The basic idea of an electric motor is to generate two magnetic fields. By putting resistance in series with the rotor windings, the starting current can be kept low while maintaining good starting torque. Induction motor theory jerry bednarczyk, pe course content introduction the ac induction motor is well suited to applications requiring constant speed operation. The two brushes are connected to a single phase starconnected rheostat as. The construction of a stator is the same for both the squirrel cage and slip ring induction motor.
Working principle of a threephase induction motor rotating. Induction motors and transformers both im and transformer works on the principle of. In a version of the ac induction motor referred to as a wound rotor. 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 this video, i will explain you about the working of the threephase induction motor. The slip ring allows for unlimited rotations of the connected object, whereas a slack cable can only be twisted a few times before it will fail. But in an induction motor only the stator winding is fed with an ac supply. Therefore slip ring induction motors are generally e. In general, the induction motor is cheaper and easier to maintain compared to other alternatives. Production of high starting torque with slip ring induction motor.
Starting of slip ring induction motor explained in an easy manner. A slip ring induction motor can be started with external resistance added in its rotor circuit. The single phase induction motor resembles, threephase, squirrelcage motor except that, single phase induction motor has no starting torque and some special arrangement have to be made to make it as self starting. Therefore, these motors are frequently used in industry. The rotor is separated from the stator by a small airgap which ranges from 0. Advantages and disadvantages of slip ring induction motor. 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. Srim rotor consists of a threephase winding similar to the stator winding, but in scim the rotor consists of bars which are shortened at the ends with help of end rings. You also come to know about the law on which the motor works, the types of field induces on the rotor, and. As previously, we have covered a lot of important topics.
The rotor poles connect to each other and move at the same speed hence the name synchronous motor. Why are there two different designs of rotor construction for induction motors. Generally, it is known as the asynchronous motor because its running speed is less than its synchronous speed. It can improve mechanical performance, simplify system operation and eliminate damageprone wires dangling from movable joints. They run at a constant speed from noload to the full load. Dc motors although ac motors are used in most of the cases, dc motors have many applications and used for multipurpose applications. Jul 11, 2019 this page is about single phase induction motor. Slip in induction motor is the relative speed between the rotating magnetic flux and rotor expressed in terms of per unit synchronous speed. A 3 phase induction motor has two main parts i stator and ii rotor. Proposed circuit diagram of the traction drive system using wrim. The slip ring rotor was developed after a decade or so. By the way, the induction motor is also called an asynchronous motor because it runs at a speed lower than its synchronous speed. The slip ring rotor chamber has two modification openings. In a dc motor, supply is needed to be given for the stator winding as well as the rotor winding.
Contrast this with an induction motor, which must slip in order to produce torque. Free download induction motor seminar ppt, pdf report. Apr 11, 2017 induction motors generally will have low starting torque compared to dc series motor. Oct 04, 2017 3 phase motor with resistance type starter. The rotor winding terminals are connected to three slip rings which turn with the rotor. Advantages and disadvantages of 3 phase induction motors. This article is devoted to slip ring induction motors. Read here to know about the starting arrangement and the role played by the external resistances in obtaining better starting characteristics. Slipring motors are invariably started by rotor resistance starting. The value of slip in induction motor is can never be zero. Stator winding can be either star or delta connected depending upon the design.
Pdf the use of squirrel cage motor for traction has revolutionised the motive power of. In normal conditions, the slip ring motor functions like a squirrel cage motor. Its operation is based on the principle that when a current carrying conductor is placed in a. Three phase slip ring induction motor my tech info.
Induction motor different types of duties in motor construction how induction motor as a rotating transformer how to run three phase motor on single phase power supply induction motor interview question slip ring induction motor srim vs squirrel cage induction motor scim synchronous watt types of encloser employed in induction motor types of insulation class. Slip ring induction motor working principle electrical. 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. Working principle of an induction motor the motor which works on the principle of electromagnetic induction is known as the induction motor. In many industrial variablespeed applications, dc and wrim drives are being displaced by vfdfed cage induction motors. Slip in electrical induction motors slip is the differentiation between synchronous and asynchronous speed. 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. Find the percentage slip and number of poles of the induction motor.
Starting andcontrol of slipring 5 electrical engineering book. The slip in an induction motor is the difference between the main flux speed and their rotor speed. Download 3 phase induction motor powerpoint presentation. Squirrel cage motor and ii slip ring motor or wound type. It is expressed by the percentage of synchronous speed. Squirrel cage wound rotor with slip rings the rotating magnetic field.
The surfacecooling principle in slip ring induction motors ic 411 the standard threephase slip ring induction motor in protection class ip 55 has ic 411 cooling. Slip ring induction motor construction, working, speedcontrol. A synchronous electric motor is an ac motor distinguished by a rotor spinning with coils passing magnets at the same rate as the alternating current and resulting magnetic field which drives it. The slip ring induction motor could be used for industrial wires where variable speed and high starting torque are prime requirements. In this chapter, we shall focus our attention on the construction, working and characteristics of commonly used singlephase motors. The slip ringsbrushes allow external resistors to be connected in series with the winding. Download 3 phase induction motor powerpoint presentation download and read online. Thus the rotor rotates in the same direction as that of stator flux to minimize the relative velocity. 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. Induction motors generally will have low starting torque compared to dc series motor. Starting of slip ring induction motor explained in an easy.
Slipring motor manufacturer menzel provides shortterm availability and adaptation, applicationspecific requirements and worldwide logistics. The rotor will constantly be turning to align its magnetic field with the stator field. Large slip ring motor drives, termed slip energy recovery systems, some still in use, recover energy from the rotor circuit, rectify it, and return it to the power system using a vfd. The slip ring rotor chamber of the ic 411 slip ring induction motor is separated by what is known as a labyrinth seal, which prevents contamination from coal dust. Squirrel cage induction motor slip ring induction motor 2. Working principle of an induction motor circuit globe. Working principle of 3 phase squirrel cage 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.
However, the rotor never succeeds in catching up the synchronous speed. Learn more about the construction and operation of a slip ring induction motor. Introduction types of electrical machines types of 3ph induction motor basic principle working principle compnents of induction motor application comparision between 1ph i. Dc motor principle a machine that converts dc power into mechanical energy is known as dc motor. A three phase, 12 pole, salient pole alternator is coupled to a diesel engine running at 500 rpm. Slip of induction motor plays an important role in the operation of the induction motor. This is the basic working principle of induction motor of either type, single phase of 3 phase. The slip ring induction motor working in the induction principle. We can react very quickly due to a comprehensive stock of slip ring motors in a power range up to 15000 kw.
As discussed earlier, a slip ring induction motor is an asynchronous motor, as the rotor never runs in synchronous speed with the stator poles. Liquid speed controllers can be supplied to provide required slip resistance to the slip ring motors for speed variation special sized electrolyte tank and heat exchangers are provided to dissipate the heat energy generated in electrolyte during variation of speed. However, even before i do that, it is important to know the various parts of the induction motor. A single phase induction motor has two types of rotor. 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.
What is synchronous motor and types electrical mastar. Srim rotor construction is very complicated but in scim the rotor construction is. Feb 07, 2018 in this video, i will explain you about the working of the threephase induction motor. What is the working principle of slip ring induction motor. 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 electromagnetic induction is the phenomenon in which the electromotive force induces across the electrical conductor when it is placed in a. However, even before i do that, it is important to know the. In this article, i am going to focus on the working principle of the induction motor. Slip rings and brushes are used to conduct current to the rotor. Slip ring motor manufacturer menzel provides shortterm availability and adaptation, applicationspecific requirements and worldwide logistics. Slip ring induction motor srim vs squirrel cage induction. Also know about the qualities of slip ring induction motors. A slip ring is an electromechanical device that allows the transmission of power and electrical signals from a stationary to a rotating structure.
Adjusting the resistance allows control of the speedtorque characteristic of the motor. Induction motors are the most commonly used motors in most of the applications. This cooling type corresponds to the design of a surfacecooled motor with a housing featuring cooling fins and an external fan mounted on the shaft. To overcome this problem, the slip ring induction motor comes into the picture. The rotor of the slip ring induction motor is also. Slip ring induction motor are used where high starting torque is required i. The page also answers why single phase induction motor is not selfstarting and also tells methods for making it as a selfstarting motor. A woundrotor motor, also known as slip ring rotor motor, is a type of induction motor where the rotor windings are connected through slip rings to external resistance. Before discussing the theory of operation for the induction motor a very basic. The principle of operation of the induction machine is. In the induction motors used in lift and hoists, you will see a type of rotor called a slip ring rotor, whereas in most of the other applications you will see a simpler, squirrel cage type of rotor.
A slip ring can be used in any electromechanical system that requires rotation while transmitting power or signals. Today we are going to made available a powerpoint presentation file for all. A wound rotor or slip ring motor has a 3phase winding, similar to the stator. But how does external resistance aid in better starting characteristics. What are slip rings and why do some motors use them.
By putting resistance in series with the rotor windings, the starting current can be kept low while mainta. The induction motor is made up of the stator, or stationary windings, and the rotor. As these motors have external resistance connected to its rotor circuit, the value of starting current is adjusted or kept minimum, by increasing the resistance of the. This means that the state of the carbon brushes and the slip ring rotor can be monitored, and cleaning can take place. The torque produced by the induction motor is directly proportional to induction motor slip. Thus from the working principle of three phase induction motor, it may be observed that the rotor speed should not reach the synchronous speed produced by the stator. Another way of saying this is that it has zero slip under usual operating conditions. What are the applications of a slipring induction motor. Slip ring induction motor have big advantage of having high starting torque compared to squirrel cage motor. If the speeds become equal, there would be no such relative speed, so no emf induced in the rotor, and no current would be flowing, and therefore no torque would be generated.
The singlephase stator winding produces a magnetic field that pulsates in strength in a. An induction motor can therefore be made without electrical connections to the rotor. Nov 27, 2019 thus from the working principle of three phase induction motor, it may be observed that the rotor speed should not reach the synchronous speed produced by the stator. Maximum starting can be attained in the slip ring motor compared to squirrel cage motor by inserting an external resistance in each phase of the rotor circuit and cutting the resistance during starting speeds can be adjusted in the case of slip. At noload, the slip is nearly zero slipring induction motors5 97 the use of wound motors is on the wane, for reasons of inherent advantages of a squirrel cage motor over a wound motor and the availability of static drives which can make a squirrel cage motor perform the same duties as a wound motor and even better. Ppt induction motor powerpoint presentation free to. Jul 24, 2017 the direct current can be supplied from a separate source or from a dc generator directly connected to the motor shaft. It supplies an induction motor ich has a full load speed of 144wh 0 rpm. Pdf design and analysis of drive system with slip ring induction. Induction motor seminar ppt, pdf report study mafia. The three phase induction motors are simple in construction, rugged, low cost and easy to maintain. The page includes the construction, working principle of single phase induction motor. The working principles and stator construction of the slip ring induction motor are exactly the same as that of the squirrel cage motor.
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. Slip in electrical induction motors engineering toolbox. Woundrotor motors can be started with low inrush current, by inserting high resistance into the rotor circuit. Slip ring motor fundamentals brighthub engineering. Slip ring induction motor srim vs squirrel cage induction motor scim. Slip ring induction motor working principle electrical mastar.
1163 392 1196 488 826 16 1380 92 636 1143 964 280 1002 305 1130 203 341 618 790 360 933 48 72 1365 998 1491 1438 1142 1304 98 908