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. Jan 02, 2020 the resistance of the squirrelcage induction motor can not be varied as compared to the slip ring induction motor. Free download induction motor seminar ppt, pdf report. Slip in induction motor is the relative speed between the rotating magnetic flux and rotor expressed in terms of per unit synchronous speed. Three phase slip ring induction motor my tech info. The construction of a stator is the same for both the squirrel cage and slip ring induction motor. Induction motor seminar ppt, pdf report study mafia. Induction motor theory jerry bednarczyk, pe course content introduction the ac induction motor is well suited to applications requiring constant speed operation. As discussed earlier, a slip ring induction motor is an asynchronous motor, as the rotor never runs in synchronous speed with the stator poles. Its starting torque is somewhat inferior to that of a d. Inductive reactance depends on the frequency and the slip. Slip ring induction motor have big advantage of having high starting torque compared to squirrel cage motor.
This is a rotating machine, unlike the transformer, described in the previous. A stator is in all the motor only winding on the stator is vary with types of motor. Slip ring induction motor is made up from wound rotor and squirrel cage induction motor is made up from the squirrel cage rotor. An induction motor is dependent on electromagnetic induction thus the name to produce torque. Slip of induction motor plays an important role in the operation of the induction motor. The 3phase set of currents, each of equal magnitude and with a phase. This means that lines of magnetic force must move through conductors in a closed circuit, inducing current in those conductors in order to produce a ma. In the rotor resistance control method, the slip power in the rotor circuit is wasted as i 2 r losses during the lowspeed operation.
The three phase induction motors are simple in construction, rugged, low cost and easy to maintain. Slip ring induction motor application, construction, working principle, advantages and disadvantages, speed control of slip ring induction motor, the difference between slip ring i. Slip in electrical induction motors engineering toolbox. Slip in electrical induction motors slip is the differentiation between synchronous and asynchronous speed an ac alternating current induction motor consists of a stator and a rotor and the interaction of the currents flowing in the rotor bars and the rotating magnetic field in the stator generates the torque that turns the motor. Slip ring induction motors are usually started by connecting starting resistance in the secondary circuit, which are shorted out as the motor speed up. Three phase induction motor is a particular form of transformer which has secondary winding rotating. Torque slip characteristics of induction motor electrical4u. Jul 11, 2019 torque slip characteristics of three phase induction motor the torque slip curve for an induction motor gives us the information about the variation of torque with the slip.
Pdf this research focuses on the problem of selfcooled highslip induction motors, particularly on the problem of their overheating, when. This article is devoted to slip ring induction motors. Squirrel cage motors have a rotor with short circuited bars whereas slipring motors have wound rotors having three windings each connected in star. 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. An induction motor also known as an asynchronous motor is a commonly used ac electric motor. 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.
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. And the variation of the slip obtained with the variation of speed. The slip is defined as the ratio of difference of synchronous speed and actual rotor speed to the synchronous speed of the. Oct 04, 2017 typical torque speed characteristics of induction motor when supplied from variable voltage at rated frequency are given in fig. They are based on the fact that the induction motor torque at a given slip varies as the square of the voltage. Malagoli and others published optimal volume and slip of a three phase induction motor using differential evolution find, read. The rotor will constantly be turning to align its magnetic field with that of the stator field.
Jan 11, 2018 such properties include a number of poles, speed, frequency, slip, starting current and rated horsepower. But the rotor construction differs with respect to the type of motor. Learn more about the construction and operation of a slip ring induction motor. S nsnrnsx100% ns synch speed nr rotor speed sslip slip increase with increase of mechanical load. Torque slip characteristics of induction motor your. The torque produced by the induction motor is directly proportional to induction motor slip. Torque slip characteristics of induction motor full guide. Torque slip characteristics of induction motor also known as torquespeed characteristics provide us with the information about the variation of torque with the slip. You should also make a dc measurement of stator winding linetoline resistance using a dmm. The quantity nsn is sometimes called as slip speed. 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. 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. Torque speed characteristics of induction motor slip power. Diagnostics of rotor and stator problems in industrial.
Slip ring induction motor fundamentals pnpntransistor. Construction an induction motor consists essentially of two main parts. A wound rotor or slip ring motor has a 3phase winding, similar to the stator winding. As we know, the slip speed is the difference between the synchronous and rotor speed of the induction motor.
Slip and motor current are reduced when the rotor begin turning. The basic idea of an electric motor is to generate two magnetic fields. Slip compensation of induction motor using sensorless control ieice. The slip ring induction motor could be used for industrial wires where variable speed and high starting torque are prime requirements. This method is also known as static scherbius drive. What are the applications of a slipring induction motor. Pdf optimal volume and slip of a three phase induction motor. If the slip ring induction motor is started with all the slip rings or the rotor terminals. 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. The slip for maximum torque is independent of voltage.
How an induction motor works by equations and physics. If you want to know about the slip ring induction motor. The value of slip in induction motor at full load varies from about 6% for small motors to about 2% for large motors. Diagnostics of rotor and stator problems in industrial induction motors by fang duan b. When the speed varies the slip vary and in contrast the torque will also var y. A 480v, 60 hz, 6pole, threephase, deltaconnected induction motor has the. 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. The value of slip in induction motor is can never be zero. In the squirrelcage induction motor, the rotor has very low fixed resistance, therefore, the starting torque is low due to low power factor and high reactance. The singlephase induction motor is the most frequently used motor for refrigerators, washing machines, clocks, drills, compressors, pumps, and so forth. The induction motor is made up of the stator, or stationary windings, and the rotor.
Lastly, the expression of maximum torque developed and the slip speed at which it occurs, are derived. Slip energy recovery of an induction motor circuit globe. An induction motor can therefore be made without electrical connections to the rotor. It is logical that the least expensive, lowest maintenance type motor should be used most often. In general, the induction motor is cheaper and easier to maintain compared to other alternatives. Torque slip characteristics of three phase induction motor the torque slip curve for an induction motor gives us the information about the. To draw the torque slip characteristics of induction motor three phase following points are considered at synchronous speed n s.
Torqueslip speed characteristics of induction motor nptel. Wound rotor induction motors ac motors electronics textbook. To understand the torque slip characteristics of induction motor we should focus on mathematics relations. Overview in this module, we first discuss about the types and constructional features of 3phase induction motors. Slip is defined as difference between synchronous speed speed of rotation of magnetic field and rotor speed speed of rotatory part of induction motor. Apr 11, 2017 induction motors generally will have low starting torque compared to dc series motor. Principle of operation, development of equivalent circuit, derivation of torque expression are discussed in sequence. This curve provides us with information about the operation of an induction 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. Pdf highslip induction motor with additional rotor moveable. 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 ring motor fundamentals brighthub engineering. The stator is the outer component of the motor which can be seen. Record all nameplate information for the 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. Generally, it is known as the asynchronous motor because its running speed is less than its synchronous speed. The construction of stator of the induction motor is almost the same as other motors. Slip energy recovery of an induction motor slip energy recovery is one of the methods of controlling the speed of an induction motor. A 3 phase induction motor can be used for different applications with various speed and load requirements. The slip of the induction motor varies from 5 percent for small motors to 2 percent for large motors. 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.
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