This paper presents steps in designing dimensions of antenna and feed in axisymmetrical Cassegrain Antennas. Corrugated conical horns are used as feeds in applications with circular polarization. In the initial design steps, diameter of the main reflector is determined considering communication link budget, then feed dimensions are designed to create optimum aperture efficiency. In the last step of design, considering feed dimensions and the amount of its center phase displacements with respect to its aperture plane, dimensions of subreflector is determined to avoid additional blockage. To illustrate the procedure, an applicative design example is presented in X-band.
The machines subjected to inter-turn short circuit fault can be diagnosed through the characteristic patterns caused by inter-turn short circuit fault components in the DWT analysis by using the stator phase currents.
Everywhere DC motors are used in large applications, the use of drives are very necessary for the smooth running and operating of these motors. The DC motor drives are used mainly for good speed regulation, frequent starting, braking and reversing.
The machines subjected to inter-turn short circuit fault can be diagnosed through the characteristic patterns caused by inter-turn short circuit fault components in the DWT analysis by using the stator phase currents.
Everywhere DC motors are used in large applications, the use of drives are very necessary for the smooth running and operating of these motors. The DC motor drives are used mainly for good speed regulation, frequent starting, braking and reversing.
An induction is an AC electric motor in which the electric current in the rotor needed to produce torque is obtained by electromagnetic induction from the magnetic field of the stator winding. An induction motor therefore does not require mechanical commutation, separate-excitation or self-excitation for all or part of the energy transferred from stator to rotor, as in universal, DC and large synchronous motors. An induction motor's rotor can be either wound type or squirrel-cage type.
V/F control of Induction Motor - Variable voltage and Variable frequencyCitharthan Durairaj
This presentation describes Principle of Variable voltage and Variable frequency- the open loop & closed loop Voltage/Frequency (V/F) control of Induction motor with torque speed characteristics -
Speed control of Three phase Induction motor using AC voltage regulatorShivagee Raj
The role of AC Voltage Regulator in speed control of three phase Induction Motor is to vary the supply voltage which in turn, changes the speed of motor .
CONTENT
Starting Of Induction Motor
Starters
Types Of Starter For 3-ph Induction Motors
Starting Of Slip Ring Induction Motor
D.O.L.(Direct On Line) starter
Star-delta Starter
Auto Transformer Starter
Difference Between DOL/Star Delta/ Autotransformer
Induction Motors Faults Detection Based on Instantaneous Power Spectrum Analy...IDES Editor
A method of induction motor diagnostics based on
the analysis of three-phase instantaneous power spectra has
been offered. Its implementation requires recalculation of
induction motor voltages, aiming at exclusion from induction
motor instantaneous three-phase power signal the component
caused by supply mains dissymmetry and unsinusoidality. The
recalculation is made according to the motor known
electromagnetic parameters, taking into account the
electromotive force induced in stator winding by rotor currents.
The results of instantaneous power parameters computation
proved efficiency of this method in case of supply mains voltage
dissymmetry up to 20%. The offered method has been tested
by experiments. Its applicability for detection of several stator
and rotor winding defects appeared in motor simultaneously
has been proved. This method also makes it possible to
estimate the extent of defects development according to the
size of amplitudes of corresponding harmonics in the spectrum
of total three phase power signal.
FAULT DETECTION AND DIAGNOSIS OF INDUCTION MACHINE WITH ON-LINE PARAMETER PR...Sheikh R Manihar Ahmed
Today all instrumentation system pertaining to industrial process controls as well as domestic application involve automatic fault finding facility. This facility detects the faulty condition of the system and draws operator’s attention towards it enabling him to take suitable remedial action to ensure proper operation of the system. The main purpose of all FDI method is to monitor the system operations and in case of faults accommodate the source of faults so that timely corrective actions are taken. Fault detection simply involves a decision based on the monitored data as to whether there is a fault or the system is running normally. Fault isolation is then executed to identify the type and location of a fault after the fault detection has triggered an alarm so that corrective actions can be made. These two steps are known as Fault Detection and Isolation. Fault diagnosis is referred to as the combination of fault detection, identification and isolation. One such method of annunciation in which activation of visual or mechanical variable takes place when a removed switch or device has been activated as a result of fault in certain system, an audio alarm may also be associated with annunciations. This FDI system is defined and the existing technique to detect & isolate the fault with on-line parameter programming facility. The main advantage of the proposed approach of Control System based fault detection and isolation is its low cost. Low cost in terms of components used makes affordable in terms of easy handling and maintenance and various sensors can be used to give different types of input signals to circuit. An additional advantage is that the real time system still works when the host crashes, the matter that increases the reliability of the system & Data-logging facility can also be provided. A data-logger captures any measurement values which can be represented by a voltage. Nowadays, sensors and transducers are available for, practically, any physical quantity. The function of data-logger is to capture and store a specified number of specified number of sensor measurement values at predefined intervals and transfer the data including date and time to a PC in the form of file.
An induction is an AC electric motor in which the electric current in the rotor needed to produce torque is obtained by electromagnetic induction from the magnetic field of the stator winding. An induction motor therefore does not require mechanical commutation, separate-excitation or self-excitation for all or part of the energy transferred from stator to rotor, as in universal, DC and large synchronous motors. An induction motor's rotor can be either wound type or squirrel-cage type.
V/F control of Induction Motor - Variable voltage and Variable frequencyCitharthan Durairaj
This presentation describes Principle of Variable voltage and Variable frequency- the open loop & closed loop Voltage/Frequency (V/F) control of Induction motor with torque speed characteristics -
Speed control of Three phase Induction motor using AC voltage regulatorShivagee Raj
The role of AC Voltage Regulator in speed control of three phase Induction Motor is to vary the supply voltage which in turn, changes the speed of motor .
CONTENT
Starting Of Induction Motor
Starters
Types Of Starter For 3-ph Induction Motors
Starting Of Slip Ring Induction Motor
D.O.L.(Direct On Line) starter
Star-delta Starter
Auto Transformer Starter
Difference Between DOL/Star Delta/ Autotransformer
Induction Motors Faults Detection Based on Instantaneous Power Spectrum Analy...IDES Editor
A method of induction motor diagnostics based on
the analysis of three-phase instantaneous power spectra has
been offered. Its implementation requires recalculation of
induction motor voltages, aiming at exclusion from induction
motor instantaneous three-phase power signal the component
caused by supply mains dissymmetry and unsinusoidality. The
recalculation is made according to the motor known
electromagnetic parameters, taking into account the
electromotive force induced in stator winding by rotor currents.
The results of instantaneous power parameters computation
proved efficiency of this method in case of supply mains voltage
dissymmetry up to 20%. The offered method has been tested
by experiments. Its applicability for detection of several stator
and rotor winding defects appeared in motor simultaneously
has been proved. This method also makes it possible to
estimate the extent of defects development according to the
size of amplitudes of corresponding harmonics in the spectrum
of total three phase power signal.
FAULT DETECTION AND DIAGNOSIS OF INDUCTION MACHINE WITH ON-LINE PARAMETER PR...Sheikh R Manihar Ahmed
Today all instrumentation system pertaining to industrial process controls as well as domestic application involve automatic fault finding facility. This facility detects the faulty condition of the system and draws operator’s attention towards it enabling him to take suitable remedial action to ensure proper operation of the system. The main purpose of all FDI method is to monitor the system operations and in case of faults accommodate the source of faults so that timely corrective actions are taken. Fault detection simply involves a decision based on the monitored data as to whether there is a fault or the system is running normally. Fault isolation is then executed to identify the type and location of a fault after the fault detection has triggered an alarm so that corrective actions can be made. These two steps are known as Fault Detection and Isolation. Fault diagnosis is referred to as the combination of fault detection, identification and isolation. One such method of annunciation in which activation of visual or mechanical variable takes place when a removed switch or device has been activated as a result of fault in certain system, an audio alarm may also be associated with annunciations. This FDI system is defined and the existing technique to detect & isolate the fault with on-line parameter programming facility. The main advantage of the proposed approach of Control System based fault detection and isolation is its low cost. Low cost in terms of components used makes affordable in terms of easy handling and maintenance and various sensors can be used to give different types of input signals to circuit. An additional advantage is that the real time system still works when the host crashes, the matter that increases the reliability of the system & Data-logging facility can also be provided. A data-logger captures any measurement values which can be represented by a voltage. Nowadays, sensors and transducers are available for, practically, any physical quantity. The function of data-logger is to capture and store a specified number of specified number of sensor measurement values at predefined intervals and transfer the data including date and time to a PC in the form of file.
AC Induction motor (IM) are used as actuators in many industrial processes. Although IMs are reliable, they are subjected to some undesirable stresses, causing faults resulting in failure. Monitoring of an IM is a fast emerging technology for the detection of initial faults. It avoids unexpected failure of an industrial process. Monitoring techniques can be classified as the conventional and the digital techniques.
1.1 PROTECTION SCHEME OF INDUCTION MOTOR
Classical monitoring techniques for three-phase IMs are generally provided by some combination of mechanical and electrical monitoring equipment. Mechanical forms of motor sensing are also limited in ability to detect electrical faults, such as stator insulation failures. In addition, the mechanical parts of the equipment can cause problems in the course of operation and can reduce the life and efficiency of a system.
It is well known that IM monitoring has been studied by many researchers and reviewed in a number of works. Reviews about various stator faults and their causes, and detection techniques, latest trends, and diagnosis methods supported by the artificial intelligence, the microprocessor, the computer and other techniques in monitoring unbalanced voltage inter turn faults, stator winding temperature and microcontroller based digital protectors have been recently studied subjects. In these, while one or two variables were considered together to protect the IMs, the variables of the motor were not considered altogether. Measurements of the voltages, currents, temperatures, and speed were achieved and transferred to the computer for final protection decision.
A programmable integrated circuit (PIC) based protection system has been introduced using Microprocessors and the solutions of various faults of the phase currents, the phase voltages, the speed, and the winding temperatures of an IM occurring in operation have been achieved with the help of the microcontroller, but these electrical parameters have not been displayed on a screen.
Nowadays, the most widely used area of programmable logic controller (PLC) is the control circuits of industrial automation systems. The PLC systems are equipped with special I/O units appropriate for direct usage in industrial automation systems. The input components, such as the pressure, the level, and the temperature sensors, can be directly connected to the input. The driver components of the control circuit such as contactors and solenoid valves can directly be connected to the output.
A Wavelet Based fault Detection of Induction Motor: A Reviewijsrd.com
This paper presents a review of the researches done on fault detection and tolerant control , main aim of the fault tolerant control and fault detection of induction motor is used the wavelet transform. Wavelet transform is much better tool for the fault diagnosis point of view and a overview of the wavelet types (continuous and discrete), machine faults detection methods and their validation. The software, generality of codes, one dimensional and two dimensional DWT and frequency characteristics components of healthy as well as faulty induction motor has explained. So Finally, stator short winding , shaft fault, bearing fault ,rotor broken bar and open winding are taken as a case study to show the better diagnosis of fault by using wavelet techniques.
Mems Based Motor Fault Detection in Windmill Using Neural NetworksIJRES Journal
Today wind turbine technology is one of the fastest growing power generation technologies operating in large numbers at harsh and difficult environment sites and it is difficult to monitor each and every windmill separately. There are times when faults occur in motors of windmills are not detected in earlier stage and we come to know about damage when motor gets fully damaged. Here we using wireless monitoring based on MEMS accelerometer sensor which senses the vibrations occurring in the motor and based on the severity of vibrations, sensor sends the data to the controlling unit to take further action. Neural network based work is included to get the accurate and precise vibratory signals to detect fault at a very early stage to avoid full damage to the motor.
Dynamic Simulation of Induction Motor Drive using Neuro Controlleridescitation
Induction Motors are widely used in Industries, because of the low maintenance
and robustness. Speed Control of Induction motor can be obtained by maximum torque and
efficiency. Apart from other techniques Artificial Intelligence (AI) techniques, particularly
the neural networks, improves the performance & operation of induction motor drives. This
paper presents dynamic simulation of induction motor drive using neuro controller. The
integrated environment allows users to compare simulation results between conventional,
Fuzzy and Neural Network controller (NNW).The performance of fuzzy logic and artificial
neural network based controller's are compared with that of the conventional proportional
integral controller. The dynamic Modeling and Simulation of Induction motor is done using
MATLAB/SIMULINK and the dynamic performance of induction motor drive has been
analyzed for artificial intelligent controller.
Energy Efficient Control of three-Phase Induction Motorijcoa
This paper presents a review of the developments in the field of efficiency optimization of three-phase induction motor through optimal control and design techniques. Optimal control covers both the broad approaches namely, loss model control (LMC) and search control (SC). Optimal design covers the design modifications of materials and construction in order to optimize efficiency of the motor. The use of Artificial Intelligence (AI) techniques such as artificial neural network (ANN), fuzzy logic, expert systems and nature inspired algorithms (NIA), Genetic algorithm and differential evolution in optimization are also included in this paper.
Maintenance Methodology & Systems in Manufacturing : Operations ReserchRenzil D'cruz
Project on Maintenance Methodology & Systems in Manufacturing for subject of Operations Research which covers
Functions and Performance Standards:
Failure Situations
RCM
Manufacturing processes
• Casting
• Moulding
• Forming
• Machining
• Joining
• Rapid manufacturing
• Other trades
Direct Torque Control (DTC) of Induction Motor drive has quick torque response without complex orientation transformation and inner loop current control. DTC has some drawbacks, such as the torque and flux ripple. The control scheme performance relies on the accurate selection of the switching voltage vector. This proposed simple structured neural network based new identification method for flux position estimation, sector selection and stator voltage vector selection for induction motors using direct torque control (DTC) method. The ANN based speed controller has been introduced to achieve good dynamic performance of induction motor drive. The Levenberg-Marquardt back-propagation technique has been used to train the neural network. Proposed simple structured network facilitates a short training and processing times. The stator flux is estimated by using the modified integration with amplitude limiter algorithms to overcome drawbacks of pure integrator. The conventional flux position estimator, sector selector and stator voltage vector selector based modified direct torque control (MDTC) scheme compared with the proposed scheme and the results are validated through both by simulation and experimentation.
Network analysis methods for assessment & measurementPatti Anklam
Presentation slides for a webinar produced by the Leadership Learning Community. Full audio is available on their site, at http://www.leadershiplearning.org/blog/eleanor-cooney/2012-12-17/2013-webinar-network-analysis-snaona-methods-assessment-measurement
Computer Science
Active and Programmable Networks
Active safety systems
Ad Hoc & Sensor Network
Ad hoc networks for pervasive communications
Adaptive, autonomic and context-aware computing
Advance Computing technology and their application
Advanced Computing Architectures and New Programming Models
Advanced control and measurement
Aeronautical Engineering,
Agent-based middleware
Alert applications
Automotive, marine and aero-space control and all other control applications
Autonomic and self-managing middleware
Autonomous vehicle
Biochemistry
Bioinformatics
BioTechnology(Chemistry, Mathematics, Statistics, Geology)
Broadband and intelligent networks
Broadband wireless technologies
CAD/CAM/CAT/CIM
Call admission and flow/congestion control
Capacity planning and dimensioning
Changing Access to Patient Information
Channel capacity modelling and analysis
Civil Engineering,
Cloud Computing and Applications
Collaborative applications
Communication application
Communication architectures for pervasive computing
Communication systems
Computational intelligence
Computer and microprocessor-based control
Computer Architecture and Embedded Systems
Computer Business
Computer Sciences and Applications
Computer Vision
Computer-based information systems in health care
Computing Ethics
Computing Practices & Applications
Congestion and/or Flow Control
Content Distribution
Context-awareness and middleware
Creativity in Internet management and retailing
Cross-layer design and Physical layer based issue
Cryptography
Data Base Management
Data fusion
Data Mining
Data retrieval
Data Storage Management
Decision analysis methods
Decision making
Digital Economy and Digital Divide
Digital signal processing theory
Distributed Sensor Networks
Drives automation
Drug Design,
Drug Development
DSP implementation
E-Business
E-Commerce
E-Government
Electronic transceiver device for Retail Marketing Industries
Electronics Engineering,
Embeded Computer System
Emerging advances in business and its applications
Emerging signal processing areas
Enabling technologies for pervasive systems
Energy-efficient and green pervasive computing
Environmental Engineering,
Estimation and identification techniques
Evaluation techniques for middleware solutions
Event-based, publish/subscribe, and message-oriented middleware
Evolutionary computing and intelligent systems
Expert approaches
Facilities planning and management
Flexible manufacturing systems
Formal methods and tools for designing
Fuzzy algorithms
Fuzzy logics
GPS and location-based app
AC drives are employed in process industries for varying applications resulting in a wide range of ratings. The entire process industry has seen a paradigm shift from manual to automated systems. The major factor contributing to this is the advanced power electronics technology enabling power electronic drives for smooth control of electric motors. Induction motors are most commonly used in industries. Faults in the power electronic circuits may occur periodically. These faults often go unnoticed as they rarely cause a complete shutdown and the fault levels may not be large enough to lead to a breakdown of the drive. An early detection of these faults is required to prevent their escalation into major faults. The diagnostic tool for detection of faults requires real time monitoring of the entire drive. In this work, detailed investigation of different faults that can occur in the power electronic circuit of an industrial drive is carried out. Analysis and impact of faults on the performance of the induction motor is presented. A real time monitoring platform is proposed to detect and classify the fault accurately using machine learning. A diagnostic tool also is developed to display the severity and location of the fault to the operator to take corrective measures.
Many technologies are introduced in monitoring the fault occurrence in the electric motors used in industrial applications. Sound Accusation, current signature analysis, and vibration based motor fault detection systems are widely used in present years. From all these methods analyzing the motor vibration pattern produces more accuracy in finding an occurrence of different faults in the electric motor. The frequency of vibration generated by the MEMS vibration sensor differs for rotor, stator and bearing faults. The signal generated is analyzed using three important techniques namely wavelet analysis, Dyadic Transformation, and Adaptive Neuro-Fuzzy Inference System(WAD Technique). Hardware with ARM microcontroller and ADXL MEMS vibration sensor was used to perform signal acquisition, and the generated signal is processed using the MATLAB software, and the speed of the motor is controlled based on the processed result. The performance of the system with all three algorithms was recorded, and the efficiency of the system is compared.
Design of Data Aquistion interface circuit used in Detection Inter-turn Fault...IJERA Editor
A commitment to condition monitoring involves the operators of plant in the conduct of a range of activities. These activities may be complicated in nature and indeed may often be performed automatically under computer control. They can, however, always be down into a relatively small number of easily identifiable functional tasks. This makes it much easier to identify the common elements of machine condition monitoring schemes .The Motor Current Signature Analysis (MCSA) is considered the most popular fault detection method now a day because it can easily detect the common machine fault such as turn to turn short circuit . The present paper discusses the fundamentals of Motor Current Signature Analysis (MCSA) plus condition monitoring of the induction motor using MCSA. A proposed interface circuit design and application will be further explain in this paper, the implemented monitoring unit circuit also illustrated, see appendix A. Artificial neural networks are extensively used for speed, torque estimation, and solid state drive control in both DC and AC machines. Two scenarios presented in this paper, first ten turns assume to be shorted, and in the second thirty turns shorted to show the difference in the amplitude of frequencies at each case. Finally artificial intelligent techniques are increasingly used for condition monitoring and fault detection of machines. This paper present. An improvement in three-phase squirrel-cage induction motor stator inter-turn fault detection and diagnosis based on a neural network approach is presented.
Detection of Broken Bars in Three Phase Squirrel Cage Induction Motor using F...Dr.NAGARAJAN. S
Finite element method is more precise than the winding function approach, as it is based on the actual geometry of the machine and the machine model can easily be modified in order to study the effect of faults on the machine’s performance. Accurate models of the machine under healthy and faulty conditions are developed. This paper presents simulations of broken bars detection in a three phase squirrel cage induction motor under no load, half load and full load conditions for two and eight broken bars. The analysis is done using MagNet.
Novel setting and design of relay for protection of 3 phase induction motor u...eSAT Journals
Abstract
This paper is designed to protect an Induction Motor from different types of abnormalities. Providing protection for motors is very important in industries, power plants etc. such that production is not hampered owing to failure of any motor. Purpose of motor protection is to limit the effect of disturbances and stress factors to a safe level. If a motor failure takes place, the protection is needed to disconnect the motor from the supply network in due time. Here we have described different abnormal conditions in three phase induction motors and designed a protective scheme to protect it from different abnormalities. We have also described the method which shows how to set electromagnetic relay for large motor and also described the same method in case of numerical relay. Here we have shown one of the faulty condition with the help of PSCAD (student version).
Keywords: Induction motor, Relay, PSCAD student version.
Improved Rotor Speed Brushless DC Motor Using Fuzzy Controllerijeei-iaes
A brushless DC (BLDC) Motors have advantages over brushed, Direct current (DC) Motors and , Induction motor (IM). They have better speed verses torque characteristics, high dynamic response, high efficiency, long operating life, noiseless operation, higher speed ranges, and rugged construction. Also, torque delivered to motor size is higher, making it useful in application where space and weight are critical factors. With these advantages BLDC motors find wide spread application in automotive appliance, aerospace medical, and instrumentation and automation industries This paper can be seen as fuzzy controllers compared to PI control BLDC motor rotor speed has improved significantly and beter result can be achieve.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Detection of internal and external faults of single-phase induction motor usi...IJECEIAES
The main aim of this work is to analyze the input current waveform for a single-phase induction capacitor-run motor (SIMCR) to detect the faults. Internal and external faults were applied to the SIMCR and the current was measured. An armature (broken rotor bar) and bearing faults were applied to the SIMCR. A microcontroller was used to record the motor current signal and MATLAB software was used to analyze it with the different types of fault with varying load operations. Various values of the running capacitor were used to investigate the effect of these values on the wave-current shape. Total harmonic distortion (THD) for the voltage and current was measured. A deep demonstration of the experimental results was also provided for a better understanding of the mechanisms of bearing and armature faults (broken rotor bars) and the vibration was recorded. Spectral and power analyses revealed the difference in total harmonic distortion. The proposed method in this paper can be used in various industrial applications and this technique is quite cheap and helps most of the researchers and very effectual.
Similar to Induction motor fault diagnosis by motor current signature analysis and neural network techniques (20)
Performance of Wideband Mobile Channel with Perfect Synchronism BPSK vs QPSK ...Editor Jacotech
Direct-sequence code-division multiple access (DS-CDMA) is
currently the subject of much research as it is a promising
multiple access capability for third and fourth generations
mobile communication systems. The synchronous DS-CDMA
system is well known for eliminating the effects of multiple
access interference (MAI) which limits the capacity and
degrades the BER performance of the system. In this paper,
we investigate the bit error rate (BER) performance of a
synchronous DS-CDMA system over a wideband mobile
radio channel. The BER performance is affected by the
difference in path length ΔL and the number of arriving
signals N. Furthermore, the effect of these parameters is
examined on the synchronous DS-CDMA system for different
users’ number as well as different processing gain Gp. In this
environment and under the above conditions the performances
of the BPSK (Binary Phase Shift Keying) and the QPSK
(Quadrature Phase Shift Keying) modulations are compared.
The promising simulation results showed the possibility of
applying this system to the wideband mobile radio channel.
MOVIE RATING PREDICTION BASED ON TWITTER SENTIMENT ANALYSISEditor Jacotech
With microblogging platforms such as Twitter generating
huge amounts of textual data every day, the possibilities of
knowledge discovery through Twitter data becomes
increasingly relevant. Similar to the public voting mechanism
on websites such as the Internet Movie Database (IMDb) that
aggregates movies ratings, Twitter content contains
reflections of public opinion about movies. This study aims to
explore the use of Twitter content as textual data for
predicting the movie rating. In this study, we extract number
of tweets and compiled to predict the rating scores of newly
released movies. Predictions were done with the algorithms,
exploring the tweet polarity. In addition, this study explores
the use of several different kinds of tweet classification
Algorithm and movie rating algorithm. Results show that
movie rating developed by our application is compared to
IMDB and Rotten Tomatoes.
Non integer order controller based robust performance analysis of a conical t...Editor Jacotech
The design of robust controller for any non linear process is a
challenging task because of the presence of various types of
uncertainties. In this paper, various design methods of robust
PID controller for the level control of conical tank are
discussed. Uncertainties are of different types, among that
structured uncertainty of 30% is introduced to the nominal
plant for analysing the robustness. As a first step, the control
of level is done by using conventional integer order controller
for both nominal and uncertain system. Then, the control is
done by means of Fractional Order Proportional Integral
Derivative (FOPID) controller for achieving robustness. With
the help of time series parameters, a comparison is made
between conventional PID and FOPID with respect to the
simulated output using MATLAB and also analyzed the
robustness.
FACTORS CAUSING STRESS AMONG FEMALE DOCTORS (A COMPARATIVE STUDY BETWEEN SELE...Editor Jacotech
It is an important task of working women to handle two
important tasks. Balancing these two roles at home and
work is very challenging task and causes stress at different
levels. Different dimension of working women’s life
involves in evolving the stress in working women’s life.
These stresses cause the imbalance at the front of and
handling family responsibility. In the current scenario,
doctors face many stressors that are peculiar to the medical
profession and doctors are required to have more
competencies than before in diagnosis ongoing
management of medical conditions. This means increased
responsibilities which may contribute to stress. Stress
experienced at work can have adverse outcomes for the
well-being of individual employees and organization as
whole. My study is focusing on identifying the factors
causing stress among female doctors working for public
and private hospitals and their stress levels associations
with respect to sector. A sample of 300 female doctors
from urban area participated in this study. Out of this, 150
each are from public and private hospitals respectively. A
self-made standardized tool was administered based on five
point scale. Results indicates that the values were found to
be 0.000 in all the cases except, psychosomatic problems
(0.004) which is lesser than (0.05) p-value resulting into
rejection of null hypotheses , consequently revealing an
association between sector of female doctors and stress due
to workload, working condition, physical exertion,
emotional exhaustion, job security, organizational support,
work family conflict, family adjustment, task demands,
psychosomatic problems, patient’s expectation and working
hours.
ANALYSIS AND DESIGN OF MULTIPLE WATERMARKING IN A VIDEO FOR AUTHENTICATION AN...Editor Jacotech
Watermarking technique be employ instance & for a second time for
validation and protection of digital data (images, video and audio
files, digital repositories and libraries, web publishing). It is helpful
to copyright protection and illegal copying of digital data like video
frames and making digital data more robust and imperceptible. With
the advent of internet, creation and delivery of digital data has grown
many fold. In that Scenario has to need a technique for transferring
digital data securely without changing their originality and
robustness. In this paper proposed a plan of latest watermarking
method which involves inserting and adding two or more digital data
or pictures in a single video frame for the principle of protection and
replicate the similar procedure for N no video frames for
authentication of entire digital video. After that digital video is
encrypted and decrypted by using motion vector bit-xor encryption
and decryption technique.
The Impact of Line Resistance on the Performance of Controllable Series Compe...Editor Jacotech
In recent years controllable FACTS devices are increasingly
integrated into the transmission system. FACTS devices that
provide series control such as Controllable Series Compensator
(CSC) has significant effect on the voltage stability of Electric
Power system. In this work impact of line resistance on the
performance of CSC in a single-load infinitive-bus (SLIB)
model is investigated. The proposed framework is applied to
SLIB model and obtained results demonstrates that line
resistance has considerable effect on voltage stability limits and
performance of CSC.
Security Strength Evaluation of Some Chaos Based Substitution-BoxesEditor Jacotech
Recently, handful amount of S-boxes, using the various
methods such as affine transformations, gray coding,
optimization, chaotic systems, etc, have been suggested. It is
prudent to use cryptographically strong S-boxes for the design
of powerful ciphers. In this paper, we sampled some widely
used 8×8 S-boxes which are recently synthesized and security
analysis and evaluation is executed to uncover the best
candidate(s). The performance analysis is exercised against
the crucial measures like nonlinearity, linear approximation
probability, algebraic immunity, algebraic complexity,
differential uniformity. These parameters are custom selected
because their scores decide the security strength against
cryptographic assaults like linear cryptanalysis, algebraic
attacks, and differential cryptanalysis. The anticipated
analysis in this work facilitates the cryptographers, designers,
researchers to choose suitable candidate decided over many
parameters and can be engaged in modern block encryption
systems that solely rely on 8×8 S-box. Moreover, the analysis
assists in articulating efficient S-boxes and to evaluate the
attacks resistivity of their S-boxes.
Traffic Detection System is an Android application that aims at determining the behavior of traffic in a particular location. It calculates the speed of the vehicle and the level of congestion or the amount of traffic is determined on the basis of the values of sensors. If any such obstruct found, then the driver is provided an option to send messages regarding high traffic to his/her friends. After a distinct number of repeated low speed and breaks, the location of the vehicle (latitude and longitude) send to a pre-specified contact (selected in case of traffic congestion) through an SMS. This application uses the features of the Global positioning system. The Latitude, as well as the longitude of the location where traffic jams are formed, is sent to the friends of the user. The Goggle map of the location also sends to the friends. It uses the SMS Manager a functionality of Android. The friends receiving the messages will thereby avoid taking the congested route and hence the level of traffic on the congested road will decrease, and the friends will reach the destination in comparatively less time.
Performance analysis of aodv with the constraints of varying terrain area and...Editor Jacotech
Mobile Ad Hoc Networks (MANETs) are wireless networks,
where there is no requirement for any infrastructure support to
transfer data packets between mobile nodes. These nodes
communicate in a multi-hop mode; each mobile node acts
both as a host and router. The main job of Quality of Service
(QoS)[1][2] routing in MANETs is to search and establish
routes among different mobile nodes for satisfying QoS
requirements of wireless sensor networks as PDR, Average
end-to-end delay, Average Throughput. The QoS routing
protocols efficient for commercial, real-time and multimedia
applications are in demand for day to day activities[2].
Modeling of solar array and analyze the current transient response of shunt s...Editor Jacotech
Spacecraft bus voltage is regulated by power
conditioning unit using switching shunt voltage regulator having
solar array cells as the primary source of power. This source
switches between the bus loads and the shunt switch for fine
control of spacecraft bus voltage. The effect of solar array cell
capacitance [5][6] along with inductance and resistance of the
interface wires between solar cells and power conditioning
unit[1], generates damped sinusoidal currents superimposed on
the short circuit current of solar cell when shunted through
switch. The peak current stress on the shunt switch is to be
considered in the selection of shunt switch in power conditioning
unit. The analysis of current transients of shunt switch in PCU
considering actual spacecraft interface wire length by
illumination of solar panel (combination of series and parallel
solar cells) is difficult with hardware simulation. Software
simulation by modeling solar cell is carried out for a single string
(one parallel) in Pspice [6]. Since in spacecrafts number of
parallels and interface cable length are variable parameters the
analysis of current transients of shunt switch is carried out by
modeling solar array with the help of solar cell model[6] for the
actual spacecraft condition.
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Induction motor fault diagnosis by motor current signature analysis and neural network techniques
1. Journal of Advanced Computing and Communication Technologies (ISSN: 2347 - 2804)
Volume No. 3 Issue No.1, February 2015
12
12
Index Terms—Condition Monitoring, Fault Diagnosis,
Induction Motor, Neural Network, Signature Analysis.
Abstract—Early detection of faults occurring in three-phase
induction motors can appreciably reduce the costs of
maintenance, which could otherwise be too much costly to repair.
Internal faults in three phase induction motors can result in
significant performance degradation and eventual system
failures. Artificial intelligence techniques have numerous
advantages over conventional Model-based and Signal Processing
fault diagnostic approaches; therefore, in this paper, a soft-
computing system was studied through Neural Network Analysis
to detect and diagnose the stator and rotor faults. The fault
diagnostic system for three-phase induction motors samples the
fault symptoms and then uses a Neural Network model to first
train and then identify the fault which gives fast accurate
diagnostics. This approach can also be extended to other
applications.
I. INTRODUCTION
INDUCTION motors as electrical machines offer most
versatility in industry due to their low cost, ruggedness, low
maintenance, and easy operation and control. Although they
are very reliable, they may encounter different types of
failures/faults. These faults may be inherent to the machine
itself or due to operating conditions of the motor. Mechanical
or electrical forces are mostly responsible for failures. A
variety of machine faults have been studied in the literature [1,
2] such as winding faults, unbalanced stator and rotor
parameters, broken rotor bars, eccentricity and bearing faults.
Recently soft computing techniques such as expert system,
neural network, fuzzy logic, etc. have been employed [3, 4, 5]
to correctly interpret the fault data with proper analysis. Their
1
Mr. Subir Bhattacharyya has completed his B.E. and M.E. in Electrical
Engineering from BESU, Shibpur in 1978 and 1981 respectively. He has been
associated with the design & quality assurance departments of various
industries for over 25 years and with teaching for over 10 years. His research
areas include renewable energy, energy audit and condition monitoring of
electrical machines among other things. He is currently the Principal
(Diploma) & Head of Department (EE), NSHM Knowledge Campus,
Durgapur – 713 212.
2
Mr. Deepro Sen has completed his M.E. in Power Engineering from
Jadavpur University, Kolkata. His area of research includes electrical
machines, soft computing techniques and power generation economics.
3
Ms. Shreya Adhvaryyu has completed her M.Tech in Power Systems from
Dr. B.C. Roy Engineering College. Her research areas include electrical
machines, power systems and artificial intelligence systems.
4
Mr. Chiranjib Mukherjee has completed his M.Tech in Power Systems
from Dr. B.C. Roy Engineering College. His research areas include electrical
machines, electrical machine designs and power systems. He is currently
working as an Assistant Professor in the EE department, NSHM Knowledge
Campus, Durgapur – 713 212 with over four years of teaching experience.
improved performance apart from the ease of application and
modification for various machines and fault scenarios make
them extremely popular for diagnostic purposes. The use of
above techniques increases the precision and accuracy of the
monitoring systems. Condition monitoring of electrical
machines and associated drives is a large arena which is inter-
linked with different subjects like signal processing and
intelligent systems, methods of monitoring, and associated
instrumentation.
II. FAULTS IN THREE-PHASE INDUCTION MOTORS
Induction motors are very popular in industry and ruggedly
used. Due to this reason, these types of motors also undergo
various types of faults, mostly of electrical and mechanical
nature. Different types of faults are shown in Fig. 1. They are
short circuits in stator windings, open-circuits in stator
windings, broken rotor bars and broken end rings. The effects
of these faults are various, some of them being unbalanced
stator voltages and currents, torque oscillations, efficiency
reduction, overheating, excessive vibration, and torque
reduction.
This section is focused on four types of induction motor
faults, namely: broken rotor bars, inter-turn short circuits in
stator windings, bearing faults and air – gap eccentricities.
A. Broken Rotor Bars
An induction motor has two parts – stator and rotor. The
rotor has bars with slots for the rotor windings and end rings
to short the ends of the windings. The rotor bars may crack or
break due to a lot of reasons (explained in detail later), which
gives rise to broken rotor bars.
A broken bar causes several effects in induction motors. A
well-known effect of a broken bar is the appearance of the so-
called side-band components in the frequency spectrum of the
stator current. These are found on the left and right sides of the
fundamental frequency component. Consequent speed ripples
caused by the resulting torque pulsations [6] gives rise to the
right side band and the lower side band component is caused
by electrical and magnetic asynchronies in the rotor cage of an
induction motor [7]. The frequencies of these sidebands are
given by:
(1)
where s is the slip in per unit and f is the fundamental
frequency of the stator current (power supply). Other electric
effects of broken bars are used for motor fault classification
purposes including speed oscillations, torque ripples,
Induction Motor Fault Diagnosis by Motor Current
Signature Analysis and Neural Network Techniques
By
Subir Bhattacharyya1
, Deepro Sen2
, Shreya Adhvaryyu3
, Chiranjib Mukherjee4
2. Journal of Advanced Computing and Communication Technologies (ISSN: 2347 - 2804)
Volume No. 3 Issue No.1, February 2015
13
13
instantaneous stator power oscillations, and stator current
envelopes.
Fig. 1. Types of Induction Motor Faults
B. Inter – turn short circuits of stator windings
Short circuits in stator windings are most common in
induction motors. Generally, short circuits in stator windings
occur between turns of one phase, or between turns of two
phases, or between turns of all phases. Moreover, short
circuits between winding conductors and the stator core also
occur. The different types of winding faults are summarized
below as follows:
1) Inter-turn short circuits between turns of the same
phase (Fig. 2a), winding short circuits (Fig. 2b) ,
short circuits between winding and stator core (Fig.
2c and Fig. 2d), short circuits on the connections
(Fig. 2e), and short circuits between phases (Fig. 2f)
are usually caused by voltage transients and abrasion.
2) The winding insulation and consequent complete
windings are short circuited in the event of burning
which are usually caused by motor overloads and
blocked rotor, as well as lower/ higher rated voltage
supplied to the stator. This type of fault can be caused
by frequent starts and rotation reversals. These faults
are shown in Fig. 3a and 3b.
3) Short circuits of the stator windings are also due to
voltage transients as shown in Fig. 3c that can be
caused by the successive reflection resulting from
cable connection between motors and ac drives.
These drives produce extra voltage stress on the
stator windings due to the swings of the voltage
applied to the stator windings. Again, long cable
connections between a motor and an ac drive can
induce motor over voltages.
4) Complete short circuits of one or more phases can
occur because of phase loss, which is caused by an
open fuse, contactor or breaker failure, connection
failure, or power supply failure. Such a fault is shown
in Fig. 3d and 3e.
5) Short circuits in one phase are usually due to an
unbalanced stator voltage, as shown in Fig. 3f.
Voltage imbalance is caused by an unbalanced load
in the power line, anomaly in the connection of the
motor terminals or in the power circuit.
Fig. 2. Typical insulation damage leading to inter-turn short circuit of the
stator windings in three-phase induction motors. (a) Inter-turn short circuits
between turns of the same phase. (b) Winding short circuited. (c) Short
circuits between winding and stator core at the end of the stator slot. (d) Short
circuits between winding and stator core in the middle of the stator slot. (e)
Short circuit at the leads. (f) Short circuit between phases. [Courtesy of
Electromotors WEG SA, Brazil]
Fig. 3. Inter-turn short circuit of the stator winding in three-phase induction
motors. (a) Short circuits in one phase due to motor overload (b) Short circuits
in one phase due to blocked rotor. (c) Inter-turn short circuits are due to
voltage transients. (d) Short circuits in one phase due to a phase loss in a Y-
connected motor. (e) Short circuits in one phase due to a phase loss in a delta-
connected motor. (f) Short circuits in one phase due to an unbalanced stator
voltage. [Courtesy of Electromotors WEG SA, Brazil]
3. Journal of Advanced Computing and Communication Technologies (ISSN: 2347 - 2804)
Volume No. 3 Issue No.1, February 2015
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14
C. Bearing Faults
Bearing faults account for almost half of all motor failures.
Although motor bearings may cost between a tenth of the
actual cost of the motor, but the costs involved in stalled
production combine to make bearing failure rather expensive.
Ball-bearing related defects can be categorized as ball defects,
outer bearing race defects and inner bearing race defects.
A bearing has different stresses acting upon it, leading to
excessive audible noise, uneven running, reduction in working
precision, and mechanical vibrations and as a result, increased
wear and tear. More than twenty years ago, few bearing
failures were electrically induced but at the beginning of the
90’s a study showed that bearing failures are about 12 times as
common in converter – fed motors as in direct on – line
motors. However mechanical issues remain the major cause of
bearing failure.
D. Air – gap eccentricities
Any mechanical fault leads to stator and rotor imbalances.
This is due to the development of non-uniformity of the air-
gap, which is a result of the rotor and stator axes falling out of
synchronism. Of course, this eccentricity may occur during the
process of manufacturing and fixing the rotor. There is
different eccentricity including static, dynamic and mixed.
When the static eccentricity occurs, the rotor rotational axis
coincides with its symmetrical axis, but has displacement with
the stator symmetrical axis. In this case, the air gap around the
rotor misses its uniformity, but it is invariant with time. Fig.
4a shows the cross section of the proposed induction motor
and Fig. 4b exhibits the corresponding figure with static
eccentricity.
In practice, the air gap magnetic field can be measured by a
small search coil where a sensor is fixed in the air gap and the
noise effect upon the sent signals is eliminated. Winding
function method (WFM), equivalent magnetic circuit method
(MECM) and finite element method (FEM) are the three most
popular methods used for modelling, analysing and diagnosing
induction motor faults.
(a) (b)
Fig. 4. (a) Cross-section of proposed induction motor. (b) Cross-section of
stator and rotor positions with static eccentricity.
III. INDUCTION MOTOR FAULT DIAGNOSTIC METHODS
In this section, a discussion of the features of induction motors
used in the diagnostic and monitoring methods to classify
motor faults is presented. The method classifies broken rotor
bars and inter-turn short circuits in stator windings and also
identifies the fault severity. The most commonly used
traditional diagnosis methods are the motor current signature
analysis (MCSA) [8], wavelet analysis [9], which require
complicated signal pre-processing like fast Fourier
transformation (FFT) or wavelet transformation (WT) and
demodulation of the voltage and/or current. Several other
techniques are used which are depicted in Fig. 5.
Normally, Phases A, B, and C are balanced in a healthy
motor, so when the balance is lost, the motor must have a
fault, with absolute phase value difference (APVD) [10] used
to reflect this fault. For example, Table 1 lists experimental
voltage data and Table 2 lists the corresponding APVD for
healthy motor and motor with various faults [10].
The next sub-sections discuss the most common type of
fault detection diagnostic method using the MCSA for broken
rotor bars and application of neural networks for detection of
short circuits in stator windings.
Fig. 5. Types of Fault Diagnosis Techniques of Induction Motor
TABLE I
Voltage data of healthy and faulty motors
Condition Voltage (V)
State Fault
Phase
A
Phase B Phase C
Healthy
State
N/A 129.100 129.400 129.700
Stator
Fault
One phase short circuit 127.825 126.844 128.324
Two phase short circuit 127.420 127.537 126.450
Three phase short circuit 147.027 145.265 149.242
Rotor
Fault
One bar broken 121.008 128.665 127.140
Two bars broken 125.233 132.782 131.071
Three bars broken 123.584 131.571 130.140
TABLE II
APVD of the voltages in healthy and faulty motors
Condition APVD of the Voltage (V) Average APVD
of the voltage
(V)State Fault
Phase
AB
Phase
BC
Phase
CA
Healthy
State
N/A 0.300 0.300 0.600 0.400
Stator
Fault
One phase
short circuit
0.981 0.520 1.501 1.001
Two phase
short circuit
0.117 1.087 0.970 0.725
Three phase
short circuit
1.762 3.977 2.215 2.651
Rotor
Fault
One bar
broken
7.657 1.525 6.132 5.105
Two bars 7.549 1.711 5.838 5.033
4. Journal of Advanced Computing and Communication Technologies (ISSN: 2347 - 2804)
Volume No. 3 Issue No.1, February 2015
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broken
Three bars
broken
7.987 1.431 6.556 5.325
A. Motor Current Signature Analysis (MCSA)
MCSA is a frequently used method for analysing faults of
induction motors. Whenever a fault occurs in a three-phase
induction motor, it is mostly due to broken rotor bars, air-gap
anomalies and stator windings short circuits. As a result of
these faults, various magnetic flux components are produced
in the magnetic circuit of the induction motor. This gives rise
to harmonic components in the line current of the stator, which
is detectable by current transducers and spectrum analysers.
This method is very commonly used in industries and
laboratories and it is very effective and cost efficient. Online
monitoring can also be done by this method, that is, the motor
can be monitored effectively when it is in operation. This
reduces the risk of failure and damage.
Fig. 6 shows a current spectrum which is the result of
broken rotor bars. The frequency sidebands near the main
harmonic can be observed.
Different faults have different characteristics in their fault
patterns, which gives rise to unique current signature patterns.
For detecting the same, a decibel (dB) versus frequency
spectrum is used [11, 12].
The reason for the appearance of the frequencies in the
spectrum will be discussed next.
Fig. 6. Idealized Current Spectrum
In the three-phase induction motor under perfectly balanced
conditions (healthy motor) only a forward rotating magnetic
field is produced, which rotates at synchronous speed,
, where f1 is the supply frequency and p the pole-
pairs of the stator windings. The rotor of the induction motor
always rotates at a speed (n) less than the synchronous speed.
The slip, , is the measure of the slipping back
of the rotor regarding to the rotating field. The slip speed,
is the actual difference in between the
speed of the rotating magnetic field and the actual speed of the
rotor.
The frequency of the rotor currents is called the slip
frequency and is given by:
(2)
The speed of the rotating magnetic field is given by:
(3)
Both the stator and rotor fields are locked together and a
steady torque is produced by the induction motor.
The broken rotor bars in the motor produces a backward
rotating magnetic field apart from the already existing fields,
which rotates at the slip speed with respect to the rotor.
The broken bars of the rotor results in the production of
backward rotating magnetic field, the speed of which, with
respect to the rotor is:
(4)
There is a rotating field now with respect to the stationary
stator winding at:
(5)
which, in terms of frequency, is:
(6)
This means that a rotating magnetic field at that frequency
cuts the stator windings and induces a current at that
frequency ( ). This in fact means that is a twice slip
frequency component spaced 2s down from . Thus speed
and torque oscillations occur at 2s , and this induces an upper
sideband at 2s above .
Classical twice slip frequency sidebands therefore occur at
± 2s around the supply frequency:
(7)
While the lower sideband is specifically due to broken bar, the
upper sideband is due to consequent speed oscillation. In fact,
several papers show that broken bars actually give rise to a
sequence of such sidebands given by equation [3]:
(8)
Therefore the appearance in the harmonic spectrum of the
sidebands frequencies given by (7) or (8) clearly indicates a
rotor fault of the induction machine.
The spectral analysis of the stator current of a 0.5HP, 4-
pole, 50 Hz induction motor [13] shows the results as depicted
in Fig. 7 and Fig. 8.
(a)
5. Journal of Advanced Computing and Communication Technologies (ISSN: 2347 - 2804)
Volume No. 3 Issue No.1, February 2015
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(b)
Fig. 7. (a) Power spectrum of healthy motor under no-load condition (b)
Power spectrum of 30% short stator windings motor under no-load condition
(a)
(b)
Fig. 8. (a) Power spectrum of healthy motor under full-load condition (b)
Power spectrum of 30% short stator windings motor under full-load condition
The above figures show the presence of harmonics in the
motor current in case of short – circuited stator windings. For
no – load, the harmonics due to the faults occur at 25 Hz and
75 Hz (Fig. 7b) and for full – load, the harmonics occur at 27
Hz and 73 Hz (Fig. 8b), whereas these harmonics are totally
absent for a healthy motor, running at either no – load or full –
load (Fig. 7a and Fig. 7b). It can also be noted that with
increased load, the magnitude of fault frequency increases
from about -70dB for no – load (Fig. 7b) to -60dB for full –
load (Fig. 8b) conditions.
B. Neural Network approach for IM fault analysis
This system consists of detection and the location of a fault
on the stator windings of a three phase induction motor by
using the Neural Networks, which is the result of inter-turn
short circuit. The Fig. 9 shows the block diagram of the fault
location procedure in the stator winding of an induction motor.
Fig. 9. Block diagram of the fault location procedure
This process starts with the acquisition of the three line
currents and phase voltages from the induction motor in order
to extract the three phase shift between the line currents and
the phase voltages. The Neural Network is trained to identify
the difference between the NNs inputs and outputs and map a
relationship between them. The training is done on the basis of
line current and phase voltage shifts on three-phase. The NNs
output is zero (0) in healthy condition and one (1) when an
inter-turn short circuit occurs.
There are three inputs of the neural network which is
employed for fault detection. The input is done to the NN after
phase shift. The three outputs vis-à-vis the 3-phase induction
motor is used for reading the result : zero for normal and one
for short circuit fault, if detected [14]. The schematic is shown
in Fig. 9.
The induction motor used for obtaining the following
experimental data is a 2-HP, 400V, 4-pole SRIM. The details
of the motor’s nameplate has been given in Table III.
TABLE III
INDUCTION MOTOR CHARACTERISTICS
Power (HP) 2
Voltage (V) 220 / 400
Current (I) 13.63 / 3.75
Speed (r/min) 1410
Number of poles 4
Number of coils / phase 12
Number of turns per coil 46
Type of stator windings Double layer, Lap
Number of stator slots 36
Fig. 10. (a) NN Output & error for fault on phase A
Fig. 10. (b) NN Output & error for fault on phase B
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Fig. 10. (c) NN Output & error for fault on phase C
A fault occurring in phase A is signified by the output of
that phase to be one and others to be zero. In Fig. 10(a), the
output and percentage error of the NN is shown when fault
occurs in phase A. The error is the calculation error of the NN
in computing the target value. From the figure, we can see that
the difference between the actual and target values is 9.1701 x
10-6
, which implies that the NN is capable enough to detect
phase faults in induction motors.
The output and percentage error, when an inter-turn short
circuit fault occurs on phase B of an induction motor, is shown
in Fig. 10(b). From Fig. 10(b) it is clear that the error, which is
the difference between the target value and the actual output,
is 1.4800×10-2
.
Figs.10(c) depicts the output and percentage error when an
inter-turn short circuit fault occurs on phase C of an induction
motor. When a stator inter-turn fault occurs on phase C then
the output of that phase is one and others are zero. From Fig.
10(c), it is clear that the NN has correctly reproduced the
desired output. The error is 9.0743×10-7
as shown in Fig.10(c).
IV. CONCLUSION & FUTURE SCOPE
The common types of faults and their diagnostic methods
have been investigated in this paper. Various static factors,
such as the load condition, saturation effect, imbalance of
power supply, and motor misalignment can strongly affect the
accuracy and speed of standard motor fault diagnostics. The
statistical data reveals that –
(1) Fault detection using the stator phase current signature is
the simplest and cheapest technique. However, it is
significantly affected by motor loading (some rotor faults
may not be detected at light loads). Hence, it is
recommended to monitor more than one peak to improve
the sensitivity of detection for some fault cases. Also
detection of stator faults is quite difficult because of the
narrow range of change of the detected peaks.
(2) Although some mathematical models have been
developed, designing exact mathematical models for all
possible faults in induction motors is not possible.
Therefore, mathematical model-based diagnosis methods
need to be replaced by mathematical model independent
artificial intelligence (AI)-based methods, such as expert
systems, Neural Networks, fuzzy logic, or various
hybrids. Since the approach is based on test data, expert
knowledge, and experience, the Neural Network can
easily distinguish fault symptoms from static factors. The
hardware-software system can quickly and accurately
diagnose motor faults. The scheme can be used for other
similar applications, such as fault diagnostics of other
types of equipment and even the prognosis.
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