Oct 10, 2016 a wound rotor induction motor is also known as slip ring induction motor. Woundrotor motors can be started with low inrush current, by inserting high resistance into the rotor circuit. The armature reactance varies from xq to xd periodically. We develop appropriate solution with characteristic lines that match precisely your specifications and demands for your application. Read here to know about the starting arrangement and the role played by the external resistances in obtaining better starting characteristics. Theory polyphase induction motors are mainly of two types by construction, squirrel cage and woundrotorwith slip rings. Moflon has been manufacturing and supplying slip rings and rotary unions to companies, contractors, and other endusers for more than 30 years now. In the slip ring motor, the windings on the rotor are terminated to three insulated slip rings mounted on the shaft with brushes resting on them. The stator construction is the same in both motors. When the stator winding of the slip ring motor is connected to the three phase supply, it produces a rotating magnetic field in the same way as a squirrel cage induction motor. Capacitor start ac induction motor this is a modified splitphase motor with a capacitor in series with the start winding to provide a start boost.
The slip ring induction motor has two distinctly separate parts, one is the stator and other is the rotor. 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. 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. 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. Reveal answer the difference between the speed of the rotating magnetic field fixed by line power frequency and the speed of the rotor is called slip speed. Motor slip the rotor in an induction motor can not turn at the synchronous speed. In the case of a squirrel cage induction motor, the rotor is inaccessible and rotor circuit resistance is xed, whereas the woundrotor machines are provided with slip rings.
Slip ring motor fundamentals brighthub engineering. A slip ring induction motor can be started with external resistance added in its rotor circuit. If the ohmic values of these resistances are properly chosen and if the resistors are designed for. Pdf design and analysis of drive system with slip ring. For each type of motor there are many different mounting arrangements, for example. Fault identification of 3phase slip ring induction motor. When a 3 phase supply is given to the stator winding it sets up a rotating magnetic field in space. But how does external resistance aid in better starting characteristics.
In the case of a squirrel cage induction motor, the rotor resistance is very low so that the current in the rotor is high, which makes its starting torque poor. Like the splitphase motor, the capacitor start motor. This rotor is made up from parallel aluminum or copper bars. Ysalient features y robust and nonflammable construction.
Fault identification of 3phase slip ring induction motor free download as powerpoint presentation. Pdf design and analysis of drive system with slip ring induction. Slip ring induction motor application, construction, working principle, advantages and disadvantages, speed control of slip ring induction motor, the difference between slip ring i. Laboratory instruction manual jis college of engineering. The external resistor can be used to boost the starting torque of the motor and change the speedtorque. In the simplest form of a woundrotor motor, the rotors electromagnet coil terminates on a pair of slip rings which permit contact with. This rotating magnetic field has a speed which is known as the synchronous speed this rotating magnetic field induces the voltage in rotor bars and hence shortcircuit currents start flowing in the rotor bars. 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. Slip ring motor manufacturer menzel provides shortterm availability and adaptation, applicationspecific requirements and worldwide logistics. In the case of a squirrel cage induction motor, the rotor is inaccessible and rotor circuit. I will tell you about the construction of wound rotor induction motor in the first section. The rotor winding terminals are connected to three slip rings which turn with the rotor.
The stator consists of 3ph winding forms wound poles that carry the supply current to induce a. Y designed to give equal resistance in each phase with special profile of fixed and moving electrodes. The slip ring induction motor working in the induction principle. Learn more about the construction and operation of a slip ring induction motor. By far the most commonly used ac motor is the induction motor. Sep 18, 2018 induction motors have been ruling the industrial world for many decades. Squirrel cage rotor wound type rotor or slip ring type rotor squirrel cage rotor in this type 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. Slip ring induction motor have big advantage of having high starting torque compared to squirrel cage motor. The induction motor is made up of the stator, or stationary windings, and the rotor. Three phase slip ring induction motor my tech info.
Generally we all are know induction motor is most widely used motor in industrial. Speed control of wound rotor induction motor using rotor. Also know about the qualities of slip ring induction motors. This type of rotor is provided with a 3phase, doublelayer, distributed winding consisting of coils used in alternators. This allows an introduction of an external resistor to the rotor winding. A wound rotor or slip ring motor has a 3phase winding, similar to. What makes the wound rotor motor a unique induction machine is its rotor. Wound rotor tecowestinghouse motor company, a world leader. There are two types of induction motors, one with wound type rotor, also called slip ring motor and another one with squirrelcage rotor. Y available in various sizes for motors upto 5000 kw. Wound rotor induction motors ac motors electronics. Rheostat starting can only be used with slip ring motors. 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. A stator is in all the motor only winding on the stator is vary with types of motor.
It also requires meticulous and periodic maintenance of the brushes, brush gear, sliprings, external rotor resistances etc. Avoid using this type of motor in any applications requiring high onoff cycle rates or high torque. Wound rotor induction motors ac motors electronics textbook. 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. As a leading designer and manufacturer of slip rings, our solutions are applicable even in demanding applications. The results of the theoretical analysis of transient currents and electromagnetic torque at the. Slip ring induction motors are usually started by connecting starting resistance in the secondary circuit, which are shorted out as the motor speed up. On these motors, the resistance of the rotor circuits can be increased with an external resistor. A wound rotor induction motor is also known as slip ring induction motor. The potential across resistor r will cause a current to flow from y to x through the resistor.
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. It is very commonly used in industries because it is very cheap, robust, efficient, and reliable. Three notable applications have been helicopter rotor deicing slip rings, radar pedestal slip rings, and wind turbine slip rings. The slip ring induction motor could be used for industrial wires where variable speed and high starting torque are prime requirements. The rotor windings are similar to those found on a dc armature, with the coils connected together to a set of rings. Higher maintenance of brushes and slip rings compared to squirrel cage motor. Slip ring induction motor working principle electrical mastar. Pdf three phase slip ring induction motor drive with.
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. One slip ring is attached to each end of the rotating loop. 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. C series motors but this disadvantages of the induction motor can be overcome by slip ring induction motor. What is the working principle of slip ring induction motor. Based on the construction of the rotor, induction motors are broadly classified in two categories. Each of these applications requires long life, high conductivity for high power transfer, and operation in very difficult environments. Wound rotor with slip rings the rotating magnetic field the basic idea of an electric motor is to generate two magnetic fields. According to the execution of brushes and sliprings the motors are classified into two groups.
The rotor of the slip ring motor has a cylindrical core with parallel slots, and each slot consists each bar. This rotating magnetic field has a speed which is known as the synchronous speed. Slip ring induction motor application slip ring induction motor provides high starting torque. Why are there two different designs of rotor construction for induction motors. The construction of a stator is the same for both the squirrel cage and slip ring induction motor. Makwana and others published three phase slip ring induction motor drive with slip power control analysis for different load torque using microsoft excel as software. Y requires minimum initial investment and negligible maintenance. A squirrel cage motor is thus preferred to a slipring motor. The theory used in the work was collected by studying literature on how electrical motors work, and by simplifying the explanations to suit the intended reader. However, it reduces substantially in a slip ring motor due to the high impedance of the rotor circuit. Wound rotor induction motors chapter ac motors pdf version.
Squirrel cage rotor wound type rotor or slip ring type rotor squirrel cage rotor in this type. The stator is the outer component of the motor which can be seen. To prevent oil vapor ingress into the motor enclosure, the inner side of bearing endshield is provided with additional motor seal. The rotor will constantly be turning to align its magnetic field with that of the stator field. The main difference between slip ring and squirrel cage induction motor is the rotor construction.
Fieldharmonic theory of slip ring motor taking multiple armature reaction into account article pdf available in proceedings of the institution of electrical engineers 1178. High reliability slip ring design for wind turbines. 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. Slip ring induction motor working principle electrical. A slipring motor also requires a larger space for the motor and its controls. The rotor of the slip ring induction motor is also cylindrical or constructed of lamination.
In general, the induction motor is cheaper and easier to maintain compared to other alternatives. Their sole purpose is to allow resistance to be placed in series with the rotor windings while. The motor whose rotor is wound type such type of motor is called slip ring induction motor, whereas the squirrel cage motor, has a squirrel cage type rotor. A brush, or wiper, slides on a rotating ring and maintains continual electrical contact during rotation figure 1 shows one such ring and brush configuration. Slip ring induction motor is made up from wound rotor and squirrel cage induction motor is made up from the squirrel cage rotor. The slip ring motor has very little application in industries.
So, this motor is used in applications like lifts, pumps, mills where we require high starting torque. This article is devoted to slip ring induction motors. 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. This is the ability to create electrical current in a conductor by moving a magnetic field past the conductor. Adjusting the resistance allows control of the speedtorque characteristic of the motor. Answer anurag pattanayak since in a slip ring induction motor, the rotor resistance is low, this can cause very high current and low starting torque. The basic idea of an electric motor is to generate two magnetic fields. A slip ring can be used in any electromechanical system that requires rotation while transmitting power or signals. The fiber brush design involves the bundling of multiple. So by externally adding resistance, we increase the rotor resistance and thus decrease the starting current and increase the starting. The bearing oil ring maintains lubrication when forcefeed oil supply fails, allowing the motor to come safely to a standstill.
Induction motor theory jerry bednarczyk, pe course content introduction the ac induction motor is well suited to applications requiring constant speed operation. Xd is the synchronous reactance of armature coil offered to the flow of direct axis. It can improve mechanical performance, simplify system operation and eliminate damageprone wires dangling from movable joints. Starting of slip ring induction motor explained in an easy. Wound rotor tecowestinghouse motor company, a world. This will ensure 100% reliability in operation of the locomotive. Three phase slip ring induction motor a wound rotor or slip ring motor has a 3phase winding, similar to the stator winding. In the second section, i would be throwing light on the operation and working principle of wound rotor induction motor. The starting of an induction motor does not relate to simple switching alone.
But in an induction motor only the stator winding is fed with an ac supply. 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. Generators, motors, transformers, and solenoids each use the principle of electromagnetism. Our motors are designed for long life and reliable operation. The rotor of the slip ring induction motor is connected to the external resistances. High reliability slip ring design for wind turbines glenn dorsey moog inc. The catalogue covers slipring induction motors called also wound rotor induction motors that are. What happens if slip rings are short circuited in a 3. This means that the state of the carbon brushes and the slip ring rotor can be monitored, and cleaning can take place. The slip ringsbrushes allow external resistors to be connected in series with the winding. The slip ring induction motors usually have a phasewound rotor. Design and analysis of drive system with slip ring induction motor for electric traction in india article pdf available in international journal of power electronics and drive systems 53.
There is no difference between squirrel cage and slip ring motors. We saw the construction of the squirrel cage induction motor. Explain what slip speed is for an ac induction motor, and why there must be such as thing as slip in order for an induction motor to generate torque. Starting of slip ring induction motor explained in an easy manner. 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 rotor core is made up of steel laminations which have slots to accommodate formed 3single phase windings. The slip ring rotor chamber has two modification openings. Generally, induction motor provides low starting torque as compared to d. Wound rotor induction motor the engineering projects. The stator circuit is rated as same in the squirrel cage motor, but the rotor is rated in frame voltage or short circuit current. The concept of the rotating magnetic field is central to ac motor theory, so it is imperative that students grasp this concept before moving on to more advanced concepts. An engineering guide to soft starters control techniques. The construction of the slipring induction motor is exactly similar to the construction of squirrel cage induction motor. But adding external resistance, as in the case of a slip ring induction motor, makes the rotor resistance high when starting. Apr 11, 2017 induction motors generally will have low starting torque compared to dc series motor. What are the applications of a slipring induction motor. Induction motors have been ruling the industrial world for many decades. An asynchronous motor with wound rotor is used as traction. Induction motor theory jerry bednarczyk, pe course content introduction.
Slip ring induction motor fundamentals pnpntransistor. The slip ring motors in our mebsgr series that are described in the following text are in the ic 411 cooling class, known as surfacecooled or ribbedcooled. Ac induction motors are the most common motors used in industrial motion control systems, as well as in. Almost 90% of induction motors have squirrel cage rotors. If you want to know about the slip ring induction motor. In a dc motor, supply is needed to be given for the stator winding as well as the rotor winding.
A slipring motor is expensive, as are its controls, compared to a squirrel cage motor. A woundrotor motor slip ring motor is a type of induction. Pdf this work has developed a steadystate and dynamic mathematical. We can react very quickly due to a comprehensive stock of slip ring motors in a power range up to 15000 kw. Oct 04, 2017 3 phase motor with resistance type starter. Before discussing the theory of operation for the induction motor a very basic concept, that of a rotating field, must be understood. This final thesis will mostly be dedicated to induction motors but also to synchronous permanent magnet and reluctance motors. Jul 25, 2019 squirrel cage induction motor working principle. Instead of a series of rotor bars, a set of insulated rotor coils is used to accept external impedances. By putting resistance in series with the rotor windings, the starting current can be kept low while mainta. Slip ring motor conversion to vsd driven standard squirrel. Portland slip ring induction motorsbrush holder problems and. A slip ring is an electromechanical device that allows the transmission of power and electrical signals from a stationary to a rotating structure.
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