By far the most commonly used ac motor is the induction motor. An induction motors rotor can be either wound type or squirrel. In an induction motor, torque is equal to the power crossing the air gap divided by the synchronous mechanical speed. Pdf optimal volume and slip of a three phase induction motor. In turn, a current is produced in the rotor bars and shorting ring and another magnetic field is. Slip in induction motor is the relative speed between the rotating magnetic flux and rotor expressed in terms of per unit synchronous speed.
Lecture notes electrical machine ii bee 1401 page 1. The rotor of the slip ring induction motor is also cylindrical or constructed of lamination. No contacts on rotor shaft high powerweight ratio compared to dc motor lower costpower easy to manufacture almost maintenance free, except for bearing and other mechanical parts disadvantages essentially a fixedspeed machine speed is determined by. Motion and temperature heat control are paramount in energy. The slip ring induction motor could be used for industrial wires where variable speed and high starting torque are prime requirements. So, now principle of induction motor right so, the operation of three phase induction. The three phase induction motor is the most widely used electrical motor. Jun 01, 2018 slip in induction motor is the relative speed between the rotating magnetic flux and rotor expressed in terms of per unit synchronous speed. The basic idea of an electric motor is to generate two magnetic fields. You also come to know about the law on which the motor works, the types of field induces on the rotor, and. Slip of induction motor plays an important role in the operation of the induction motor.
Number of poles, frequencies and synchronous induction motor speed. Slip, which varies from zero at synchronous speed and 1 when the rotor is at. Electrical motor electric motor electromagnetic induction. It is a maintenance free, less noisy and efficient motor. As we know, the slip speed is the difference between the synchronous and rotor speed of the induction motor. No slip, no torque because there will be no current in the rotor cage. How do the new ie efficiency classes compare with the old eff efficiency classes. Protection of induction motor relay fuse electrical. This final thesis will mostly be dedicated to induction motors but also to synchronous permanent magnet and reluctance motors. According to the type of rotor, an induction motor is divided into two types.
But the rotor construction differs with respect to the type of motor. To explain clearly when there is relative speed between stator and rotor ample amount of emf is induced in th. If slip is zero then their is no relative speed between stator and rotor. Induction motor 1 induction motor why induction motor im. Squirrel cage motors have a rotor with short circuited bars whereas slipring motors have wound rotors having three windings each connected in star. Today we are going to made available a powerpoint presentation file for all. All we need to do is to keep daxis stator current constant. Slip speed of an ac induction motor is a small difference between the synchronous speed of the rotating magnetic field and actual speed of the rotor, generally measured in rpm. Nov 11, 2017 torque slip characteristics of induction machine pull out torque, breakdown torque, motoring mode, generating mode, breaking mode of induction motors, electric motor torque curve torque speed. Mar 11, 2017 what is slip in an induction motor, how it is calculate and all the details about slip in an induction motor is given in this video watch other videos. More than selection from electrical machine design book. S l r the flux in the singleturn coil on the rotor surface is.
This curve provides us with information about the operation of an induction motor. As we know the speed of induction motor, torque of induction motor, so, the speed of induction motor can be changed by changing synchronous speed or by changing the slip of induction motor and then parameter r2 and x2 are changed then torque remain constant and change in slip is affected in speed control. Three phase slip ring induction motor my tech info. Induction motor equations engn1931f spring 2017 2 let. Concluding, advantage of induction motor is its simple operation, reliability and low cost. An induction motor also known as an asynchronous motor is a commonly used ac electric motor. The construction of a stator is the same for both the squirrel cage and slip ring induction motor. For an induction motor with p polesand f frequency, slip for induction motors a very important parameter is the slip of the motor the slip, s, defines the relative speed difference between synchronous speed and rotor speed and is given by. Induction motor seminar ppt, pdf report study mafia. Slip compensation of induction motor using sensorless control ieice. An induction motor, 3 phase induction motor or asynchronous motor 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. The singlephase induction motor is the most frequently used motor for refrigerators, washing machines, clocks, drills, compressors, pumps, and so forth. A 480v, 60 hz, 6pole, threephase, deltaconnected induction motor has the following parameters. An induction motor can be defined as the ac electric motor device in which a power source fed by the alternating current with the help of a primary winding.
A 3 phase induction motor can be used for different applications with various speed and load requirements. Speed of the rotor of an induction motor is always less than its synchronous speed. In early slipring induction motor drives, power was transferred through the motor to be dissipated in external resistances, connected to the slip ring terminals of the rotor. An electrical motor is a device that has brought about one of the biggest advancements in the fields of engineering and technology ever since the invention. Typical induction motor rotors the magnetic field generated in the stator induces an emf in the rotor bars. But producing goods and services is strongly related to the use of energy in an intelligent way. Slip is defined as difference between synchronous speed speed of rotation of magnetic field and rotor speed speed of rotatory part of induction motor. Slip of an induction motor is negative when a magnetic field and rotor rotate in opposite direction. Download 3 phase induction motor powerpoint presentation. To start induction motor by rotor resistance starter 8. Fault identification of 3phase slip ring induction motor free download as powerpoint presentation.
The value of slip in induction motor is can never be zero. Record all nameplate information for the induction motor. Fall 2005 ee595s electric drive systems 2 overview of strategies voltsperhertz control constant slip control fieldoriented control. In these types of motors the start winding can have a series capacitor andor a. Learn more about the construction and operation of a slip ring induction motor. You should also make a dc measurement of stator winding linetoline resistance using a dmm. S nsnrnsx100% ns synch speed nr rotor speed sslip slip increase with increase of mechanical load.
Generally, it is known as the asynchronous motor because its running speed is less than its synchronous speed. In this article, i will discuss which motor is best to use, the squirrel cage motor is best or slip ring induction motor is best. Ppt induction motor powerpoint presentation free to. When a three phase induction motor connected to a single phase power supply using the. Fall 2005 ee595s electric drive systems 36 the plan continued achieving 14. The construction of stator of the induction motor is almost the same as other motors.
When a motor starts to rotate the slip is 100 % and the motor current is at maximum. The value of slip in induction motor at full load varies from about 6% for small motors to about 2% for large motors. Almost 80% of the mechanical power used by industries is provided by three phase induction motors because of its simple and rugged construction, low cost, good operating characteristics, the absence of commutator and good speed regulation. The stator is the outer component of the motor which can be seen. I will also discuss the advantages and disadvantages of squirrel cage and slip ring induction motor, and conclusion. Singlephase induction motor threephase induction motor singlephase induction motor there are probably more singlephase ac induction motors in use today than the total of all the other types put together. Slip s can be defined as the difference between the flux speed ns and the rotor speed n. The tendency of the rotor teeth to remain under the stator teeth due to direct magnetic attraction is reduced. Construction of three phase induction motor electrical4u. There are two types of induction motors, one with wound type rotor, also called slip ring motor and another one with squirrelcage rotor. It is logical that the least expensive, lowest maintenance type. Squirrel cage rotor wound type rotor or slip ring type rotor squirrel cage rotor in this type. The speed of an ac motor depends on the frequency of the input power and the number of poles for which the motor is wound.
The 3phase set of currents, each of equal magnitude and with a phase. Slip ring induction motor is made up from wound rotor and squirrel cage induction motor is made up from the squirrel cage rotor. Menzel 3phase slip ring induction motors in protection class ip 55 are designed in the ic 411 cooling class. To understand the torque slip characteristics of induction motor we should focus on mathematics relations. For your splitphase motor lab, you may assume the free running current and power represent the zeroslip. If the slip is zero, what is the speed of a induction motor. The most commonly used is the squirrel cage induction motor. In this video, i will explain you about the working of the threephase induction motor. Stator winding can be either star or delta connected depending upon the design. Optimal volume and slip of a three phase induction motor using differential evolution. Rotor as the name suggests it is a rotating part of an electrical machine, in which current is induced by transformer action from rotating magnetic field. Electric energy and induction motors the level of prosperity of a community is related to its capability to produce goods and services.
As previously, we have covered a lot of important topics. A 4 pole, 3 phase induction motor is supplied from hz supply. Malagoli and others published optimal volume and slip of a three phase induction motor using differential. The maximum torque that the motor can develop typically 2. If the emf in the rotor of an 8 poles induction motor has a frequency of 1. There are two types of induction motors, one with wound type rotor, also called slipring motor and another one with squirrelcage rotor. L r s and be the angular velocities of the magnetic field line frequency, rotor, and slip respectively. What happens in the value of a slip from noload to a full. An induction motor can therefore be made without electrical connections to the rotor. A variable frequency ac induction motor servo control system wherein slip is generated as a function of stator current. Induction motor equations engn1931f spring 2017 5 for low slip frequencies, the power of the motor is simply proportional to the product of the square of the gap field strength with the volume of the rotor and the noload speed of rotation. Slip in electrical induction motors engineering toolbox.
Threephase induction motors are the most common and. Introduction to induction motor the engineering projects. The rotor and stator are separated by an air gap which allows free rotation of the rotor. Motor runs smoothly as the magnetic hum is reduced b. Slips can be defined as the difference between the flux speed ns and the rotor speed n. Rotor induction motor an overview sciencedirect topics. In fact, an induction motor can be treated as a rotating transformer i. Free download induction motor seminar ppt, pdf report. A stator is in all the motor only winding on the stator is vary with types of motor. The generally humidityprotected motor winding is designed to be in thermal class f and is impregnated using the vpi process. Previously we shared the book on ac motors which explains all these properties briefly, this post is focused on the induction motor formulas and calculation examples. Nov 27, 2019 the three phase induction motor is the most widely used electrical motor. The performance calculation by means of finding torque, slip and efficiency. What are four possible causes if the brushes for a slip.
How an induction motor works by equations and physics. The motor is mounted in a test rig that allows one to control the torque applied to the motor shaft and to measure both rpm and torque. Electrical motor free download as powerpoint presentation. In a preferred embodiment the slip per ampere ratio is constant in the range from zero to approximately base speed and thereafter increases exponentially as. Squirrel cage rotor wound type rotor or slip ring type rotor squirrel cage rotor in this type rotor as the name suggests it is a rotating part of an electrical machine, in which current is induced by transformer action from rotating magnetic field. The slip of the induction motor varies from 5 percent for small motors to 2 percent for large motors. It is logical that the least expensive, lowest maintenance type motor should be used most often. The rotor will constantly be turning to align its magnetic field with that of the stator field. Such properties include a number of poles, speed, frequency, slip, starting current and rated horsepower. That is why such motors are known as induction motors. Introduction types of electrical machines types of 3ph induction motor basic principle working principle compnents of induction motor application comparision between 1ph i. Fault identification of 3phase slip ring induction motor. The stator works as the primary while the rotor works as the secondary.
When a three phase induction motor connected to a single phase power supply using the steinmetz connection operates in a practical noload condition, not all windings consume active power. Torque slip characteristics of induction motor full guide. It seems very odd that you want exactly four answers. Electrical interview questions which motor is best.
If an induction motor with certain ratio of rotor to stator slots, runs at 17 of the normal speed, the phenomenon will be termed as a humming b hunting c crawling d cogging ans. The difference multiplied with hundred and divisible by the synchronous speed is called the slip percentage. Jan 11, 2018 such properties include a number of poles, speed, frequency, slip, starting current and rated horsepower. Protection of induction motor free download as powerpoint presentation. Speed control of induction motor detailed explanation. Now, if the conducting ladder is free to move now you are allowing to move. Higher protection classes can be realized on request at any time. Slip of induction motor electrical engineering interview. An induction motor or asynchronous motor 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. Therefore, the rotor thus cannot reach the synchronous speed ns it will slip. Fullload slip varies from less than 1 % in high hp motors to more than 56 % in minor hp motors. The stator of slip ring induction motor is very much the same as that of the squirrel cage induction motor, but the construction of its rotor is very much different.
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