Fault Detection and Protection of Induction Motors Using Sensors ABSTRACT Protection of an induction motor (IM) against possible problems, such as overvoltage, over current, overload, over temperature, and under voltage, occurring in the course of its operation is very important, because it is used intens intensiv ively ely in indust industry ry as an actuat actuator or.. IMs can be protec protected ted usi using ng some some components, such as timers, contactors, voltage, and current relays. This method is known as the classical method that is very basic and involves mechani mechanical cal dynami dynamic c parts. parts. Comput Computer er and progra programma mmable ble logic logic contro controlle llerr (PIC) (PIC) based based protec protectio tion n method methods s have have elimi eliminate nated d most most of the mechani mechanical cal components. However, the computer-based protection method requires an anal analog og-to -to-d -dig igit ital al conv conver ersi sion on (A (ADC DC)) card card,, and the the PL PLCC-bas based ed prot protec ecti tion on method does not visualize the electrical parameters measured. In this study, for IMs, a new protection protection method based on a programm programmable able logic controller controller (PLC) has been introduced. In this method, all contactors, timers, relays, and the conversion card are eliminated. Moreover, the voltages, the currents, the speed, and the temperature values of the motor, and the problems occurred in the the sy syst stem em,, are are moni monito tore red d and warn warnin ing g messa message ges s are are sh show own n on the the computer screen. Experimental results show that the PLC-based protection method developed costs less, provides higher accuracy as well as safe and visual environment compared with the classical, the computer, and the PLCbased protection systems.
INTRODUCTION Ac Induction Motors (IMs) are used as actuators in many industrial processes. Although IMs are reliable, they are subjected to some undesirable stress stresses, es, causing causing faults faults result resulting ing in failur failure. e. Monito Monitorin ring g of an IM is a fast 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. Classical monitoring techniques for for thre threee-ph phas ase e IMs IMs are are gene generrally ally prov provid ided ed by some some comb combin inat atio ion n 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 caus cause e prob proble lems ms in the the cour course se of oper operat atio ion n and and can can redu reduce ce the the life life and and efficiency of a system.
It is well ell know known n that that IM monit onitor oriing has has been been stud studie ied d by many any resea research rchers ers and reviewe reviewed d in a number number of works. works.
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computer, and other techniques in monitoring and protection technologies have have been been presen presented ted.. In other other works, works, ball ball beari bearing ng failur failures, es, speed speed rippl ripple e effe effect ct,, air air gap ecce eccent ntri rici city ty,, broke broken n roto rotorr bars bars,, sh shaft aft speed speed osci oscill llat atio ion, n, damage damaged d beari bearings, ngs, unbalan unbalanced ced voltage voltage,, inter inter turn turn faults, faults, stator stator windin winding g temperatu temperature re and PLC-based PLC-based digital protector protectors s have been recently recently studied studied subj su bjec ects ts.. In thes these e pape papers rs,, whil while e one one or two two vari variabl ables es were were consi conside dere red d together to protect the IMs, the variables of the motor were not considered altoge altogethe ther. r. This This might might cause cause diffic difficult ulties ies in protec protectio tion. n. A comput computer er based based protec protecti tion on system system has been been introd introduce uced. d. Measur Measureme ements nts of the voltage voltages, s, currents & temperatures were achieved and transferred to the computer for final protection decision. In this paper, although all the variables of the motor were were cons consid ider ered ed,, us usage age of an analo analogg-to to-d -dig igit ital al conv conver ersi sion on (A (ADC DC)) card card increases the cost and the size of the system. The solutions of various faults of the phase currents, the phase voltages and the winding temperatures of an IM occurring in operation have been achieved with the help of the PLC; these electrical parameters have been displayed on a screen.
Nowadays, the most widely used area of programmable logic controller (PLC (PLC)) is the the cont contro roll circ circui uits ts of indu indust stri rial al auto automa mati tion on sy syst stem ems. s. The The PL PLC C
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. Many factories use PLC in automation processes to diminish production cost and to increase quality and reliability. There are a few papers published about the control of IMs with PLC. One of them is about power factor controller for a three-phase IM that utilizes a PLC to improve the power factor and to keep its voltage-tofrequency ratio constant over the entire control range. The other paper deals with monitoring control system of the induction motor driven by an inverter and controlled by a PLC providing its high accuracy in speed regulation at constant speed–variable-load operation. Despite the simplicity of the speed control method used, this system presents constant speed for changes in load torque, full torque available over a wider speed range, a very good accuracy in closed-loop speed control scheme.
This paper explains a PLC-based protection and monitoring method for a three-phase induction motor. The new solutions for various faults of the phase currents, the phase voltages and the winding temperatures of an IM occurring in operation have been achieved with the help of a PLC. If only a PLC is used as a protection relay for a system, it costs more. But the use of a PLC can be the right choice if it is considered in an automation system in order not to use extra microprocessor such as a PIC.
BLOCK DIAGRAM
3 Single Phase Supply
Potential Transfor mer
Current Transfor mer
Rectifier
I/V Convert er
Filter
Rectifier & Filter
PLC / PIC Micro Contr oller
Control Unit
Load
APPLICATIONS:Industrial Applications
ADVANTAGES:•
Monitoring of an IM is a fast emerging technology for the detection of initial faults.
•
It avoids unexpected failure of an industrial process
EXISTING SYSTEM:
IMs IMs can can be prot protec ecte ted d us usin ing g some some comp compon onen ents ts,, su such ch as time timers rs,, contactors, voltage, and current relays. This method is known as the classical method that is very basic and involves mechanical dynamic parts. parts. Comput Computer er and progra programma mmable ble integr integrate ated d circui circuitt (PIC) (PIC) based based prot prote ectio ction n metho ethods ds hav have eli elimina minate ted d most of the the mech echani anical cal components.
However, the computer-based protection method requires an analogto-digital conversion (ADC) card, and the PIC-based protection method does not visualize the electrical parameters measured .
PROPOSED SYSTEM:
All contactors, timers, relays, and the conversion card are eliminated.
Moreover, the voltages, the currents, the speed, and the temperature values of the motor, and the problems occurred in the system, are monitored and warning messages are shown on the computer screen
HARDWARE REQUIREMENTS:•
PIC Microcontroller / DELTA PLC
•
Power supply
•
Relays
•
Signal Conditioning Circuit
•
IM
SOFTWARE REQUIREMENTS:•
MP Lab / WPL Soft
•
Cadence
•
MATLAB
OUTPUT:Prototype model Simulation