the SFD. The magnetic fluid is well known as a functional fluid. Its rheological property can be changed by controlling the applied current to the fluid and the fluid can be used as lubricant. Basically, the proposed SFD has the characteristics of a conventional SFD without an applied current, while the damping and stiffness Properties change according to the variation of the applied electric current. Therefore, when the applied current is changed, the whirling vibration of the rotor system can be effectively reduced. The clustering-based hybrid evolutionary algorithm (CHEA) is used to identify linear stiffness and damping coefficients of the SFD based on measured unbalance responses.

A Case Study on the Reduction of Noise and Vibration at the Backpass Heat Surface in the Power Plant Boiler (300MW급 증기터빈의 베어링 윤활유 온도조정에 의한 오일휩 제거방법에 관한 연구)

  • Hwang, Dal-Yeon;Moon, Seung-Jae;Lee, Jae-Heon
    • Plant Journal
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    • v.4 no.4
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    • pp.56-61
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    • 2008
  • The phenomena of oil whip in steam turbines take place for the unbalance force between a rotor shaft and bearing oil film. The several parameters that affect onset of oil whip have been well known. However, the major parameter of oil whip is shaft mis-alinement. A oil whip causes the high vibration and the shutdown of rotor system. We mostly stop the steam turbine to adjust a shaft re-alinement concerning oil whip. In this case, it needs many costs for maintenance and long shutdown times. In this study, we study and observe the oil whip of the 300MW steam turbine in many years and we conduct the field test for another steam turbine for reducing vibration from oil whip. The results of this study are that a oil whip takes place with a particular rotating speed or a particular turbine output and the oil temperature change is a very effective method for on-line oil whip treatment.

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A Study on the Turbopump Rotordynamic Characteristics due to Bearing Housing Structural Flexibility (베어링 하우징의 구조 유연성에 따른 터보펌프 회전체동역학 특성 연구)

  • Jeon, Seong Min;Yoon, Suk-Hwan;Kim, Jinhan
    • Journal of the Korean Society of Propulsion Engineers
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    • v.18 no.2
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    • pp.35-41
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    • 2014
  • A rotordynamic analysis is performed for a turbopump of 7 ton class liquid rocket engine considering bearing housing structural flexibility. Stiffness and damping characteristics of ball bearings and pump noncontact seals are reflected in a rotordynamic model. A dynamic model of bearing housing with lumped mass and stiffness is also applied to the rotordynamic analysis. Rotor critical speed and onset speed of instability are predicted from synchronous rotor mass unbalance response and complex eigenvalue analyses. The bearing housing structural flexibility effect on rotordynamic characteristics is investigated for both of bearing loaded and unloaded conditions respectively. From the numerical analysis, it is found that the effect of the housing structural flexibility significantly reduces the rotor critical speed and onset speed of instability.

Condition Monitoring and Fault Diagnosis System of Rotating Machinery (회전기기의 상태감시 및 결함탐지 시스템)

  • Jeong, Sung-Hak;Lee, Young-Dong
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2016.10a
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    • pp.819-820
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    • 2016
  • Electrical power distribution is consists of high voltage, low voltage and motor control center(MCC). Motor control centers involves turning the motor on and off, it is configured electronic over current relay to detect a motor overcurrent flows. Existing electronic over current relay detects electrical fault such as overcurrent, undercurrent, phase sequence, negative sequence current, current unbalance and earth fault. However, it is difficult to detect mechanical fault such as locked rotor, motor stator and rotor and bearing fault. In this paper, we propose a condition monitoring and fault diagnosis system for electrical and mechanical fault detection of rotating machinery. The proposed system is designed with signal input and control part, system interface part and data acquisition board for condition monitoring and fault diagnosis, it was possible to detect electrical fault and mechanical fault through measurement and control of insulation resistance, locked rotor, MC counter and bearing temperature.

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Development of Fault-Simulated System for Induction Motors (유도전동기 고장모의 시뮬레이터 개발)

  • Hwang, Don-Ha;Lee, Ki-Chang;Kang, Dong-Sik;Kim, Byong-Kuk;Jo, Won-Young;Cho, Yun-Hyun
    • Proceedings of the KIEE Conference
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    • 2006.04b
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    • pp.182-184
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    • 2006
  • A down-scaled simulator is developed to simulate typical faults in induction motor such as short-turn stator winding, broken rotor bar, dynamic and static air-gap eccentricity, bearing trouble, and mechanical unbalance. The simulator is used as an initial builder to develop design algorithm for real-time faults detecting system by processing an abnormal signal and characteristics in each fault.

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Optimum Field Balancing of Ratating Machinery Using Genetic Algorithm (유전 알고리즘을 이용한 회전기계의 최적 현장평형잡이)

  • Choi, Won-Ho;Yang, Bo-Suk;Joo, Ho-Jin
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.6
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    • pp.1819-1826
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    • 1996
  • This paper present the claculating method of optimum correction mass within permissible vibration linits for ratating machinery in two-plane field balancing. Basic technique of this method is based on influence coefficient method, and grphic vector composition that the resultant of two influence vectors obtained by trial mass have to be equilibrium with initial vibration vector in the each correction plane. Genetic algorithm which is a search algorithm based on the mechanism of natural selection and natural genetics is sued for vector composition, and SUMT method is used to objective function which seeks optimum correction mass for balancing a rotor.

Effect of Seal Wear on the Rotordynamics of a Multistage Turbine Pump (시일의 마멸이 다단 터빈 펌프 동특성에 미치는 영향)

  • 김영철;이동환;이봉주
    • Journal of KSNVE
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    • v.7 no.6
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    • pp.1015-1023
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    • 1997
  • Rotordynamic analysis of a multistage turbine pump using finite element method is performed to investigate the effects of seal wear on its system behavior. Stiffness and damping coefficents of the 2-axial grooved bearing are obtained as functions of rotating speed. Stiffness and damping coefficients of plane annuler seals are calculated as functions of rotating speed as well as seal clearance of seals become larger, these stiffness and damping coefficients decrease drastically so that there can be significant changes in whirl natural frequencies and damping characteristics of the pump rotor system. Although a pump is designed to operate with a sufficient seperation margin from the 1st critical speed, seal wear due to long operation may cause a sudden increase in vibration amplitude by resonance shift and reduce seal damping capability.

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