Module 8 threephase induction motor version 2 ee iit, kharagpur lesson 30 construction and principle of operation of im version 2 ee iit, kharagpur in the previous, i. Starting of 3 phase induction motors, high starting torque motors, speed control, rheostatic method, pole changing method cascade control of speed, double cage induction motor, cogging and crawling of induction motor, induction generator. The rotor will constantly be turning to align its magnetic field with that of the stator field. In an induction motor, the rotor rotates because of slip i. Find the percentage slip and number of poles of the induction motor. Before starting to explain how an induction asynchronous generator works, i assume that you know the working principle of an induction motor.
Induction machines 1 introduction the induction machine was invented by nikola tesla in 1888. The main difference in a slip ring induction motor is on the rotor construction and usage. Some changes in the stator may be encountered when a slip ring motor is used in a cascaded system, as the supply for the slave motor is controlled by the supply from the rotor of the other slip ring motor with external resistance mounted on its rotor. An induction motor is practically a constant speed motor, that means, for the entire loading range, change in speed of the motor is quite small. An induction motor always operates at a speed lower than the synchronous speed because the rotating magnetic field that occurs in the stator will generate flux in the rotor that will cause the rotor to rotate, but due to the delay of the flow current in the rotor with current flow in the stator, the rotor will never reach its rotating magnetic field speed, that is, the synchronous. Circle diagram of an induction motor its construction. Note down the machine ratings and calculate rated current of the machine noload test. Power from electric motor to driven is delivered by transmitting device. Understand the principle and the nature of single phase and 3 phase induction machines. Nptel electrical engineering electrical machines ii. Vf speed control of 3 phase induction motor using space. Induction motor basics, single phase and three phase. 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. It is logical that the least expensive, lowest maintenance type motor should be used most often.
Advantages of 3 phase induction motor generally easy to build and cheaper than corresponding dc or synchronous motors induction motor is robust. Induction motor totallyenclosed fancooled nema standard epact three phase induction motors sdesign versatility teco totally enclosed fan cooled squirrelcage induction motors are designed, manufactured and tested to meet or exceed the latest nema, ieee, csa and. The slip power can either be returned to the supply or added to the motor shaft output. Just like a dc machine, a same induction machine can be used as an induction motor as well as an induction generator, without any internal modifications. The stator or the stationary part consists of three phase winding held in place in the slots of a laminated steel core which is enclosed and supported by a. Ac induction motors are also the most common motors used in main powered home appliances. The induction motor plays very important role in industrial sectors, primarily due to its robustness and low cost. View notes l29nkdet eenptel from eso 203 at iit kanpur. Introduction types of electrical machines types of 3ph induction motor basic principle working principle compnents of induction motor application comparision between 1ph i. Synchronous motor drives are close competitors to induction mo tor drives in many industrial applications. The basic idea of an electric motor is to generate two magnetic fields. Circuit diagram for noload and blockedrotor test on 3 phase induction motor a.
Slip ring motor fundamentals bright hub engineering. Simplified steadystateequivalent circuit of induction motor. Moduleiv 10 hours single phase induction motor, theory of operation double revolving field theory, equivalent circuit, determination of parameters methods of starting, split phase starting, repulsion starting, shaded pole starting, performance characteristics. Nptel provides elearning through online web and video courses various streams. Equivalent circuit of an induction motor enables the performance characteristics which are evaluated for steady state conditions.
However, recently, it has been increasingly used as variable speed motors driven by an inverter. There are two basic reasons for the use of singlephase motors rather than 3phase motors. The threephase induction motor is the extensively used for various kinds of industrial drives. Induction motor works on the principle of induction where electromagnetic field is induced into the rotor when rotating magnetic field of stator cuts the. As a voltage and a current is applied to the stator winding terminals. It is a maintenancefree, less noisy and efficient motor. The construction of the circle diagram is based on the approximate equivalent circuit shown below. For reason of economy, most houses, offices and also rural areas are supplied with single phase a. Induction generators are also called as asynchronous generators. You should also make a dc measurement of stator winding linetoline resistance using a dmm. Noload and blocked rotor test on an induction machine aim.
Nptel syllabus advanced electric drives video course course outline. Lecture series on industrial automation and control by prof. This paper presents design and analysis of a three phase induction motor drive using igbt. Introduction to induction motor instrumentation and. But it is negative for supersynchronous, speed slip frequency adjustable voltages are inserted in the rotor circuit for induction motor speed control. Chapter 3 induction motor and different speed control methods page no 3. Gradually apply three phase voltage across motor stator terminals via the autotransformer d. Differentiate between the various types of generating electric power stations. An induction motor also known as an asynchronous motor is a commonly used ac electric motor.
May 04, 2020 ppt threephase induction motor electrical engineering ee notes edurev is made by best teachers of electrical engineering ee. It is available from fractional horsepower ratings to megawatt levels. Right from its inception its ease of manufacture and its robustness have made it a very strong candidate for electromechanical energy conversion. Introduction to induction motor instrumentation and control. A 480v, 60 hz, 6pole, threephase, deltaconnected induction motor has the following parameters. The most popular type is the 3phase, squirrelcage ac induction motor. Slip power recovery system in three phase slip ring. Induction motor drives with closedloop control are used in similar applications to d. May 18, 2008 lecture series on industrial automation and control by prof. May 31, 2019 a linear induction motor or lim is a special type of induction motor used to achieve rectilinear motion rather than rotational motion as in the case of conventional motors.
List and describe the more commonly used equipment in an electric substation. In this project paper microcontroller based system to control speed of induction motor is developed using pulse width modulation technique 2. Module 8 threephase induction motor version 2 ee iit, kharagpur lesson 29 rotating magnetic field in. Then, equation 1 can be shown in terms of magnitude as. Speed torque characteristics of induction motor from eq. Noload and blocked rotor test on an induction machine aim theory. It is a 16 bit highperformance digital signal controller dsc. The 3phase set of currents, each of equal magnitude and with a phase. Ppt threephase induction motor electrical engineering.
Induction motors have been traditionally used as constant speed motors supplied by the ac power source. If the induction motor is operating in the linear magnetic region, the lm is constant. Noload and blocked rotor test on an induction machine. Mostafa elshahed objectives learn a brief history of the electrical power systems construction. Squirrel cage wound rotor with slip rings the rotating magnetic field the basic idea of an electric motor is to generate two magnetic fields. The induction motor stator resembles the stator of a revolving field, three phase alternator. Perform an analysis on induction machines which is the most rugged and the most. Induction motor theory jerry bednarczyk, pe course content introduction the ac induction motor is well suited to applications requiring constant speed operation. It supplies an induction motor ich has a full load speed of 144wh 0 rpm. Linear induction motors are quite an engineering marvel, to convert a general motor for a special purpose with more or less similar working principle, thus enhancing its.
Disconnect any mechanical load connected to the induction motor. The induction motor is made up of the stator, or stationary windings, and the rotor. It is the diagrammatic representation of the performance of the induction motor. The bars forming the conductors along the rotor axis are connected by a thick metal ring at the ends, resulting in a short circuit as shown in figure 1. In general, the induction motor is cheaper and easier to maintain compared to other alternatives. This document is highly rated by electrical engineering ee students and has been viewed 2535 times. Starting of 3 phase induction motors, high starting torque motors, speed control, rheostatic method, pole changing method, cascade control of speed, double cage induction motor, cogging an d crawling of induction motor, induction generator. Fall 2005 ee595s electric drive systems 3 voltsperhertz control history. The stator or the stationary part consists of three phase winding held in place in the slots of a laminated steel core which is enclosed and supported by a cast iron or a steel frame as shown in fig.
Nov 03, 2019 an induction motor also known as an asynchronous motor is a commonly used ac electric motor. Speed control of induction motor using pwm technique. A wound rotor, has a 3phase winding similar to the stator winding. A stator winding is placed in the stator of induction motor and the three phase supply is given to it. A motor with only armortisseur windings is called an induction motor.
When the mechanical load is applied to induction motor which requires speed. 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. When the rotor resistance is increased, so is the slip for maximum torque, and the stable operating slip range of the. Circle diagram of an induction motor the circle diagram of an induction motor is very useful to study its performance under all operating conditions. Fall 2005 ee595s electric drive systems 2 overview of strategies voltsperhertz control. A three phase, 12 pole, salient pole alternator is coupled to a diesel engine running at 500 rpm.
An induction motor is based on the principle of induction of voltages and currents. Induction motor 1 chapter 3 induction motor bee23 electrical machine power system 2 learning outcomes. They are generally more expensive than induction motor dri ves,but the advantages is that the efficiency is higher,which is tends to lower the life cycle cost. Methods of starting three phase induction motors as we know, once a supply is connected to a three phase induction motor a rotating magnetic field will be set up in the stator, this will link and cut the rotor bars which in turn will induce rotor currents and create a rotor field which will interact with the stator field and produce rotation. The voltage and current is induced in the rotor circuit from the stator circuit for the operation. Slip power recovery system in three phase slip ring induction. The rotor terminals are connected to three slip rings which turn with the. The sinusoidal stator phase currents fed in the stator coils create a magnetic field. Single phase induction motor the singlephase induction machine is the most frequently used motor for refrigerators, washing machines, clocks, drills, compressors, pumps, and so forth. The stator is supplied by a balanced 3phase ac power source. The stator consists of a series of wire windings of very low resistance permanently attached to the motor frame. Mutilevel converterfed induction motor drive utility friendly induction motor drive 02 03 03 02 01 01 4 control of synchronous motor self controlled synchronous motor vector control of synchronous motor 02 02 nptel. The slip power for an induction motor is positive for subsynchronous speed because slip is positive. As its name indicates stator is a stationary part of induction motor.
An induction motor is the most modest electrical machine from constructional point of view, in the majority of the cases. Fall 2005 ee595s electric drive systems 2 overview of strategies voltsperhertz control constant slip control fieldoriented control. Record all nameplate information for the induction motor. The rotor of an induction motor can be a squirrel cage rotor or wound. Pdf speed control of induction motor using pi and vf. In an induction motor, the electric current in the rotor needed to produce torque is obtained via electromagnetic induction from the rotating magnetic field of the stator winding. An induction motor always operates at a speed lower than the synchronous speed because the rotating magnetic field that occurs in the stator will generate flux in the rotor that will cause the rotor to rotate, but due to the delay of the flow current in the rotor with current flow in the stator, the rotor will never reach its rotating magnetic field speed, that is, the synchronous speed. Speed of a dc shunt motor can be varied very easily with good efficiency, but in case of induction motors, speed reduction is accompanied by a corresponding loss of efficiency and poor power factor. At the end of the lecture, student should be able to.
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