Wound rotor induction motors ac motors electronics. It is expressed by the percentage of synchronous speed. Slip power recovery system in three phase slip ring. The torque produced by the induction motor is directly proportional to induction motor slip. Induction motors have been ruling the industrial world for many decades. Squirrel cage wound rotor with slip rings the rotating magnetic field. Rotor side control of high power slip ring induction motor. Makwana and others published three phase slip ring induction motor drive with slip power control analysis for different. It also requires meticulous and periodic maintenance of the brushes, brush gear, sliprings, external rotor resistances etc. Nov 27, 2019 the three phase induction motor is the most widely used electrical motor. Lecture 6 three phase induction motors cairo university.
Wound rotor induction motor the engineering projects. Speed control of wound rotor induction motor using rotor resistance control aim to use variable resistance in the rotor circuit to control wound rotor induction motor speed theory polyphase induction motors are mainly of two types by construction, squirrel cage and woundrotorwith slip rings. Slip ring induction motor application slip ring induction motor provides high starting torque. Ummu salma ap objective a computer based protection system has been introduced to monitor the various faults of the induction motors and it is achieved with the help of the microcontroller. Almost 80% of the mechanical power used by industries is provided by three phase induction motors because of its simple and rugged construction, low cost, good operating characteristics, the absence of commutator and good speed regulation. Wound rotor induction motors chapter ac motors pdf version. Pdf this work has developed a steadystate and dynamic mathematical model of three phase slipring induction motors with external impedance find, read. 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. Main motor stator terminal is connected to the supply main and the slip power of main motor is fed to the stator terminals of auxiliary induction motor through slip ring as shown in figure below. It is very commonly used in industries because it is very cheap, robust, efficient, and reliable. Higher protection classes can be realized on request at any time. The induction motor stator resembles the stator of a revolving field, three phase alternator.
Slip ring motor conversion to vsd driven standard squirrel. Diagnostics of rotor and stator problems in industrial induction motors by fang duan b. Already since 1927, we are a global manufacturer, supplier, and distributor of large slip ring motors up to 15000 kw and,8 kv. The motor takes its name from the shape of its rotor windings a ring at. So, this motor is used in applications like lifts, pumps, mills where we require high starting torque. Therefore slip ring induction motors are generally employed where load requires high starting torque or good speed control. Fault identification of 3phase slip ring induction motor. Slip ring induction motors slip ring motor starter moflon.
All motors comply with the following indian and international standards. The squirrel cage induction motor is the most popular type of ac motor. This does not involve the power from on rotor side be fed back to the source. 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.
The slip in an induction motor is the difference between the main flux speed and their rotor speed. In squirrel cage induction motors the rotor is simplest and most rugged in construction. Compared to squirrel cage rotor the rotor construction is not simple. Generally, induction motor provides low starting torque as compared to d.
Induction motor seminar ppt, pdf report study mafia. Based on the construction of rotor part the 3phase induction motors are divided into two types. Motors employing this type of rotor are known as squirrelcage induction motors. Slip power recovery system for variable speed operation of. The rotor is the rotating part of the induction motor and is mounted on the shaft of the motor to which any mechanical load can be connected. If the 3phase slip ring induction motor is started as a normal motor with the slip rings shorted, due to low starting torque of slip ring motor, the motor will draw high current i. Menzel 3phase slip ring induction motors in protection class ip 55 are designed in the ic 411 cooling class. The rotor is the rotating part of the motor, whereas the stator works as the stationary part. Good performance, such as high safety, energy saving, compact design, low noise, little vibration, high torque big breakaway torque, reliable operation, stable running and convenient maintenance. Slip ring induction motor slip ring induction motor. These motors are having the difference in rotor construction. 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 rotor circuit. Maruthi prasad and others published rotor side control of high power slip ring induction motor using a single.
Telecommunication engineering, southwest jiaotong university, china, 2005 thesis submitted for the degree of masters of engineering science in school of electrical and electronic engineering the university of adelaide, australia august 2010. Dec 23, 2018 in the case of slip ring induction motor, the construction of stator and rotor is similar. The stator or the stationary part consists of three phase winding held in place in the slots of a laminated steel core which is enclosed and supported by a cast iron or a steel frame as shown in fig. Starting and speed control of 3phase slipring induction. What are slip rings and why do some motors use them. General purpose slipring induction motors product catalogue. Vibrations amplifications on the unsupported shaft extensions of the rotors. 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. Three phase supply brush stator windings rotor windings slip rings running position. An induction motors rotor can be either wound type or squirrelcage. Figure 4 shows the torquespeed characteristics of slip ring induction motor in modified static kramer drive.
Their sole purpose is to allow resistance to be placed in series with the. Three phase slip ring induction motor my tech info. A slipring motor is expensive, as are its controls, compared to a squirrel cage motor. But in an induction motor only the stator winding is fed with an ac supply. 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. These motors are usually started with full line voltage applied across its terminals. Low and high voltage three phase induction motors m line slip ring. Terms used in wound rotor slip the difference between a motors synchronous speed and its speed at full load. A wound rotor motor uses three slip rings typically made of copper or a copper alloy mounted to but insulated from the motor shaft.
Carbon brush performance on slip rings mining electrical. Based on the construction of the rotor, induction motors are broadly classified in two categories. Squirrelcage rotor almost 90 per cent of induction motors are squirrelcage type, because this type of rotor has the simplest and most rugged construction imaginable and is almost indestructible. Slip ring motor fundamentals bright hub engineering.
In fact, until about 1985, a wound rotor induction motor was the only large ac motor that controlled starting characteristics and adjustable speed capability. For applications that demand high starting torques, low starting current, or both, baldor is proud to offer abbs broad line of slip ring induction motors. In the induction motors used in lift and hoists, you will see a type of rotor called a slip ring. A stator winding is placed in the stator of induction motor and the three phase supply is given to it.
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 rotor core is made up of steel laminations which have slots to accommodate formed 3single phase windings. It can improve mechanical performance, simplify system operation and eliminate damageprone wires dangling from. There is a little gap between the stator and rotor called an airgap. Percent slip is a way to measure the speed performance of an induction motor. The slip ring induction motors usually have a phasewound rotor. Slip in induction motor is the relative speed between the rotating magnetic flux and rotor expressed in terms of per unit synchronous speed. Slip ring induction motors for applications that demand high starting torques, low starting current, or both, baldor is proud to offer abbs broad line of slip ring induction motors. In this way, the slip power of main motor is fed to the auxiliary induction motor at a frequency of f 2 s 1 f 1. Induction motors the singlephase induction motor is the most frequently used motor in the world most appliances, such as washing machines and refrigerators, use a singlephase induction machine highly reliable and economical figure 1 singlephase induction motor. Squirrel cage induction motor slip ring induction motor 2. The slip ring induction motor could be used for industrial wires where variable speed and high starting torque are prime requirements. This work has developed a steadystate and dynamic mathematical model of three phase slip ring induction motors with external impedance. The construction of stator of the induction motor is almost the same as other motors.
Generally, it is known as the asynchronous motor because its running speed is less than its synchronous speed. Dec 19, 2017 in this video you will learn connection of slip ring motor with starter panel now you can join our whatsapp group. Apr 11, 2017 induction motors generally will have low starting torque compared to dc series motor. I will tell about the construction of a wound rotor later in this article. Slip ring induction motor working principle electrical mastar. Is the rotor current in a slip ring induction motor. A wound rotor induction motor is also known as slip ring induction motor. This type of rotor is provided with a 3phase, doublelayer, distributed winding consisting of coils used in alternators. Wound rotor induction motor applications how it works wound rotor motors are an extremely versatile breed of induction motors. In contrast, the synchronous motor does not rely on slip induction for.
What are the applications of a slipring induction motor. In slip ring induction motors the rotor is wound type. This technique of starting the motor, permits external resistance to. A slip ring is an electromechanical device that allows the transmission of power and electrical signals from a stationary to a rotating structure. Slip ring induction motor advantages and disadvantages. In this project we are going to start and control the speed of 3phase slip ring induction motor. Therefore those ways for starting the induction motors are used. The main methods employed for speed control of induction motors are as follows. Rotor side control of high power slip ring induction motor using a single thyristor. Slip ring modular motors from abb, availability for heavy load inertia applications. Slip of induction motor plays an important role in the operation of the induction motor. Traditionally, speed control of slip ring induction motor was achieved through varying the rotor resistance. Our design experience and application expertise have made us a leading manufacturer of high voltage slipring inductionmotors.
Slip ring induction motor have big advantage of having high starting torque compared to squirrel cage motor. The rotor of the slip ring induction motor is also cylindrical or constructed of lamination. Dec 19, 2016 slip ring motors are normally used where additional torque is required to overcome the inertia of the load. Slip ring motor conversion to vsd driven standard squirrel cage ac motor by j van niekerk, zest weg group over a number of years slip ring motors have largely been replaced by standard squirrel cage ac induction motors, often in conjunction with ac variable speed drives vsds. The rotor winding terminals are connected to three slip rings which turn with. Generally we all are know induction motor is most widely used motor in industrial. Free download induction motor seminar ppt, pdf report. It is logical that the least expensive, lowest maintenance type motor should be used most often.
Jul 07, 2018 these motors are usually started with full line voltage. Slip rings a conductive device attached to the end of a wound rotor that conducts current to the brushes. Induction motors generally will have low starting torque compared to dc series motor. The starting of a slip ring induction motors is done with a full line voltage because, any desired external resistance can be added very easily to the rotor circuit due to the presence of slip rings. Motors employing this type of rotor are variously known as phasewound motors or wound motors or as slipring motors. Slip ring motors are the motors of choice whenever high starting torque or low starting current are required. The aim behind the development of the project is to limit the current at starting of motor and to develop the high starting torque. The stator construction is the same in both motors. Featuring a rugged design, these machines provide the unique ability to gradually bring up to speed highinertia equipment and large loads smoothly and easily. In this article, we will learn about squirrel cage and slip ring induction motors.
When external resistance initially having zero resistance is shorted with the slip rings, the inherent torque slip curve of the machine gives a speed. Speed control of wound rotor induction motor using rotor. Today, i am going to tell you about a wound rotor induction motor, which is also a type of 3 phase induction motor. If this manual is lost, an electronic pdf file is available at. Advantages and disadvantages of slip ring induction motor. Starting of slip ring induction motor explained in an easy.
An ac motor is an electric motor driven by an alternating current ac. There are different methods of starting of 3phase slip ring induction motor. The rotor winding terminals are connected to three slip rings which turn with the rotor. A simple and primitive method of speed control of a wound rotor induction motor is by mechanical variation of the rotor circuit resistance at output slip terminals. The rotor of the slip ring induction motor is connected to the external resistances. In a version of the ac induction motor referred to as a wound rotor motor, slip rings are used not for transferring power, but for inserting resistance into the rotor windings. Our design experience and application expertise have made us a leading manufacturer of high voltage slip ring. The scheme is somewhat analogous to a primitive kramer system, where a dc motor is coupled to the induction motor shaft and is fed by the rectifier slip power through a diode rectifier. The main advantage of slip ring induction motor over the squirrel cage induction motor is that it consist. But the rotor construction differs with respect to the type of motor.
A slip ring can be used in any electromechanical system that requires rotation while transmitting power or signals. Diagnostics of rotor and stator problems in industrial. Slip ring induction motor working principle electrical. Threephase induction motors are the most common and frequently encountered machines in industry simple design, rugged, lowprice, easy maintenance wide range of power ratings. Sometimes 2 additional for shunt field terminals cabinet type and position dc field supply required. Squirrel cage motors have a rotor with short circuited bars whereas slipring motors have wound rotors having three windings each connected in star. Three phase slip ring induction motor a wound rotor or slip ring motor has a 3phase winding, similar to the stator winding. 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. Pdf three phase slip ring induction motor drive with. Slip ring motors contents product description 62 overview of technical data 64 motor selection data series srspr variablespeed slip ring motors, continuous duty s1 65 series shsph version for crane applicationsiron and steel works, duty types s3, s4s5 67 bearings 626 terminal boxes 631 dimensions 634 6. Differential equations are solved using computer simulation. Portland slip ring induction motorsbrush holder problems and. Adjusting the resistance allows control of the speedtorque characteristic of the motor.
But how does external resistance aid in better starting characteristics. The rotor is normally connected over a 3 stage resistor bank. A wound rotor or slip ring motor has a 3phase winding, similar to the stator winding. They are especially suitable for heavy load inertia applications. When the motor is started the total external resistance get added in the rotor winding resistance and the value of the resistances get gradually decreased with th. Learn more about the construction and operation of a slip ring induction motor. The generally humidityprotected motor winding is designed to be in thermal class f and is impregnated using the vpi process. Read here to know about the starting arrangement and the role played by the external resistances in obtaining better starting characteristics.
Construction of three phase induction motor electrical4u. Slip ring induction motor fundamentals pnpntransistor. The slip ring motor has very little application in industries. What happens if slip rings are short circuited in a 3. Starting torque of slip ring motor and induction motor with. Squirrel cage induction motor vs slip ring induction motor. So obviously the speed of an induction motor can be controlled by varying any of three factors namely supply frequency f, number of pole p or slip s. The value of slip at full load varies from 6% in case of small motor and 2% in the large motor. Abb library is a web tool for searching for documents related to abb products and. This article is devoted to slip ring induction motors. The value of slip in induction motor is can never be zero. A slipring motor also requires a larger space for the motor and its controls. There are two main parts of an induction motor named as the rotor and the stator. Slip ring induction motor is made up from wound rotor and squirrel cage induction motor is made up from the squirrel cage rotor.
Motor archived 20121118 at the wayback machine 2011, the case files. Be specially designed for energy saving purpose which is totally enclosed and fancooled type. Oct 04, 2017 how motors work for beginners episode 3. Squirrel cage motors are normally more efficient than slipring motors, and higherspeed. Wound rotor induction motor variable speed three phase windings in stator rotating magnetic field three phase windings in rotor three phase variable frequency current induced in rotor rotor current brought out to variable resistanceelectronic controls through brushes on three slip rings to control speed. Also know about the qualities of slip ring induction motors. The basic idea of an electric motor is to generate two magnetic fields. Wound rotor induction motors wrim have been popular for decades in the cement and mining industry for starting and driving large grinding mills. An induction motor can therefore be made without electrical connections to the rotor. Speed control of induction motors the speed of an induction motor is given as n 120fp 1s. A slip ring induction motor can be started with external resistance added in its rotor circuit. Slip ring induction motors 5kw slip ring motor motco make slipring induction motors are nearly the same as normal induction motors, except that their rotors are wound with windings. Wound rotor with slip rings the rotating magnetic field.
Three phase induction motors electric motors bharat bijlee. Safe area motors motors for general application cga1d standard squirrel cage tefc motors. Methods of speed control of induction motor electrical. Slipring motors are still used in many branches of industry, and their particular. In a dc motor, supply is needed to be given for the stator winding as well as the rotor winding. Pdf rotor side control of high power slip ring induction motor. 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.
Therefore slip ring induction motors are generally e. Why we need to start induction motor using a starter or with one of starting methods. The value of slip in induction motor at full load varies from about 6% for small motors to about 2% for large motors. Rarely 5% 10% slip ring motors are used in industries because it has several disadvantages like it required. Severe arcing between the brushes and collector rings. Once the inertia of the load is overcome the rotor is shorted and at that time it is running like an induction motor. Low and high voltage three phase induction motors slip ring rotor fixed brushholderm line date. The terminals of the rotor windings of the slipring motors. Woundrotor motors can be started with low inrush current, by inserting high resistance. Stator winding can be either star or delta connected depending upon the design.
As its name indicates stator is a stationary part of induction motor. A squirrel cage motor is thus preferred to a slipring motor. As discussed earlier, a slip ring induction motor is an asynchronous motor, as the rotor never runs in synchronous speed with the stator poles. Search weglowandhighvoltagethreephaseslipringrotor.
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