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. 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. Slipring induction motor connection and testing youtube. I will tell you about the construction of wound rotor induction motor in the first section. Slip ring motor conversion to vsd driven standard squirrel. Instead of a series of rotor bars, a set of insulated rotor coils is used to accept external impedances. Slip ring induction motor have big advantage of having high starting torque compared to squirrel cage 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. Xd is the synchronous reactance of armature coil offered to the flow of direct axis. Each phase winding is separated by 1200 electrical. Slip of induction motor plays an important role in the operation of the induction 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. So, this motor is used in applications like lifts, pumps, mills where we require high starting torque. This final thesis will mostly be dedicated to induction motors but also to synchronous permanent magnet and reluctance motors. Slipring modular motors from abb, availability for heavy load inertia applications english pdf leaflet technical note.
The singlephase ac induction motor best fits this description. As the name suggests, this type of motor has only one stator winding main winding and operates with a singlephase power supply. Slip ring induction motor application slip ring induction motor provides high starting torque. By far the most commonly used ac motor is the induction motor. Pdf design and analysis of drive system with slip ring. Generally, induction motor provides low starting torque as compared to d.
C series motors but this disadvantages of the induction motor can be overcome by slip ring induction motor. Portland slip ring induction motorsbrush holder problems. Construction of three phase induction motor electrical4u. Abb induction motors for the mining industry english pdf leaflet. Torque slip characteristics of induction motor electrical4u. Because of its simplicity and cheapness, the 3phase squirrelcage induction motor is now by far the most common type of motor in use for driving industrial plant, particularly of small power ratings up to 20 kw. Speed control of wound rotor induction motor using. The slip power is the air gap power between the stator and the rotor of an induction motor which is not converted into mechanical power. 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. 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.
The bearing oil ring maintains lubrication when forcefeed oil supply fails, allowing the motor to come safely to a standstill. In a dc motor, supply is needed to be given for the stator winding as well as the rotor winding. Dec 01, 2017 slipring induction motor also known as rotor resistance start motor. But how does external resistance aid in better starting characteristics. Theory polyphase induction motors are mainly of two types by construction, squirrel cage and woundrotorwith slip rings.
What are the applications of a slipring induction motor. Slip ring induction motor working principle electrical mastar. Electrical machinesii lab grietelectrical and electronics. State the steps to draw the equivalent circuit of 3phase induction motor. 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. What makes the wound rotor motor a unique induction machine is its rotor. Wound rotor induction motor the engineering projects.
This means that the state of the carbon brushes and the slip ring rotor can be monitored, and cleaning can take place. Learn more about the construction and operation of a slip ring induction motor. The rotor will constantly be turning to align its magnetic field with that of the stator field. Stator winding can be either star or delta connected depending upon the design. A stator is in all the motor only winding on the stator is vary with types of motor. In this type of induction motor s, the rotor comes with the separate winding section as similar to stator of the motor. The armature reactance varies from xq to xd periodically. The static kramerdrive converts the slip power of an induction motor into ac power and supply back to the line. Slip in electrical induction motors engineering toolbox. Prabal series squirrel cage slip ring crane duty motors are specially designed for service on cranes and hoists. The slip ring rotor chamber has two modification openings.
Apr 11, 2017 induction motors generally will have low starting torque compared to dc series motor. Woundrotor motors can be started with low inrush current, by inserting high resistance into the rotor circuit. Determine the starting torque as a percentage of fullload torque if fullload slip is 3 per cent. There are two types of induction motors, one with wound type rotor, also called slip ring motor and another one with squirrelcage rotor.
The least expensive and most widely spread induction motor is the socalled squirrel cage motor. The rotor winding terminals are connected to three slip rings which turn with the rotor. The slip is defined as the ratio of difference of synchronous speed and actual rotor speed to the synchronous speed of the. In all singlephase induction motors, the rotor is the squirrel cage type. It consists of plc board which has input and output ports, contactors which are used for either to close or to openthe terminals and one three phase slip ring induction motor. Pdf fieldharmonic theory of slipring motor taking multiple. Speed control of three phase induction motor electrical4u. A wound rotor induction motor is also known as slip ring induction motor. 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. Starting and speed control of 3phase slipring induction. Portland slip ring induction motorsbrush holder problems and. Slip ring induction motor is made up from wound rotor and squirrel cage induction motor is made up from the squirrel cage rotor. This work has developed a steadystate and dynamic mathematical model of three phase slip ring induction motors with external impedance. The two brushes are connected to a single phase starconnected rheostat as.
Slip ring motor manufacturer menzel provides shortterm availability and adaptation, applicationspecific requirements and worldwide logistics. Crane duty motors, slip ring crane duty motors, squirrel cage. Three phase slip ring induction motor my tech info. The torque produced by the induction motor is directly proportional to induction motor slip. When the speed control of three phase induction motor is done by adding resistance in rotor circuit, some part of power called, the slip power is lost as i 2 r losses. The slip ring motors are used mainly for industrial. Induction motor theory jerry bednarczyk, pe course content introduction the ac induction motor is well suited to applications requiring constant speed operation. 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. The above block diagram shows the controlling of a three phase slip ring induction motor using programmable logic controller. Also appreciate the external resistances and carbon brush arrangements with the slip rings and advantages of slip ring induction motor. 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. Computer simulation and mathematical modelling of static rotor. Feb 25, 2017 depending on type of workload there are various type of starters for a slip ring induction motor.
If the ohmic values of these resistances are properly chosen and if the resistors are designed for. Pdf the voltage equations of the slipring motor including the multiple armature reaction, i. The main motor is necessarily a slip ring induction motor but the auxiliary motor can be slip ring or squirrel cage induction motor. Traditional design of cage rotor induction motors ronald g. The rotor of the slip ring induction motor is also cylindrical or constructed of lamination. What are the type of starter used for slip ring induction motor. The slip ring induction motor was developed a short time later. Induction motors generally will have low starting torque compared to dc series motor.
By putting resistance in series with the rotor windings, the starting current can be kept low while mainta. Read here to know about the starting arrangement and the role played by the external resistances in obtaining better starting characteristics. Speed control of slip ring induction motors part ii. Adjusting the resistance allows control of the speedtorque characteristic of the motor. The construction of the slip ring induction motor is exactly similar to the construction of squirrel cage induction motor. Single phase induction motor, theory of operation double revolving field theory, equivalent circuit, determination of.
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. Abb slipring modular motors abb high voltage induction. Wound rotor with slip rings the rotating magnetic field the basic idea of an electric motor is to generate two magnetic fields. Single phase induction motor, theory of operation double revolving. Before discussing the theory of operation for the induction motor a very basic. This work has developed a steadystate and dynamic mathematical model of three phase slipring induction motors with external impedance.
Y designed to give equal resistance in each phase with special profile of fixed and moving electrodes. Different types of starters for three phase induction motors, its necessity, basic contactor. Advantages and disadvantages of slip ring induction motor. In this example, the slip rings have a brushlifting device and a sliding contact bar, allowing the slip rings to be shortcircuited when no longer required. This article is devoted to slip ring induction motors. Slip power recovery system for variable speed operation of. Noload and blocked rotor test on an induction machine aim to estimate magnetization and leakage impedance parameters of induction machine using noload and blocked rotor tests theory an induction machine in its equivalent circuit form is akin to a transformer with slip as an additional parameter. When a motor starts to rotate the slip is 100 % and the motor current is at maximum.
But in an induction motor only the stator winding is fed with an ac supply. In general, the induction motor is cheaper and easier to maintain compared to other alternatives. To prevent oil vapor ingress into the motor enclosure, the inner side of bearing endshield is provided with additional motor seal. A wound rotor or slip ring motor has a 3phase winding, similar to the stator.
The 3phase set of currents, each of equal magnitude and with a phase. Y requires minimum initial investment and negligible maintenance. The value of slip in induction motor at full load varies from about 6% for small motors to about 2% for large motors. The induction motor is made up of the stator, or stationary windings, and the rotor. Resistance starter for 3phase, slipring induction motor. 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. Starters limit the starting current in an induction motor which goes 56 times of full load current as slip remains 1. Slip and motor current are reduced when the rotor begin turning. The potential across resistor r will cause a current to flow from y to x through the resistor.
The fieldharmonic theory of a synchronous induction machine. 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 however, no power is applied to the slip rings. 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. The shortcircuit current of a small 3phase induction motor is 3 times the fullload currents. In the second section, i would be throwing light on the operation and working principle of wound rotor induction motor. Slip ring induction motor fundamentals pnpntransistor.
Traditionally, speed control of slip ring induction motor was achieved. Squirrel cage rotor wound type rotor or slip ring type rotor squirrel cage rotor in this type. Do you know what happens to slip ring motor when external resistance is added. 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. Speed control of wound rotor induction motor using rotor. Foundation design for high voltage induction motors english pdf leaflet product note. These motors can serve as auxiliary motors in rolling mills or wherever intermittent duty drives are required. Like most motors, an ac induction motor has a fixed outer portion. Wound rotor induction motors ac motors electronics. Differential equations are solved using computer simulation. Starting of slip ring induction motor explained in an easy. Noload and blocked rotor test on an induction machine aim.
Starting of squirrel cage induction motors485 an induction motor can be regarded as a transformer with a small air gap in the magnetic circuit. Write the classification of 3phase induction motor. For satisfactory operation, motor a must be phase wound slip ring type with the stator to rotor winding ratio of 1. Select current density in rotor bars and end rings depends on ambient temp, cooling conditions, and duty cycle, and from rotor bar and end ring currents get. Their sole purpose is to allow resistance to be placed in series with. Therefore the efficiency of three phase induction motor is reduced by this method of speed control. A metal ring at the ends resulting in a short circuit connects the wires along the rotor axis. Oct 04, 2017 3 phase motor with resistance type starter. Be specially designed for energy saving purpose which is totally enclosed and fancooled type. Y available in various sizes for motors upto 5000 kw. The slip ring induction motor working in the induction principle. Be careful it can hurt to tangle with a threephase motor.
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. The basic idea of an electric motor is to generate two magnetic fields. Wound rotor tecowestinghouse motor company, a world. What is the working principle of slip ring induction motor. Slipring induction motor also known as rotor resistance start motor. Sketch of a crosssection of slip rings for an electric motor. A 3 phase induction motor can be used for different applications with various speed and load requirements. Inductive reactance depends on the frequency and the slip.
Another type is squirrel cage motor that has no wire winding and has no slip rings. The slip ring induction motor could be used for industrial wires where variable speed and high starting torque are prime requirements. Equivalent circuit of an induction motor enables the performance characteristics which are evaluated for steady state conditions. Ramamoortychopper controlled slip ring induction motor. Slip ring motor fundamentals brighthub engineering. 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 stator is the outer component of the motor which can be seen. There is no difference between squirrel cage and slip ring. Also know about the special constructional features of the rotor. But there is no restriction for the direction of phase rotation. Polyphase induction motors are mainly of two types by construction. 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. This is similar to a transformer, whose secondary is rotating and shortcircuited.
Why we need to start induction motor using a starter or with one of starting methods. What is slip ring induction motor practical explanation. Type of induction motor for ac in which the rotor has wire winding. A slip ring is an electromechanical device that allows the transmission of power and electrical signals from a stationary to a rotating structure. We can react very quickly due to a comprehensive stock of slip ring motors in a power range up to 15000 kw. A slip ring induction motor can be started with external resistance added in its rotor circuit. A typical asynchronous motor is shown in figure 71. Pdf three phase slip ring induction motor drive with. The rotor windings are similar to those found on a dc armature, with the coils connected together to a set of rings. State the condition for maximum torque of 3phase induction motor. The difference is that, in the case of the induction motor, the secondary windings can move due to the rotation of the rotor the secondary winding of the im, the induced voltage in it does not have the same frequency of the stator the primary voltage 3192014 emdii induction motor design. Starting of slip ring induction motor explained in an easy manner. The slip ring motor has very little application in industries.
Slip ring induction motors are usually started by connecting starting resistance in the secondary circuit, which are shorted out as the motor speed up. One of the main classifications of asynchronous motors are the slip ring induction motors. An induction motor is based on the principle of induction of voltages and currents. In the case of a squirrel cage induction motor, the rotor is inaccessible and rotor circuit. Nov 27, 2019 the three phase induction motor is the most widely used electrical motor. The slip ring induction motor consists of two main parts. The voltage and current is induced in the rotor circuit from the stator circuit for the operation. Harley and yao duan georgia institute of technology november, 2009. The slip rings brushes allow external resistors to be connected in series with the winding.
When the injected voltage is in phase opposition with the induced rotor e. It is very commonly used in industries because it is very cheap, robust, efficient, and reliable. An887, ac induction motor fundamentals microchip technology. The construction of a stator is the same for both the squirrel cage and slip ring induction motor. Slip power recovery system for variable speed operation of slip ring induction motor. Therefore slip ring induction motors are generally employed where load requires high starting torque or good speed control. Pdf this work has developed a steadystate and dynamic mathematical model of three phase slipring induction motors with external impedance find, read. Also know about the qualities of slip ring induction motors. A slip ring can be used in any electromechanical system that requires rotation while transmitting power or signals. This can be used in starting a slipring induction motor, for example. Induction motors an induction motor has two magnetically coupled circuits. The slipring motor or woundrotor motor is a variation. Ysalient features y robust and nonflammable construction. They can also be used for similar applications such as material handling equipments, and cranes of all types.
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