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. Electric drives ac motors description and applications ac motors. Characteristically, linear induction motors have a finite primary or secondary length, which generates endeffects, whereas a conventional induction motor is arranged. Woundrotor motors can be started with low inrush current, by inserting high resistance into the rotor circuit. When the machine is fed by an inverter a series of issues that can. A linear induction motor lim is an alternating current ac, asynchronous linear motor that works by the same general principles as other induction motors but is typically designed to directly produce motion in a straight line.
Induction motor testing and evaluation summary as energy costs rise, more emphasis is being placed on determining the health of large inductive motors. Induction motor definition of induction motor by merriam. The first industrial motors of this type were constructed at the end of the nineteenth century and soon gained the favor of users who appreciated their raggedness, simplicity and relatively low manufacturing cost compared to dc commutator motors. In twopole singlephase motors, the torque goes to zero at 100% slip zero speed, so these require alterations to the stator such as shadedpoles to provide starting torque. Combining the wave drive and the fullstep drive leads to in total eight possible.
The 3phase induction motor is used in the larger horsepower application above 1 hp while the singlephase ac motors were used in the. A linear induction motor consists of a laminated coil assembly and an aluminum and steel reaction plate. When selecting a 3phase induction motor for an application several motor types can fill the need manufactures often specify the motor class best suited to drive the load 3phase induction motors under 500 hp are standardized the frames have standard dimensions a 25 hp, 1725 rpm, 60 hz motor from one manufacture can be. Therefore, these motors are frequently used in industry. The most common type of ac motor being used throughout the work today is the induction. We know from our experience and knowledge that, among the induction motors, the squirrel cagetypes are the most simple of all electric motors. This is done by using alternating currents to create a rotating magnetic field. Nov 03, 2019 an induction motor also known as an asynchronous motor is a commonly used ac electric motor. Therefore a new term is needed to describe the induction motor. There are two general types of ac motors used in aircraft systems. Based on the rotor construction, 3 phase induction motor can be of two types. Threephase induction motors are the most common and frequently encountered machines in industry simple design, rugged, lowprice, easy maintenance wide range of power ratings. Therefore such motors are known as induction motors.
Two main types of induction motoran induction motor also known as an asynchronous motor or squirrelcage motor is atype of an ac alternating current motor. The single phase motors may be of the following types. Lecture 6 three phase induction motors cairo university. Adjusting the resistance allows control of the speedtorque characteristic of the motor. We know from our experience and knowledge that, among the induction motors, the squirrel cage types are the most simple of all electric motors. Squirrel cage induction motors suffer from several faults such as rotor broken bar. An induction motor can be treated as a rotating transformer i. It has been more than a century since the principle of the operation of induction motors was discovered. An ac motor of this type may be part of a pump or fan or. These motors are selfstarting and use no capacitor, start winding, centrifugal switch or other starting device. Design of highspeed induction motors linear induction motors. Comparison between direct and indirect field oriented control.
In phase wounded rotor always double layer, distributed windings are used in alternators even the stator has two phases. These are of two types, squirrel cage and slip ring motors. Squirrel cage motors wound rotor motors 3phase synchronous motors are most commonly used in. May 22, 2017 types induction motor single phase induction motor 1. The three phase induction motors are simple in construction, rugged, low cost and easy to maintain. They are greater than one horse power or one kilowatt. The amount of thrust produced by the lim is proportional to the active surface area of the motor. A three phase supply is given to the stator of the induction motor. Teco totally enclosed fan cooled squirrelcage induction motors are designed, manufactured and tested to meet or exceed the latest nema, ieee, csa and other international standards. As a result, motor manufactures have tried, over the last few decades, to perfect various types of a. Difference between induction motor and synchronous motor. Pdf an investigation of induction motor saturation under.
Types, losses in induction motors, motor efficiency, factors affecting motor performance, rewinding and motor replacement issues, energy saving opportunities with energy efficient motors. An induction motor also known as an asynchronous motor is a commonly used ac electric motor. These motors are suitable for all general applications where an open machine is not applicable due to severe environments such as excessive dirt, dust andor moisture. Ge began developing 3phase ac induction motors beginning in 1891 under charles steinmetzs leadership. One of the powerful methods to detect induction motor faults is the line current signature analysis. Applications of induction motor polyphase wound rotor. The basic idea of an electric motor is to generate two magnetic fields.
It has the stator of an induction motor, and the rotor of a dc motor. So called because rotor tries to line up with the rotating magnetic field in the stator. What is common to all the members of this family is that the basic physical process involved in their operation is the conversion of electromagnetic energy. A single phase induction motor requires separate starting circuitry to provide a rotating field to. Depending upon the application requirements, a particular motor can be selected. Induction motor theory jerry bednarczyk, pe course content introduction the ac induction motor is well suited to applications requiring constant speed operation. In an induction motor, power is supplied tothe rotor via an electromagnetic induction. Pdf construction of three phase linear induction motor. Typical nema design b induction motor speedtorque curve.
The ac induction motor is a common form of asynchronous motor whose operation depends on three electromagnetic phenomena. The induction motor is so named because no external voltage is applied to its rotor. High grade silicon steel laminations that build up the core are precision punched from coreplated sheets. Induction motor starting can be analyzed using electrical, mechanical, and thermal models which interact as diagrammed in figure 1. There are two types of induction motors, one is named as single phase induction motor, while the second one is named as 3 phase induction motor. There are a variety of motor types available in the market, including induction motors, servomotors, dc motors brushed and brushless, etc. Shaded pole induction motor three phase induction motor 1.
Applications of induction motor the polyphase induction motor is a motor whose stator contains a number of windings. Pdf in general induction machines are designed for sinusoidal voltages supply. Induction motor definition is an alternatingcurrent motor in which torque is produced by the reaction between a varying magnetic field generated in the stator and the current induced in the coils of the rotor. Threephase induction motors are also called asynchronous motors. The advantages of threephase ac induction motor are listed below. Threephase ac induction motors are widely used in industrial and commercial applications. Model number m800006 outline dimension drawing see figure 4 nameplate data 1 see figure 5 rated frequency 50 hz motor location indoor altitude less than meters relative humidity less than 90% ambient temp 40 degrees c max duty type continuous weight approx. Types induction motor single phase induction motor 1. Stator as the name indicates stator is a stationary part of induction motor. 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. When the windings in the stator are energized it induces current in the windings in the rotor this invisible force is call induction, learn about the concept of induction here.
However, a current trend is that most new designs are moving towards brushless dc motors, popularly known as bldc motors. An induction or asynchronous motor is an ac electric motor in which the electric current in the rotor needit tae produce torque is obtained bi electromagnetic induction frae the magnetic field o the stator windin. There are three basic types of small induction motors. An induction motor or asynchronous motor is an ac electric motor in which the electric current.
Three phase induction motors are used where large amounts of power are required. The rotor of an induction motor can be a squirrel cage rotor or wound. Splitphase motors i resistancestart motor ii capacitorstart motor iii permanentsplit singlevalue capacitor motor iv twovalue capacitor motor. Combining an inservice motor with a vfd provides facil ities with an effective speed. You should also make a dc measurement of stator winding linetoline resistance. Characteristics of a three phase and single phase induction motor. Either type may be single phase, two phase, or three phase. To produce larger forces, multiple coil assemblies can. Squirrel cage and wound rotor or slip rig induction motor. What is common to all the members of this family is that the basic physical process involved in their operation is the conversion of electromagnetic energy to mechanical energy, and vice versa.
Dec 11, 20 induction motors induce a current into an electromagnetic rotor in order to create rotation. Induction motor is an ac electric motor, having a stator and a rotor just like other motors, but the working principle is a little different which would be discussed further. Combining its lengthy experience in the use of new techniques with the industrial might. Squirrel cage wound rotor with slip rings the rotating magnetic field. However, all types of the machines in this handbook can also be operated as. Rotor has winding, same as stator and the end of each phase is connected to a slip ring. Besides the enclosure, performance of the induction motors is the same as that of the other motors, as per the particular design. Induction motors are optimal for unidirectional and continuous operation such as a. One singlephase wattmeter plus miscellaneous apparatus as needed. Difference between induction motor and synchronous motor difference between induction and synchronous motor is explained with the help of various factors, like the type of excitation used for the machine.
Like any other electrical motor, induction motors have two main parts the rotor and the stator. Mostafa elshahed objectives learn a brief history of the electrical power systems construction. Ac induction motors are the most common motors used in industrial motion control systems, as well as in main powered home appliances. The induction motor has two sets of windings copper or aluminum wire coiled to form electromagnets. They operate such devices as starters, flaps, landing gears, and hydraulic pumps. Eee page 5 it is usually for large 3 phase induction motors. Ultrahigh frequency effects of power electronics tests on induction machines.
Various types of ac induction motors are available in the market. Differentiate between the various types of generating electric power stations. An induction motors rotor can be either wound type or squirrel cage type. Electric drives ac motors description and applications. There are single phase induction motors and three phase induction motors.
An induction motor is also called asynchronous motor as it runs at a speed other than the synchronous speed. This magnetic field opposes the revolving magnetic field and will combine with the. The induction motor is made up of the stator, or stationary windings, and the rotor. Induction motors continued to evolve in form and use. Torque and speed characteristics of various types of motors. In an induction motor, the electric current in the rotor needed to produce torque is obtained via electromagnetic induction. Simple and rugged design, lowcost, low maintenance and direct connection to an ac power source are the main advantages of ac induction motors. These two factors combine to give the higher speciwc torque. Induction motors induce a current into an electromagnetic rotor in order to create rotation. Basic design and theory of operation the alternating current ac induction motor is one of the most rugged and most widely used machines in.
In the electrical model, the voltage, v, and the slip, s, determine the rotor current. Development of the induction motor equivalent circuit. Single phase induction motors arenot a selfstarting motor, and three phase induction motor are a selfstarting motor. Introduction to induction motor the engineering projects. In general, the induction motor is cheaper and easier to maintain compared to other alternatives. The types of induction motor depend upon the input supply. As the name indicates stator is a stationary part of induction motor. One third of the worlds electricity consumption is used for running induction motors driving pumps, fans, compressors, elevators and machinery of various types. Section 5 threephase induction motors by hashem oraee pdf. The singlephase stator winding produces a magnetic field that.
Pdf in this research, a new easy and fast correlations derived from. The summation of all torques acting on the motor shaft comprises the mechanical model. Pdf a comparison of a three phase induction motor fed by two. In tefc motors, interior losses are dissipatit indirectly throu enclosur fins maistly bi forced air convection. Sep 27, 2016 induction motor is an ac electric motor, having a stator and a rotor just like other motors, but the working principle is a little different which would be discussed further. Synchronous and asynchronous ac inductionasynchronous motor an induction or asynchronous motor is an ac electric motor in which the electric current in the rotor needed to produce torque is induced by electromagnetic induction from the magnetic field of the stator winding. A woundrotor motor, also known as slip ringrotor motor, is a type of induction motor where the rotor windings are connected through slip rings to external resistance. Induction motors horizontal and vertical stator stator construction the stator is composed of a supporting structure, a core of electrical laminations and insulated windings. They run at a constant speed from noload to the full load. Ac motors are used worldwide in many applications to transform electrical energy into mechanical energy.
The fundamental laws associated with the relationship between electricity and magnetism were derived from experiments conducted by several key scientists in the 1800s. Following data is taken from no load, locked rotor, and dc tests of a 3phase, wye connected 40 hp, 60 hz, 460 v, induction motor with a. Comparison between direct and indirect field oriented. Induction motors are made in both threephase and singlephase types.
Motor current monitoring and analysis mcsa is a straight forward tool to diagnosing problems with large inductive motors. Improving motor and drive system performance department of. The speed of the motor, starting and operation, the efficiency of both the motors, its cost, usage, and applications. Record all nameplate information for the induction motor. Additionally, linear induction motors are reversible and can also be dynamically braked. Pressed and held between end plates, these laminations are stacked. Now days almost present of induction motors are squirrel cage type, because this type. The national electrical manufacturers association nema has specified the motors according to the various class, which are discussed below in detail. 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. List and describe the more commonly used equipment in an electric substation. The ac induction motor is by far the most commonly used motor because its relatively simple and can be built at less cost than other types. The squirrel cage induction motor being simple, rugged, and cheap and requiring less maintenance, has been widely used motor for fixed speed application. There are mainly two types of induction motor on the basis of power supply, single phase induction motor and three phase induction motor.