The torque produced by the induction motor is directly proportional to induction motor slip. 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. Regulation of 3phase alternator by zpf and asa methods 9. Based on type of phase supply three phase induction motor self starting in nature single phase induction motor not self starting other squirrelcage induction motor slip ring induction motor. The value of slip at full load varies from 6% in case of small motor and 2% in the large motor. The induction motor block implements a threephase induction motor. Fullload slip varies from less than 1 % in high hp motors to more than 56 % in minor hp motors. There are two types of induction motors, one with wound type rotor, also called slipring motor and another one with squirrelcage rotor. The corresponding performance curves are plotted when selecting torquesee generator. Aug 24, 2018 induction motor is a wellknown device which works on the principle of transformer. Wound rotor induction motors ac motors electronics. Most of the application of industrial as well as domestic are this type of induction motor. Equivalent circuit for an induction motor electrical4u. These curves show that the slip at maximum torque s remains same, while the value of stall torque comes down with decrease in applied voltage.
The tendency of the rotor teeth to remain under the stator teeth due to direct magnetic attraction is reduced. Such properties include a number of poles, speed, frequency, slip, starting current and rated horsepower. Threephase induction motors are the most common and frequently. This may be achieved by converting a singlephase supply into twophase supply through the use of an additional winding. As its name indicates stator is a stationary part of induction motor. Principle of operation, development of equivalent circuit, derivation of torque expression are discussed in sequence. The single phase induction motors are clas sified based on method of starting. An induction motor can therefore be made without electrical connections to the rotor. In this paper a slip compensator, based on fuzzy logic incremental controller has been developed to improve the steady state performance of efficiencyoptimized threephase induction motor drive system. For reason of economy, most houses, offices and also rural areas are supplied with single phase a. The three phase induction motors are simple in construction, rugged, low cost and easy to maintain. Cage induction motor an overview sciencedirect topics. The slip ring induction motor could be used for industrial wires where variable speed and high starting torque are prime requirements.
Torque slip characteristics of induction motor electrical4u. In this paper a slip compensator, based on fuzzy logic incremental controller has been. Worlds best powerpoint templates crystalgraphics offers more powerpoint templates than anyone else in the world, with over 4 million to choose from. An ac motor is an electric motor driven by an alternating current ac. In contrast, the synchronous motor does not rely on slip induction for operation and uses either permanent. Slip in induction motor is the relative speed between the rotating magnetic flux and rotor expressed in terms of per unit synchronous speed. Overhauling 10kw induction motor free download as powerpoint presentation. You should also make a dc measurement of stator winding linetoline resistance using a dmm. The voltage and current is induced in the rotor circuit from the stator circuit for the operation. The most severe type of fault was found to be an opencircuited phase of the load such as may occur in a slip ring motor drive when the brushes bounce. This final thesis will mostly be dedicated to induction motors but also to synchronous permanent magnet and reluctance motors. Concluding, advantage of induction motor is its simple operation, reliability and low cost. It is logical that the least expensive, lowest maintenance type. The stator works as the primary while the rotor works as the secondary.
The terminals of the rotor windings of the slipring motors. Squirrel cage motors have a rotor with short circuited bars whereas slipring motors have wound rotors having three windings each connected in star. That is, when an emf is supplied to its stator, then as a result of electromagnetic induction, a voltage is induced in its rotor. Torque slip characteristics of induction motor also known as torquespeed characteristics provide us with the information about the variation of torque with the slip. Slip is defined as difference between synchronous speed speed of rotation of magnetic field and rotor speed speed of rotatory part of induction motor. Introduction to induction motor the engineering projects. Optimal volume and slip of a three phase induction motor using differential evolution. But electric power is communicated to the rotor by induction. A 480v, 60 hz, 6pole, threephase, deltaconnected induction motor has the. Three phase supply is given to the primary with the help of 3 slip rings. Their sole purpose is to allow resistance to be placed in series with the rotor windings while starting figure below. 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. Overhauling 10kw induction motor insulator electricity.
Stardelta starting of a three phase induction motor 10. An induction motor is based on the principle of induction of voltages and currents. Advantages of slip ring induction motor it has high starting torque and low starting current. An induction motor also known as an asynchronous motor is a commonly used ac electric motor. 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. The variation of slip can be obtained with the variation of speed that is when speed varies the. Free download induction motor seminar ppt, pdf report.
Starting andcontrol of slipring 5 electrical engineering book. The 3phase set of currents, each of equal magnitude and with a phase. 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. Theyll give your presentations a professional, memorable appearance the kind of sophisticated look that todays audiences expect. Slip ring induction motor working principle electrical. By default, the block sets the simulation type parameter to continuous to use a continuous sample time during simulation. The catalogue covers slipring induction motors called also wound rotor induction motors that are applied to start a high inertia load or a load that requires a very.
Before going to the operation and characteristics of splitphase induction motor we should first understand why single phase induction motor is not selfstarting to make a singlephase induction motor selfstarting, we should somehow produce a rotating magnetic field. Record all nameplate information for the induction motor. Generally, it is known as the asynchronous motor because its running speed is less than its synchronous speed. Because this type of motor has a high slip at full load, its speed can be varied by adjusting. Design of a single sided linear induction motor slim using a user interactive computer program a thesis presented to the faculty of the graduate school university of missouricolumbia in partial fulfillment of the requirements for the degree master of science by sarveswara prasad bhamidi dr. 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. Schrage motor is essentially a combination of wound rotor induction motor and frequency convertor. As discussed earlier, a slip ring induction motor is an asynchronous motor, as the rotor never runs in synchronous speed with the stator poles. The induction machine operates between synchronous speed slip 0 and double value of. The slip corresponding to full load speed of th motor is called full load slip. Ppt induction motor powerpoint presentation free to. Winner of the standing ovation award for best powerpoint templates from presentations magazine. The short film ac motors 1969 is available for free download at the internet archive. The block uses the threephase input voltages to regulate the individual phase currents, allowing control of the motor torque or speed.
Jul 11, 2019 the torque slip curve for an induction motor gives us the information about the variation of torque with the slip. The difference, or slip, between actual and synchronous speed varies from about 0. Schrage motor operation principle and characteristics of. Slip compensation in efficiencyoptimized threephase. If the slip is zero, what is the speed of a induction motor. Slip ring induction motor are used where high starting torque is required i. Electrical interview questions which motor is best. In normal operating conditions between pullout speed and synchronous speed we have nearly a linear relationship between the torque and the slip.
Energy efficiency optimization techniques of electrical drive systems improve the overall efficiency and reduce the hardness of mechanical characteristics of the drive system. It is logical that the least expensive, lowest maintenance type motor should be used most often. It is therefore important to reduce the slip of induction motor to maintain its stable operation at different frequencies and loads. The difference between the synchronous speed n s of the rotating stator field and the actual rotor speed n is called slip in a threephase induction motor. The slip of the induction motor varies from 5 percent for small motors to 2 percent for large motors. Possibility of adding additional resistance to control speed. General purpose slipring induction motors product catalogue. Slip in electrical induction motors engineering toolbox. A 4 pole, 3 phase induction motor is supplied from hz supply. Historythe induction motor with a wrapped rotor wasinvented by nikola tesla in. Determination of the losses in induction machines due to harmonics pdf. Number of poles, frequencies and synchronous induction motor speed. 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 the rotor speed increases above base speed.
Unlike induction motor the primary winding of schrage motor is on the rotor. When a motor starts to rotate the slip is 100 % and the motor current is at maximum. The rotor of the slip ring induction motor is also cylindrical or constructed of lamination. An induction motor or asynchronous motor is an ac electric motor in which the electric current. Schrage motor can be treated as an inverted poly phase induction motor. Pdf highslip induction motor with additional rotor moveable. Stator winding can be either star or delta connected depending upon the design. The difference of squirrel cage and slip ring induction motor is mainly on torque, speed, slip, resistance and reactance.
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. Squirrel cage induction motor squirrel cage induction motors are usually used in various industrial applications. Three phase slip ring induction motor my tech info. There are two basic reasons for the use of singlephase motors rather than 3phase motors. Chart and diagram slides for powerpoint beautifully designed chart and diagram s for powerpoint with visually stunning graphics and animation effects. It is expressed by the percentage of synchronous speed. By far the most commonly used ac motor is the induction motor. Slip is usually expressed as a percentage of synchronous speed i. And the variation of the slip obtained with the variation of speed.
If the motor slip is known, the rotor speed can be expressed by the equation. The induction machine operates between synchronous speed slip 0 and double value of the synchronous speed slip 1. It certainly can rotate at synchronous speed, or even faster. 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. The slip is defined as the ratio of difference of synchronous speed and actual rotor speed to the synchronous speed of the machine.
Our new crystalgraphics chart and diagram slides for powerpoint is a collection of over impressively designed datadriven chart and editable diagram s guaranteed to impress any audience. This curve provides us with information about the operation of an induction motor. The value of slip in induction motor is can never be zero. S nsnrnsx100% ns synch speed nr rotor speed sslip slip increase with increase of mechanical load. Slip of induction motor electrical engineering interview. Slipring induction motors in conjunction with rotor resistanceswitching contactors are widely used for ancillary mechanical. The rotor will constantly be turning to align its magnetic field with that of the stator field. 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. Effectively, the rotor is the secondary winding of a transformer, which is driven by a frequency equal to the slip speed. An induction motors rotor can be either wound type or squirrelcage type. Introductionan induction motorim is a type ofasynchronous acmotor where power is supplied to therotating device bymeans ofelectromagneticinduction threephase induction motors 4.
Motor runs smoothly as the magnetic hum is reduced b. May 20, 2018 and from this relation we deduce that curve. Us3372323a induction motor slip frequency control system. Learn more about the construction and operation of a slip ring induction motor. Fault identification of 3phase slip ring induction motor free download as powerpoint presentation. Single phase induction motor double revolving field theory the threephase induction motor starting torque inversely depends on the slip this implies that a small positive slip 0. A disadvantage of the cage induction motor is the large starting current, which is about 5 to. Equivalent circuit of an induction motor enables the performance characteristics which are evaluated for steady state conditions. 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. 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. Split phase induction motor operation and characteristics. To start induction motor by rotor resistance starter 8. Torque slip characteristics of induction motor full guide.
Pdf optimal volume and slip of a three phase induction motor. The difference multiplied with hundred and divisible by the synchronous speed is called the slip percentage. At the synchronous speed slip s0 so, the motor will produce zero torque. The most severe type of fault was found to be an opencircuited phase of the load such as may occur in a slipring motor drive when the brushes bounce. 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. Sep 27, 2016 according to the type of rotor, an induction motor is divided into two types. The value of slip in induction motor at full load varies from about 6% for small motors to about 2% for large motors. Jan 11, 2018 such properties include a number of poles, speed, frequency, slip, starting current and rated horsepower.
A stator winding is placed in the stator of induction motor and the three phase supply is given to it. 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. The maximum torque that the motor can develop typically 2. Lecture 6 three phase induction motors cairo university. The slip in an induction motor is the difference between the main flux speed and their rotor speed. Due to this an induction motor is sometimes referred to as an asynchronous machine. An887, ac induction motor fundamentals microchip technology. A wound rotor induction motor has a stator like a squirrel cage induction motor, but a rotor with insulated windings brought out via slip rings and brushes however, no power is applied to the slip rings. A variable frequency ac induction motor servo control system wherein slip is generated as a function of stator current. The induction machine operates between zero speed slip 1 and synchronous speed slip 0.
When the speed varies the slip vary and in contrast the torque will also var y. Highslip, induction motor, additional rotor, motor cooling. Fault identification of 3phase slip ring induction motor. If slip is zero then their is no relative speed between stator and rotor. Cheap copare to slipring im maintainance is easy cost is less compare to slipring im can use at explosive area starting torque is low compare to slip ring im application. The construction of a stator is the same for both the squirrel cage and slip ring induction motor. The most commonly used is the squirrel cage induction motor. Overview in this module, we first discuss about the types and constructional features of 3phase induction motors. Slip of induction motor plays an important role in the operation of the induction motor. If the slip ring induction motor is started with all the slip rings or the rotor. Us3372323a us44419365a us3372323a us 3372323 a us3372323 a us 3372323a us 44419365 a us44419365 a us 44419365a us 3372323 a us3372323 a us 3372323a authority us united states prior art keywords voltage output frequency slip means prior art date 19650331 legal status the legal status is an assumption and is not a legal conclusion. As we know, the slip speed is the difference between the synchronous and rotor speed of the induction motor. Generally we all are know induction motor is most widely used motor in industrial. Induction motor seminar ppt, pdf report study mafia.
1120 992 1455 1230 1474 1503 37 1160 1297 202 11 376 551 1329 1382 382 505 1560 238 137 491 937 671 1081 763 1344 834 1310 820 688 1041 1394 174 1318 358 531 1193 834