Record all nameplate information for the induction motor. The ac induction motor is the most used electrical motor in industrial applications worldwide. An ac motor may be part of a pump or fan, or connected to some other form of mechanical equipment such as a winder, conveyor, or mixer. The 3phase set of currents, each of equal magnitude and with a phase difference of 120o, flow in the stator windings and generate a rotating field will constant magnitude. 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. Generally, it is known as the asynchronous motor because its running speed is less than its synchronous speed. The advantages of threephase ac induction motor are listed below. Alternating flux is produced around the stator winding due to ac supply. The basic principles of the operation of a three phase inverter is explained, following which the. What is autotransformer starter,working principle,diagram. According to this law, an emf induced in a conductor due to the rate of change of flux linkage through the conductor. Principles of operation of synchronous machines the synchronous electrical generator also called alternator belongs to the family of electric rotating machines.
In an induction motor, the electric current in the rotor needed to. Hence another starting method is used to start three phase induction motor called an autotransformer starter. Ss 120 x f p 120 x 60 8 900 rpm rotor speed motor slip is known, equation 2. An induction motor also known as an asynchronous motor is a commonly used ac electric motor. As mentioned above that, due to the rotating magnetic field of the stator, the induction motor becomes self starting.
Starting of 3phase induction motors the induction motor is fundamentally a transformer in which the stator is the primary and the rotor is shortcircuited secondary. Induction motor working principle single phase and three. Auto transformer starter can be used for both stardelta connected. The 3phase set of currents, each of equal magnitude and with a phase difference of 120o, flow in the stator windings and generate a rotating. Due to this flux rotor current induced and rotor flux also generated. Single phase machines are restricted to small power levels. It is made up of a number of stampings, which are slotted to receive the windings fig. 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. In fact, an induction motor can be treated as a rotating transformer i. Other members of the family are the directcurrent dc motor or generator, the induction motor or. Construction an induction motor has two main parts.
A slip ring, three phase induction motor rotates at a speed of 1440rpm. The main methods employed for speed control of induction motors are as follows. An electrical motor is an electromechanical device that converts electrical energy into mechanical energy. Basic working principle of an induction motor alternating flux is produced around the stator winding due to ac supply. The induction motor consists of a two magnetically connected systems namely, stator and rotor. Improves the starting torque of single phase motors and incorporates a simple brake. Working principle of an induction motor circuit globe. Principle of operation of single phase induction motor. T s t 2 3 2 3 sa b sc e i a i b in principle thedtc method selects one of the six nonzero and two zero voltage vectors of the inverter on the basis of the instantaneous errors in torque and stator flux magnitude.
Induction motors objective the aim of this chapter is to gather knowledge about the following topics of induction motors. The last one is very important because a generator is a reverse motor. Free download induction motor seminar ppt, pdf report. Also, the induction motor operates on the same principle as the transformer. Siemens manufactures a wide variety of motors for various applications. Bldc motors do not experience the slip that is normally seen in induction motors. Construction, types and principle of operation of 3phase induction motors.
This means the magnetic field generated by the stator and the magnetic field generated by the rotor rotate at the same frequency. The performance calculation by means of finding torque, slip and efficiency. A single phase induction motor is inherently not selfstaring can be shown easily. This tutorial will introduce the user to the fundamental electrical and mechanical principles of ac electric induction motor design and application. Learn the principle of power factor improvement and evaluating the cost of electricity. 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.
As the rotor winding in an induction motor are either closed through an external resistance or directly shorted by end ring, and cut the stator rotating magnetic field, an emf is induced in the rotor copper bar and due to this emf a current flows through the rotor conductor. Click on the following steps in sequence to get a graphical picture. The electromagnetic induction is the phenomenon in which the electromotive force induces across the electrical conductor when it is placed in a rotating magnetic field. Depending on rotor construction, induction motors are classified as.
Rg,rset based on type of ac supply, three phase induction motors. The motor which works on the principle of electromagnetic induction is known as the induction motor. The principle of operation of three phase induction motors is based on the production of rotating magnetic field. An induction motor consists essentially of two main parts. Like any electric motor, a 3phase induction motor has a stator and a rotor. The motor works on the principle of faradays law of electromagnetic induction. At starting, the voltage induced in the induction motor rotor is maximum q s 1. The rotating magnetic field produced in the stator will create flux in the rotor, hence causing the rotor to rotate. Speed control of induction motors the speed of an induction motor is given as n 120fp 1s.
The analysis of the single phase motor can be made on the basis of two theories. Specific emphasis will be given to pump applications. Introduction types of electrical machines types of 3ph induction motor basic principle working principle compnents of induction motor application comparision between 1ph i. The difference between a transformer and im is the transformer is a static device whereas the im is a rotating device. You should also make a dc measurement of stator winding linetoline resistance using a dmm. For understanding the working principle of an induction motor, let us consider a simple setup first as shown in the figure. Virtually all electrical motors use magnetic field rotation to spin their rotors. An induction motor im is a type of asynchronous ac motor where power is supplied to. Pdf basic soft starter principles the principles of.
Induction motor works on the principle of electromagnetic induction. Due to its simplicity of construction, low cost, reliability and relatively high efficiency, it is likely to remain the prime source of mechanical energy for industrial applications. Since the rotor impedance is low, the rotor current is excessively large. The basic idea of an electric motor is to generate two magnetic fields. The material presented in this course will help in selection of a motor for a specific application. The steady state equations for the induction motor are obtained. And yet, developed torque of the induction motor is obtained using the developed mechanical power expression. That is why such motors are known as induction motors. Thus second flux is produced according to the induction principle due to induced e. Motors transform electrical energy into mechanical energy. Apr 16, 2020 working principle of threephase induction motor. Nov 15, 2020 synchronous speed is the speed of rotation of the magnetic field in a rotary machine, and it depends upon the frequency and number poles of the machine. Sep 04, 2019 we shall study in detail about this type in this article like what is an induction motor, working principle, types, advantages, and applications.
Constructed by laminated silicon steel plates by stamping for the purpose of reducing the eddy current losses and hysteresis losses. When threephase stator winding of an induction motor is energized from a 3 phase supply, a rotating magnetic field is set up which rotates around the stator at synchronous speed n s. The synchronous speed of the motor is given by equation 1. Operating principle like most motors, an ac induction motor has a fixed outer portion, called the stator and a rotor that spins inside with a carefully engineered air gap between the two. In squirrel cage induction motor, the rotor bars are shortcircuited by end rings and in slipring induction motor, the rotor winding is connected with external resistors.
C supply to stator winding flux generated in the stator winding. Other motors that are included are 1phase induction motors, permanent synchronous motors and synchronous reluctance motors. In a dc motor, supply is needed to be given for the stator winding as well as the rotor winding. For example, in a credit cards the magnetic strips on the back of the card or in order to generate voltage in motors. Before discussing the theory of operation for the induction motor a. When three phase supply is given to the stator winding, a rotating magnetic field of constant magnetic field is produced. Principle of operation of the dc induction motor sage journals. An ac motor of this type may be part of a pump or fan or connected to some other form of mechanical equipment such as a winder, conveyor, or mixer. An induction motor can therefore be made without electrical connections to the rotor. The rotor has salient poles and a cage so that it starts like an induction motor, and runs like a synchronous motor. Although single phase induction motor is more simple in construction and is cheaper than a 3phase induction motor of the same frame size, it is less efficient and it operates at lower power factor. Induction motor reversible motor electromagnetic brake motor a motor that can operate continuously in a certain direction.
Pdf basic soft starter principles the principles of fixed. Induction motors and transformers both im and transformer works on the principle of induced voltage transformer. Construction and operating principle bldc motors are a type of synchronous motor. Squirrel cage induction motor started on full line voltage using d o l starter as a starting method draw very large starting current which can damage motor winding and also create a current surge on the power system. 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. In the case of threephase ac alternating current operation, the most widely used motor is a 3 phase induction motor, as this type of motor does not require an additional starting device. Pdf in this research, we start from the construction of the induction motor and its main parts function. Ac motors are used worldwide in many applications to transform electrical energy into mechanical energy. Ac motors are used worldwide in many residential, commercial, industrial, and utility applications. Starting of 3 phase induction motors, high starting. The rotor is separated from the stator by a small airgap which ranges from 0.
The stator carries a 3phase winding called stator winding while the rotor carries a. It is similar to a transformer which also works on the same principle. Basics of induction the phenomenon of the electromagnetic induction is therefore based on three physical principles, here below explained. An induction motors rotor can be either wound type or squirrelcage type. Single phase induction motor, theory of operation double. But in an induction motor only the stator winding is fed with an ac supply. Ac motors are found on a variety of applications from those that require a single motor to applications requiring several motors. An electric motor is an electromechanical device that used to convert electrical energy into mechanical energy. Generally, induction motors are categorized based on the number of stator windings.
This is similar to a transformer that also has two magnetically connected systems namely primary and secondary windings. Torque versus slip speed of an induction motor with constant stator flux both open and closedloopcontrol of the speed of an ac induction motor can be implemented based on. The relative speed between the rotating flux and static rotor conductor is the cause of current generation. An ac motor of this type may be part of a pump or fan or. The induction motor always runs at speed less than its synchronous speed. Other members of the family are the directcurrent dc motor or generator, the induction motor or generator, and a number of derivatives of all these three. Dec 19, 2015 single phase induction motors are used primarily for domestic and lightindustrial applications where threephase supply is generally not available. Jan 28, 2020 here we will discuss the induction motor s construction and working in detail. A 3 phase induction motor has two main parts i stator and ii rotor. Uses soft magnet rotor that is magnetized by the application of current in the stator coils 3. T s t 2 3 2 3 sa b sc e i a i b in principle thedtc method selects one of the six nonzero and two zero voltage vectors of the inverter on the basis of the. 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. Ac motors are electric motors that rotate by using. Basic soft starter principles the principles of fixedspeed induction motor control since its invention one hundred years ago, the standard 3phase induction motor has become one of the most familiar items of industrial equipment ever known.
The speed of rotating magnetic field is synchronous speed, n s r. There are many types of ac motors, but this course focuses on threephase induction motors, the most common type of motor used in industrial applications. As the rotor winding in an induction motor are either closed through an external resistance or directly shorted by end ring, and cut the stator. Jan 08, 2019 we saw the working principle of squirrel cage induction motor which is the same in all induction motor. Working principle of threephase induction motor electrical. The rotor will constantly be turning to align its magnetic field with that of the stator field. Here, two iron or ferrite cores of equal sizes are taken and are suspended in the air at a distance. Induction motor seminar ppt, pdf report study mafia. A slip ring, three phase induction motor rotates at a speed of 1440rpm, when a supply of 400v, 50hz is.
8 1172 1808 815 629 532 778 441 33 1178 401 599 1678 1624 1736 872 683 621 1244 1535 1065 1194