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standard squirrel cage ac motor by j van niekerk, zest weg group over a number of years slip ring motors have largely been replaced by standard squirrel cage ac induction motors, often in conjunction with ac variable speed drives vsds. Advantages and disadvantages of slip ring induction motor. The atv71 has to cover the full motor load, make sure the continuous output current of the drive is higher than motor load current. Portland slip ring induction motorsbrush holder problems and. The slip ring induction motor working in the induction principle. This means that the state of the carbon brushes and the slip ring rotor can be monitored, and cleaning can take place. Oct 04, 2017 3 phase motor with resistance type starter.
Draw the torque slip characteristics of 3 phase slip ring induction motor. Slip energy recovery of an induction motor circuit globe. 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 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. Is it possible to use slip ring motor with altivar 71 drive. Slip rings are used to connect a wound rotor to external resistance. Single phase induction motor, theory of operation double revolving field theory, equivalent circuit, determination of. Hence slip ring motors are used where one or more of the above requirements are to be met. Rotor side control of high power slip ring induction motor. It is very commonly used in industries because it is very cheap, robust, efficient, and reliable. General purpose slipring induction motors product catalogue. Stator winding can be either star or delta connected depending upon the design.
An induction motors rotor can be either wound type or squirrelcage. The 3phase set of currents, each of equal magnitude and with a phase. In traditional designs of 60 hz linefed induction machines, skin effect is. Squirrel cage rotor wound type rotor or slip ring type rotor squirrel cage rotor in this type. If the ohmic values of these resistances are properly chosen and if the resistors are designed for continuous operation, they can serve dual purpose i. The slip ring motor has very little application in industries. Slip energy recovery of an induction motor slip energy recovery is one of the methods of controlling the speed of an induction motor. As a slip ring induction motor starts, the external resistance value is increased fig.
The application of induction motor differs by the type of rotor which is being used squirrel cage rotor. In general, this means that, regardless of whether they start loaded or have great inertia, slip ring induction motors are commonly used in the drives with a diffi cult. High voltage motors for conveyors english pdf leaflet. Record all nameplate information for the induction motor. Users occasionally inquire as to the feasibility of converting an existing woundrotor moto. The slip rings brushes allow external resistors to be connected in series with the winding. Induction machines, which have these kinds of windings and terminals that are brought out, are called slip ring machines. Dc motors although ac motors are used in most of the cases, dc motors have many applications and used for multipurpose applications.
Design and analysis of drive system with slip ring induction motor for electric traction in india. 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. What are the functions of sliprings in induction motor. In the process of selecting a suitable motor for a cement mill, there are several issues to consider that, for the purpose of analysis, can be grouped into two distinct categories. Induction motor theory jerry bednarczyk, pe course content introduction the ac induction motor is well suited to applications requiring constant speed operation. Slip ring motor fundamentals bright hub engineering. 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.
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. This can be used in starting a slipring induction motor, for example. How can i find the slip speed of a slip ring induction. The rotor can be wound a threephase star or delta winding, distributed winding, wound for the same as that of the stator of the motor. In cranes, hoists and tractions basically slip ring induction motor is designed to overcome the drawback in squirrel cage induction motor which is low starting torque. The rotor of the slip ring induction motor is also cylindrical or constructed of lamination. The principle of operation of the induction machine is based. Speed control of three phase slip ring induction motor 10. The motors described in this guide all operate on the principle. Pdf this work has developed a steadystate and dynamic mathematical model of three phase slipring induction motors with external impedance find, read. Induction motors generally will have low starting torque compared to dc series 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. 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.
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. Slip ring induction motor working principle electrical. Coming to practical world, many industries operate with slip ring induction motor for high starting torque application. 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. Slip ring induction motor working principle electrical mastar. As discussed earlier, a slip ring induction motor is an asynchronous motor, as the rotor never runs in synchronous speed with the stator poles. So, this motor is used in applications like lifts, pumps, mills where we require high starting torque. We can react very quickly due to a comprehensive stock of slip ring motors in a power range up to 15000 kw. The least expensive and most widely spread induction motor is the socalled squirrel cage motor. 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. Adjusting the resistance allows control of the speedtorque characteristic of the motor. Production of high starting torque with slip ring induction motor. Calculate the slip speed at which max torque occurs. The voltage and current is induced in the rotor circuit from the stator circuit for the operation.
A metal ring at the ends resulting in a short circuit connects the. Slipring modular motors from abb, availability for heavy load inertia applications english pdf leaflet product note. C series motors but this disadvantages of the induction motor can be overcome by slip ring induction motor. Single phase induction motor, theory of operation double revolving. Abb slipring modular motors abb high voltage induction. Pdf three phase slip ring induction motor drive with. Differential equations are solved using computer simulation. The capacitor motor, which belongs to the singlephase induction motor, is explained in this video. How to convert a slip ring motor into squirrel cage motor quora. In this type of induction motors, the rotor comes with the separate winding section as similar to stator of the motor.
The most basic ways to control the speed of a slip ring induction motor is either from the stator or rotor side. Starting of slip ring induction motor explained in an easy manner. Mar 04, 2016 slip ring or phase wound induction motor squirrel cage induction motor construction is complicated due to presence of slip ring and brushes construction is very simple the rotor winding is similar to the stator winding the rotor consists of rotor bars which are permanently shorted with the help of end rings we can easily add rotor resistance by. State the condition for maximum torque of 3phase induction motor. The construction of a stator is the same for both the squirrel cage and slip ring induction motor. Skin effect causes nonuniform distribution of current in the conductor current density in the rotor bar is higher closer to airgap. 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. Equivalent circuit of an induction motor enables the performance characteristics which are evaluated for steady state conditions. Also know about the qualities of slip ring induction motors. The rotor winding terminals are connected to three slip rings which turn with the rotor. A typical asynchronous motor is shown in figure 71. Induction motors have been ruling the industrial world for many decades. What is slip ring induction motor practical explanation. State the steps to draw the equivalent circuit of 3phase induction motor.
Also check the slip ring motor current and select atv 71 drive one or two step oversize. Slip of induction motor plays an important role in the operation of the induction motor. Dc motor principle a machine that converts dc power into mechanical energy is known as dc motor. Traditional design of cage rotor induction motors ronald g. Be careful it can hurt to tangle with a threephase motor. Starting and speed control of 3phase slipring induction. Ysalient features y robust and nonflammable construction. Why we need to start induction motor using a starter or with one of starting methods. Pdf the use of squirrel cage motor for traction has revolutionised the motive. The torque produced by the induction motor is directly proportional to induction motor slip.
No name of experiment page no 1 to perform the brake test on a 3 slip ring induction motor and obtain its performance characteristics 2 to start a 3phase slip ring induction motor by rotor resistance starter. Slip ring motor conversion to vsd driven standard squirrel. We develop appropriate solution with characteristic lines that match precisely your specifications and demands for your application. 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. By putting resistance in series with the rotor windings, the starting current can be kept low while mainta. Calculate rotor bar and end ring resistances and hence the conductor losses math and approximations, skin effect coefficients. Rotor as the name suggests it is a rotating part of an electrical machine, in which current is induced by transformer action from rotating magnetic field. So, a proper unidirectional torque is produced which can develop high starting torque. This work has developed a steadystate and dynamic mathematical model of three phase slip ring induction motors with external impedance.
The rotor will constantly be turning to align its magnetic field with that of the stator field. Pdf design and analysis of drive system with slip ring induction. 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. I have used ns 120fp to find the synchronous speed, being 1500rpm, but i cannot calculate the slip speed without knowing the rated rpm of the motor.
A successful salesman for general electrics motor division once remarked to one of your instructors that, when asked by a customer how a motor. A slip ring induction motor can be started with external resistance added in its rotor circuit. A wound rotor or slip ring motor has a 3phase winding, similar to the stator. An induction 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. This article is devoted to slip ring induction motors. Photograph your local culture, help wikipedia and win. This way slip ring induction motors will be able to produce high torque even as they are starting. 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. The mechanism employed here is to control the speed via a single thyristor acting. What is the working principle of slip ring 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. Slipring motor manufacturer menzel provides shortterm availability and adaptation, applicationspecific requirements and worldwide logistics. By 1911, baileys book the induction motor summarizes modern theory. The induction motor is made up of the stator, or stationary windings, and the rotor.
Slip ring motor 3 with their solid construction and special design in cast iron or steel akh slip ring motors still have a big resonance in numerous industry sectors. Due to the decrease in the inductive reactance, the phase difference between the current and emf induced will be reduced. You should also make a dc measurement of stator winding linetoline resistance using a dmm. In general, the induction motor is cheaper and easier to maintain compared to other alternatives. The rotor of a 4 pole, 50hz slip ring induction motor has a resistance of 5ohm per phase and inductance of 150mh per phase. Speed control of dc series and shunt motors armature and field control, wardleonard control system. Search wegthreephaseinductionmotorsmasterline50019089brochureenglish. May, 2017 with the advent of variablefrequency solidstate power supplies, speed variation can be provided by the more reliable, less expensive squirrelcage motor.
Slip ring induction motor as an extension to the available non slip power recovery mechanisms available for low power srims. Y provides smooth and stepless cutting of resistance in rotor circuit of the motor, reducing starting current and increasing starting torque of slipring induction motor. The value of slip in induction motor is can never be zero. In squirrel cage induction motor scim the rotor is short circuited and contai. Detection of failures on the highvoltage cage induction motor rotor.
However, the rotor construction of the slip ring motor is. But how does external resistance aid in better starting characteristics. Modeling of alternating current motors and reference frame theory. Wound rotor with slip rings the rotating magnetic field the basic idea of an electric motor is to generate two magnetic fields. Generally, induction motor provides low starting torque as compared to d. Torque slip characteristics of induction motor electrical4u. The slip ring induction motor could be used for industrial wires where variable speed and high starting torque are prime requirements. To overcome this problem, the slip ring induction motor comes into the picture. A 3 phase induction motor can be used for different applications with various speed and load requirements. Abb induction motors for the mining industry english pdf leaflet application note. A photograph of a wound rotor for an induction machine is shown in fig. In this example, the slip rings have a brushlifting device and a sliding contact bar, allowing the sliprings to be shortcircuited when no longer required.
Dec 19, 2017 in this video you will learn connection of slip ring motor with starter panel now you can join our whatsapp group. Read here to know about the starting arrangement and the role played by the external resistances in obtaining better starting characteristics. Before discussing the theory of operation for the induction motor a very basic. Slip ring induction motors are usually started by connecting starting resistance in the secondary circuit, which are shorted out as the motor speed up. Why slip ring induction motor is preferred for high starting torque application. The slip is defined as the ratio of difference of synchronous speed and actual rotor speed to the synchronous speed of the. Search wegthreephaseinductionmotorsmasterline50019089. In the case of a squirrel cage induction motor, the rotor is inaccessible and rotor circuit. Woundrotor motors can be started with low inrush current, by inserting high resistance.
Makwana and others published three phase slip ring induction motor drive with slip power control analysis for different. Speed control of wound rotor induction motor using rotor. Therefore slip ring induction motors are generally employed where load requires high starting torque or good speed control. Slip ring induction motor application slip ring induction motor provides high starting torque. The slip ring induction motor consists of two main parts. The basic idea of an electric motor is to generate two magnetic fields. An induction motor is based on the principle of induction of voltages and currents.
Harley and yao duan georgia institute of technology november, 2009. Wound rotor induction motors with three rotor slip rings have been used in adjustable speed drives for many years. Its operation is based on the principle that when a current carrying conductor is placed in a. In the rotor resistance control method, the slip power in the rotor circuit is wasted as i 2 r losses during the lowspeed operation. 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 sliprings. The value of slip in induction motor at full load varies from about 6% for small motors to about 2% for large motors. The function of a threephase slip ring induction motor is shown in the figure below. Sketch of a crosssection of slip rings for an electric motor.
The first category is the technical analysis, which is based on engineering considerations that evaluate the merits of either a synchronous or a slipring induction motor installation. Slip ring induction motor fundamentals pnpntransistor. Three phase slip ring induction motor a wound rotor or slip ring motor has a 3phase winding, similar to the stator winding. Why slip ring induction motor is preferred for high. Write the classification of 3phase induction motor. Slip ring induction motor have big advantage of having high starting torque compared to squirrel cage motor. Synchronous and slipring induction motors drive cement. Starting of slip ring induction motor explained in an easy. Slip ring motor manufacturer menzel provides shortterm availability and adaptation, applicationspecific requirements and worldwide logistics. Learn more about the construction and operation of a slip ring induction motor. Slip ring induction motor advantages disadvantages and. Rotor induction motor an overview sciencedirect topics.
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