Papers by Katalin Agoston
Lecture notes in networks and systems, 2024
Procedia Technology, 2016
Procedia Engineering, 2017
Abstract In this paper we investigate the use and function of vibration and acceleration sensors.... more Abstract In this paper we investigate the use and function of vibration and acceleration sensors. We designed and constructed a data acquisition board using the ADXL202 acceleration sensor, with the possibility of connecting it to a computer, with a real time ...
DOAJ (DOAJ: Directory of Open Access Journals), Dec 1, 2014
This paper presents virtual instruments to simulate the transient state for some simple and compl... more This paper presents virtual instruments to simulate the transient state for some simple and complex circuit. The relative short event between different steady states is the transient state which is followed by energy variation in the circuit. This energy variation produces impulses which propagate through the net and influence other devices. Because there are a lot of equipments operating in switching mode, it is important to study the transient state. To model and study the transient state equations for circuits were written. The article presents the mathematical base of the transient state and types of response of the transient state. The main part is to present the developed virtual instruments for electrical circuits to simulate and to study their transient state. The virtual instruments were developed in LabView. The virtual instruments allow setting different circuit configurations, different values for circuit elements and show the results in analytical and graphical way.
... Using NI data acquisition board the resolution will be 320μV even for an input range of ... o... more ... Using NI data acquisition board the resolution will be 320μV even for an input range of ... of the real signals there were connected different loads: pur resistive, pur inductive, switching power supply, etc. ... The correction factor, the transformation rate for the voltage ku was set to 100. ...
2006 IEEE International Conference on Automation, Quality and Testing, Robotics, 2006
Procedia Manufacturing
This paper presents the importance of motor base vibration measurements; different faults which c... more This paper presents the importance of motor base vibration measurements; different faults which can appear during motor running and how the motor base unbalance and vibration influence the whole system vibration. The electrical and mechanical faults influence the normal functioning of the motor, increase the power consumption, the current, more heat is generated and vibrations are growing too. Balancing is important requirement for motors and all rotating components. An electrical and/or mechanical unbalance affects other parts of the motor or system. A weak motor base is one of the vibration sources which can be detected with vibration transducers. A 3-axis accelerometer was used to detect motor vibration for a small DC motor fixed on different types of base in different manner. A virtual instrument was developed to acquire and analyze the vibration. Analyzing the frequency spectra of the vibration the weak motor base and improper fixing of the motor was highlighted which appear in horizontal direction. Knowing the rotating frequency the measured and analyzed data was compared with the reference data. It is shown that sideband frequencies appear around the fundamental frequency which means an anomaly due to improper motor base.
The 15th International Conference Interdisciplinarity in Engineering
The paper presents the importance of motor vibration study and simulation; different faults which... more The paper presents the importance of motor vibration study and simulation; different faults which can appear during induction motor running and how broken rotor bar influences the whole system vibration. The environmental and internal, electrical and mechanical noises influence the normal functioning of the motor, increase the power consumption, deform the current spectrum, more heat is generated and vibrations are growing. Broken rotor bar changes the magnetic field distribution in the air gap between rotor and stator, unbalanced force appears which cause unwanted vibration and malfunctioning. Electrical equation is written for one rotor loop and the influence of the broken rotor bar is showed. The induction motor vibration can be studied through a simple system model with two degrees of freedom. The system model changes accordingly to the broken rotor bar and this change is studied through the transfer function written for rotor.
Scientific Bulletin of the ''Petru Maior" University of Tîrgu Mureș, 2017
This paper presents the state variables method in the analysis of the transient state. Using this... more This paper presents the state variables method in the analysis of the transient state. Using this method the behaviour of transformers at on/off switching is studied. The transient state is a short event caused by any changes in the system which is followed by an energy modification stored in the system. The energy is stored in capacitors and coils and any modification needs time and has reactions. These reactions can be high impulses of energy which propagate through the network and influence or even destroy other circuit elements or devices. The transient state of an RLC circuit and of a transformer is studied. Differential equations are used and the nonlinearity of the coil is highlighted. Differential equations and the equivalent circuit are used to deduce the state parameter model for the transformer. Equations and equivalent circuit for a real transformer are deduced with and without load at the output. The behaviour of the transformer was studied while functioning in an open ...
Scientific Bulletin of the ''Petru Maior" University of Tîrgu Mureș, 2018
This paper presents the most important nonlinear circuit elements, the equivalent circuits and th... more This paper presents the most important nonlinear circuit elements, the equivalent circuits and the causes of nonlinearity. This is important because the power quality in the power network is strongly influenced by the nonlinear characteristics of the elements and nonlinear functions of different equipments. Some circuits and circuit elements, transformers, induction motors, frequency converters, were studied. The voltage and the current waveform were analysed and the frequency spectra were shown to establish the most considerable harmonics. It is important to study the nonlinear circuits and analyze the harmonic spectra of the distorted current for different inductive load to design the right filter for reducing or eliminating the harmonics. The theoretical background of the distorting state is also presented, what kind of losses appear, and how these losses influence the harmonics. It is shown the reason for what coil and capacitor have nonlinear characteristics and by what is expr...
Acta Marisiensis. Seria Technologica, 2020
This paper presents fault detection techniques, especially the motor current signature analysis (... more This paper presents fault detection techniques, especially the motor current signature analysis (MCSA) which consists of the phase current measurement of the electrical motor’s stator and/or rotor. The motor current signature analysis consists in determining the frequency spectrum (FFT) of the stator current signal and evaluating the relative amplitude of the current harmonics. Sideband frequencies appear in the frequency spectrum of the current, corresponding to each fault. The broken bar is a frequent fault in induction motors with squirrel-cage rotor. It is presented the equivalent circuit for induction motors and the equivalence between the squirrel-cage rotor and the rotor windings. It is also presented an equivalent circuit model for induction motors with squirrel cage rotor, and based on this a Simulink model was developed. It is shown how a broken rotor bar influences the magnetic field around the rotor and through this the stator current. This modification is highlighted th...
Procedia Manufacturing, 2018
Under the concept of "Industry 4.0", production processes will be pushed to be increasingly inter... more Under the concept of "Industry 4.0", production processes will be pushed to be increasingly interconnected, information based on a real time basis and, necessarily, much more efficient. In this context, capacity optimization goes beyond the traditional aim of capacity maximization, contributing also for organization's profitability and value. Indeed, lean management and continuous improvement approaches suggest capacity optimization instead of maximization. The study of capacity optimization and costing models is an important research topic that deserves contributions from both the practical and theoretical perspectives. This paper presents and discusses a mathematical model for capacity management based on different costing models (ABC and TDABC). A generic model has been developed and it was used to analyze idle capacity and to design strategies towards the maximization of organization's value. The trade-off capacity maximization vs operational efficiency is highlighted and it is shown that capacity optimization might hide operational inefficiency.
Procedia Manufacturing, 2019
Under the concept of "Industry 4.0", production processes will be pushed to be increasingly inter... more Under the concept of "Industry 4.0", production processes will be pushed to be increasingly interconnected, information based on a real time basis and, necessarily, much more efficient. In this context, capacity optimization goes beyond the traditional aim of capacity maximization, contributing also for organization's profitability and value. Indeed, lean management and continuous improvement approaches suggest capacity optimization instead of maximization. The study of capacity optimization and costing models is an important research topic that deserves contributions from both the practical and theoretical perspectives. This paper presents and discusses a mathematical model for capacity management based on different costing models (ABC and TDABC). A generic model has been developed and it was used to analyze idle capacity and to design strategies towards the maximization of organization's value. The trade-off capacity maximization vs operational efficiency is highlighted and it is shown that capacity optimization might hide operational inefficiency.
Procedia Technology, 2015
Journal of Electrical and Electronics Engineering, 2014
This paper presents some aspects regarding to small displacement measurement using vibration tran... more This paper presents some aspects regarding to small displacement measurement using vibration transducers. Mechanical faults, usages, slackness's, cause different noises and vibrations with different amplitude and frequency against the normal sound and movement of the equipment. The vibration transducers, accelerometers and microphone are used for noise and/or sound and vibration detection with fault detection purpose. The output signal of the vibration transducers or accelerometers is an acceleration signal and can be converted to either velocity or displacement, depending on the preferred measurement parameter. Displacement characteristics are used to indicate when the machine condition has changed. There are many problems using accelerometers to measure position or displacement. It is important to determine displacement over time. To determinate the movement from acceleration a double integration is needed. A transfer function and Simulink model was determinate for acceleromet...
The sensorless drive of a brushless motor involves the position estimation of the rotor, without ... more The sensorless drive of a brushless motor involves the position estimation of the rotor, without Hall sensors to generate the switching signal. For this reason we need to detect the commutation points. We are studied the currents and phase-to-phase voltages for a small brushless motor. The currents are sensed with current sensors (LEM). A virtual instrument developed in Lab View visualisates the currents and voltages and determinate the commutation points. This is connected to an other VI witch generate the switching signal. In our case the small BLDC is drive in frequency control mode, that means the current impulse has constant Ton/T ratio and variable frequency. The mean value of the current depends on frequency. The developed VIs are able to drive the small BLCD motor.
Procedia Technology, 2014
Mechanical faults, usages, slackness's, cause different noises and vibrations with different ampl... more Mechanical faults, usages, slackness's, cause different noises and vibrations with different amplitude and frequency against the normal sound and movement of the equipment. The vibration transducers, accelerometers and microphone are used for noise and/or sound and vibration detection with fault detection purpose. Vibration transducers and accelerometers have three functioning domain, if the input frequency is les then the resonant frequency of the sensor it is working as an accelerometer, if the input frequency is higher then the resonant frequency of the sensor it is working as vibrometer. Detecting and analyzing the signal of the transducer, amplitude and spectral analyzing, we can detect usages, slackness and forces which act and produce the fault. Analyzing the output signal of the sensor and compare with a base signal or with nominal values mechanical faults can be detect in functioning time without stopping and to take to pieces the equipment. It is an undestroyed method to find out the functioning problems. In this paper are presented simple transfer functions for two cases, if the mechanical system is vibrating and if through the base is transmitted a vibration to the system. The system behavior is analyzed in Matlab surround the natural frequency of the system. The amplitude and phase modification can be used for signal analysis and fault detection.
Proceedings of 2012 IEEE International Conference on Automation, Quality and Testing, Robotics, 2012
This paper presents an angular positioning system to rotate a web camera. These systems are used ... more This paper presents an angular positioning system to rotate a web camera. These systems are used in security systems for supervision. The controller for the positioning system is developed around a microcontroller PIC 18F4455 type. To follow the response of the controller a virtual instrument was developed in LabWindows/CVI. From the front panel can be set two function modes the
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Papers by Katalin Agoston