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This research deals with the comparison of fault signatures in induction motors. The primary objective is to study and analyze the similarities in the electrical and mechanical fault signatures, and to determine the suitability of the former for effective motor fault detection. Currently, vibration analysis is the dominant means for mechanical fault detection for use in condition-based maintenance. The use of electrical signatures for mechanical fault detection in electric motors is becoming of interest. Due to its cost-effective nature and ease of use, electrical sensors are preinstalled at the motor switchgear by manufacturers. However in order to achieve this for mechanical faults, a systematic comparison between the vibration signatures and electric current signatures must be performed to study the effectiveness of such an approach. The behavior of vibration signatures as measured through tri-ax accelerometers installed at both in-board and out-board sides, and the three phase motor current signatures as compared to their corresponding healthy baselines is analyzed through a sequence of signal processing algorithms. The procedure is carried out for different types of mechanical faults including broken rotor bars, air-gap eccentricity, mechanical imbalance and deteriorating bearings staged on motors of different make and power rating. A comparison is then made between the two fault indicators derived from mechanical and electrical measurements, respectively.

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Linear induction machines currently play a relatively minor role in the industrial world. This is partly due to relatively high production costs, complexity of construction and the Inability to apply standard mass production techniques. The aim of this thesis is to investigate the design of linear machines that are cheaper and faster to produce, and that may easily be mass-produced This thesis principally concerns the use of concentrated winding linear stators. These are cheap and easy to manufacture and can be easily mass-produced. However, high levels of negative harmonics make them unsuitable for use with simple sheet rotors.

Orientador: Ernesto Ruppeert Filho / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-16T04:00:35Z (GMT). No. of bitstreams: 1 Riehl_RudolfRibeiro_D.pdf: 5043112 bytes, checksum: b6091e6e6b5591d8885535a13baae465 (MD5) Previous issue date: 2010 / Resumo: O objetivo deste trabalho é o de apresentar uma nova metodologia para determinação experimental das capacitâncias parasitas do motor de indução trifásico de rotor em gaiola. As capacitâncias parasitas fazem parte do circuito equivalente do motor para estudos de interferência eletromagnética causada no motor de indução em modo comum quando ele for acionado por inversor controlado por modulação por largura de pulsos (MLP). Os procedimentos propostos para o desenvolvimento deste novo método consistem em: a) determinação dos parâmetros do circuito equivalente do motor de indução trifásico, em regime permanente, através de ensaio em laboratório; b) estabelecer configurações de ligações entre o inversor MLP e o motor para medições das grandezas de interesse que são as seguintes: tensões de modo comum e de eixo, correntes de fuga e de eixo, através de circuito de medição desenvolvido para este fim; c) calcular os valores das capacitâncias parasitas entre estator e carcaça do motor; estator e rotor; rotor e carcaça e de rolamento utilizando a expressão matemática da definição de capacitância; d) utilizar o software Pspice para simular o sistema motor de indução trifásico, alimentado por inversor MLP, com os circuitos equivalentes em baixas e altas frequências; e) obter as formas de onda características do fenômeno de modo comum / Abstract: Three-phase induction motors present stray capacitances. The aim of this thesis is to present a new methodology to experimentally determine these capacitances and also evaluates the effects of electromagnetic interference on the motors in common mode. The proposed procedures to the development of this new methodology consists in: a) identification of the motor equivalent electrical circuit parameters through characteristic tests performed in the laboratory; b) to set up configurations between PWM inverter and the motor for voltage and current measurements: common mode and shaft voltages, leakage and shaft (bearing) currents by using a dedicated measuring circuit; c) to calculate the parasitic capacitance values between stator and frame, stator and rotor, rotor and frame and bearings of the motor using the capacitance characteristic equation; d) use the dedicated software Pspice to simulate the system composed by the three-phase induction motor fed by PWM inverter with the equivalent electrical circuit parameters; e) to determine the characteristic waveforms involved in the common mode phenomenon / Doutorado / Energia Eletrica / Doutor em Engenharia Elétrica

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No description available.