Handbook, textbook, user guide pdf files on the internet quickly and easily. Carbon brush performance on slip rings mining electrical. A modified rotor chopper for speed control of slip ring induction motors s. From the equation 1 it is clear that the motor speed can be changed by a change in frequency f, a number of poles p, and slip s. Terms used in wound rotor slip the difference between a motors synchronous speed and its speed at full load. Jan 09, 2017 speed control by varying rotor resistance. Slip ring induction motor working principle electrical. 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. Featuring a rugged design, these machines provide the unique ability to gradually bring up to speed highinertia equipment and large loads smoothly and easily. A slip ring, three phase induction motor rotates at a speed of 1440rpm, when a supply of 400v, 50hz is applied across the stator terminals. It is very commonly used in industries because it is very cheap, robust, efficient, and reliable. The change in speed depends upon both rotor circuit resistance and load. Sometimes 2 additional for shunt field terminals cabinet type and position dc field supply required.
Modeling and analysis of slip power recovery controlled. Induction motor seminar ppt, pdf report study mafia. The slipring motor 1 the liquid resistance starter 2 demanding applications 2 conclusion 3 technical news issue please circulate to liquid resistance starter developments the ac cage induction to the motor or the charthe slipring motor is the mainstay of acteristics of the motor. In the rotor resistance control method, the slip power in the rotor circuit is wasted as i 2 r losses during the low speed operation.
What are the specific applications of squirrel cage and. Whats the difference between asynchronous and synchronous. There are different methods of starting of 3phase slipring induction motor. In this way, the slip power of main motor is fed to the auxiliary induction motor at a frequency of f. This is because the squirrel cage motor has a simple and rugged construction. The slip ring rotor chamber has two modification openings. Dec 17, 2019 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. Wh en the igbt chopper is on, the resistance is shortcircuited and the curren t id is passed through. Simulation model closed a slip ring induction motor of 500 kw, 2.
The first two contactors are used to change the phase sequence of power supply tochange the direction of a motor as per our requirement. Adjusting the resistance allows control of the speed torque characteristic of the motor. In the same way, the synchronous speed of the differentially cascaded motor can be given by the expression. These motors are having the difference in rotor construction. Generally, it is known as the asynchronous motor because its running speed is less than its synchronous speed. No name of the apparatus type range quantity 1 ammeter mi 010a 1 2 voltmeter mi 0600v 1 3 rotor resistance starter 1. Slip energy recovery of an induction motor slip energy recovery is one of the methods of controlling the speed of an induction motor.
The rotor winding terminals are connected to three slip rings which turn with the rotor. Speed of an induction motor the magnetic field created in the stator rotates at a synchronous speed n s. Slip ring motors electrical calculations and induction. Explain the cascade operation of induction motors to obtain variable speed. Slip in electrical induction motors engineering toolbox. Read here to know exclusively about the speed control of slip ring induction motors by external resistance method and cascade or tandem operation technique. Speed control of induction motor 7 ways to control. Almost 90% of induction motors are squirrel cage motors.
Polyphase induction motors are mainly of two types by construction, squirrel cage and woundrotorwith sliprings. The slip ring or wound rotor motor is an induction machine where the rotor comprises a set of coils that are terminated in sliprings to which external impedances can be connected. The principle of working of squirrel cage and slip ring induction motor is based on faradays law of electromagnetic induction. The resistors for these manual drum controls are a little tricky to size. In slip ring induction motors, the shape of the torque speed curve can be changed by introducing extra resistance into the rotor of the motor. The slip ringsbrushes allow external resistors to be connected in series with the winding. Slip energy recovery of an induction motor circuit globe.
Apr 18, 20 starting and speed control of 3phase slip ring induction motor using plc. Wound rotor induction motor applications how it works wound rotor motors are an extremely versatile breed of induction motors. Number of poles, frequencies and synchronous induction motor speed. Free download induction motor seminar ppt, pdf report. 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. An843, speed control of 3phase induction motor using.
Feb 20, 2014 terms used in wound rotor slip the difference between a motor s synchronous speed and its speed at full load. Slip power recovery system for variable speed operation of. The stator construction is the same in both motors. There are different methods of starting of 3phase slip ring induction motor. A secondary use of the slip ring motor, is to provide a means of speed control. Speed control of induction motor 7 ways to control induction. The torque of the induction motor depends on the rotor resistance. Speed control of 3phase induction motor using pic18 microcontrollers. Pole changing method speed control of induction motor.
There is no difference between squirrel cage and slip ring motors. Therefore the efficiency of three phase induction motor is reduced by this method of speed control. Slip rings a conductive device attached to the end of a wound rotor that conducts current to the brushes. A wound rotor or slip ring motor has a 3phase winding, similar to. Speed control of wound rotor induction motor using rotor.
Parameters of this motor are overshoot andgiven below. The rotor resistance and stand still reactance per phase are 0. Stator winding can be either star or delta connected depending upon the design. The different methods of speed control of induction motor can be broadly classified in to scalar and vector control methods. It is based on freescales 56f800e microcontrollers. Pdf speed control of induction motor using a modified chopper. Although various induction motor control techniques are in practice today, the. This method depends on having a huge starting torque and a small starting current and slip. Almost 90% of induction motors have squirrel cage rotors.
This work has developed a steadystate and dynamic mathematical model of three phase slip ring induction motors with external impedance. This method is also known as static scherbius drive. Why we need to start induction motor using a starter or with one of starting methods. 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. We can react very quickly due to a comprehensive stock of slip ring motors in a power range up to 15000 kw.
Starting of 3 phase induction motors, high starting torque motors, speed control, rheostatic method, pole changing method, cascade control of speed, double cage induction motor, cogging an d crawling of induction motor, induction generator. Slip power recovery systems when are wound rotor motors used. Introduction this application note describes the design of a 3phase ac induction motor drive with volts per hertz control in closedloop vhz cl. The speed control is achieved through slip power recovery with the aid of static power devices. For a slip s, the rotor speed of induction motor n s 1s therefore speed of induction motor can be varied by pole changing.
As induction motors are widely being used, their speed control may be required in many applications. An 8 pole, 50 hz slip ring induction motor runs at a slip of 2. Speed control of three phase induction motor electrical4u. 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.
The stator is the same as is used with a standard squirrel cage motor. As we know the speed of induction motor, torque of induction motor, so, the speed of induction motor can be changed by changing synchronous speed or by changing the slip of induction motor and then parameter r2 and x2 are changed then torque remain constant and change in slip is affected in speed control. Speed control of wound rotor induction motor using rotor resistance control aim. 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. In my previous article, we have seen about the slip ring induction motor construction and its starting methods. Speed control of induction motor using cycloconverter. This article is devoted to slip ring induction motors. All slip rings are connected with variable resistance.
Because of its overall length, a complete source file list. Pdf design and analysis of drive system with slip ring. By introducing external resistance in the rotor circuit, the speed of the motor can be reduced. After understanding the basic principle of operation, it is always easier to understand the speed control of slip ring induction motors. Percent slip is a way to measure the speed performance of an induction motor.
Squirrel cage motor almost 90% of induction motors are squirrel cage motors. Differential equations are solved using computer simulation. The remaining two contactors are used to control the speed of a motor by cutting the resistance of rotor of a motor. Speed control of induction motor detailed explanation.
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. Speed of a dc shunt motor can be varied very easily with good efficiency, but in case of induction motors, speed reduction is accompanied by a corresponding loss of efficiency and poor power factor. Since the number of pole pairs can only be changed in steps like from 2 to 4, this scheme provides stepped speed control. The slip ring motor has very little application in industries. Pdf rotor side control of high power slip ring induction motor. It has susceptibility to speed control by regulating rotor 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. Fullload slip varies from less than 1 % in high hp motors to more than 56 % in minor hp motors. The mechanism employed here is to control the speed. Know how to control the speed of slip ring motors bright. Pdf a simple method of speed control of a three phase slip ring induction motor is accomplished by adding external variable resistance in the rotor. It may be noted that, when the resistance configuration is not the same as that of the rotor, it must. This system cordinates with the motor during the motor startup and makes it available for process control. What external resistance per phase must be added in the rotor circuit so that the motor now runs ate a slip of 17.
Slip ring induction motors are usually started by connecting starting resistance in the secondary circuit, which are shorted out as the motor speed up. It can control the speed of an induction motor over a range from as little as 5% of base speed up to about twice base speed. The slip ring induction motor could be used for industrial wires where variable speed and high starting torque are prime requirements. Cr this pap er presents the analysisand design of all improvised rotor chopper circuit, which can be used to cont rol the speed of slip ring induction motors. Squirrel cage motors have a rotor with short circuited bars whereas slipring motors have wound rotors having three windings each connected in star. Starting and speed control of 3phase slipring induction. 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. Explain the rotor rheostat control of 3 phase slip ring. Different speed control methods of induction motor are explained below. Experimental results are given and compared with the analytical results.
A properly designed variable frequency inductionmotor drive can be very flexible. In this project we are going to start and control the speed of 3phase slip ring induction motor. A modified rotor chopper for speed control of slip ring. That permits control of the current induced in the armatures, giving variable control of the motor output. Know about the parameters which are altered to control the speed in slip ring induction motors. To control the speed control of 3 phase slip ring induction motor by rotor resistance control. Woundrotor motors can be started with low inrush current, by inserting high resistance into the rotor circuit. This slip speed depends upon the mechanical load on the motor shaft. A closedloop speed control scheme for a slip ring induction motor is described in this paper. The speed of a threephase induction motor driving a given load is determined by matching the torque speed characteristics of the motor and load, as shown in fig. By using variable frequency control, it is possible to adjust the speed of the motor either above or below base speed. Whereas in squirrel cage motor, it is not possible to add any external circuit because the bar of the motor is permanently slotted at the end of the ring. Whats the difference between asynchronous and synchronous motors. Speed control of an induction motor there is a various method of speed control of an induction motor.
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. In the present work, the simulation of speed control of motor at different. Speed control of 3phase induction motor microchip technology. Oct 04, 2017 3 phase motor with resistance type starter. An induction motor is practically a constant speed motor, that means, for the entire loading range, change in speed of the motor is quite small. The synchronous motor rotor also has a squirrelcage winding, known as. Wound rotor tecowestinghouse motor company, a world. This slip power loss can be recovered and supplied back to improve the overall. Pdf three phase slip ring induction motor drive with. But slip ring induction motors over come it by having different speed control methods.
The rotor speed of an induction motor is given by the equation shown below. Slip ring induction motor fundamentals pnpntransistor. 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. The regenerative or feedback power converter is controlled to modulate the amount of power put back into the power system, allowing control of the motor speed. Slip ring induction motor working principle electrical mastar. Because the torque curve of the motor is effectively modified by the resistance. Package solution for slip ring induction motor with variable speed control sprs is part of the complete package for motor starting process. The wound rotor induction motor or slip ring motor is widely used for applications requiring speed control or low. One of the major difference between the slip ring and the squirrel cage motor is that the slip ring motor has an external resistance circuit for controlling the speed of the motor. An843, speed control of 3phase induction motor using pic18 mcus.
General purpose slipring induction motors product catalogue. A three phase, 50 hz, 4 pole slip ring induction motor has a star connected rotor. Refer to appendix c for glossary of technical terms. Methods of speed control of induction motor electrical. 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. Three phase slip ring induction motor my tech info. The rotor resistance per phase of the winding is 0. Explain briefly the various speed control schemes of induction motors.
This means that the state of the carbon brushes and the slip ring rotor can be monitored, and cleaning can take place. Slip ring induction motor speed control using a thyristor. A 3 phase induction motor can be used for different applications with various speed and load requirements. Slip ring motor characteristics a slip ring motor or a phase wound motor is an induction motor. Design and analysis of drive system with slip ring induction motor for electric traction. Slip ring induction motor as an extension to the available non slip power recovery mechanisms available for low power srims. Slip ring motor fundamentals bright hub engineering. In previous articles i have discussed the construction, operation, starting, speed control, and classes of squirrel cage induction motors. Jul 07, 2018 speed control of slip ring induction motor is done by external resistance connected in the rotor side. 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. As the speed of the motor reaches its operating speed, rotor winding will be automatically shortcircuited and external resistance will be cut. The slip ring motor the motor has only one motor is the major moving part and if example of an induction the induction motor can designed and used motor which can offer be shown to have a. Learn more about the construction and operation of a slip ring induction motor.
Speed control of slip ring induction motors part ii. The rotor of the slip ring induction motor is also cylindrical or constructed of lamination. When a motor starts to rotate the slip is 100 % and the motor current is at maximum. Based on the construction of the rotor, induction motors are broadly classified in two categories. Starting and control of slipring induction motors599 units. Starting and speed control of 3phase slip ring induction. Rotor side control of high power slip ring induction motor. The motor can be started using grid rotor resistor. The role of cycloconverter in speed control of induction motor is to vary the supply frequency which in turn, changes the speed of 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. In this article, we will learn about squirrel cage and slip ring induction motors. The most basic ways to control the speed of a slip ring induction motor is either from the stator or rotor side. This method is applicable to threephase slip ring induction motor only.
The construction of a stator is the same for both the squirrel cage and slip ring induction motor. Squirrel cage motors are normally more efficient than slipring motors, and. By adding external resistance to rotor winding starting current will low but it has high starting torque. Pillai department ofelectrical engineering, indian institute of technology, bombay, powai, bombay 400076, india abstra. The open circuit voltage on open circuit between the slip rings 0 volts. Slip ring motor manufacturer menzel provides shortterm availability and adaptation, applicationspecific requirements and worldwide logistics. Put on the dc supply and run the dc motor of a speed close to the synchronous speed of. Pdf the use of squirrel cage motor for traction has revolutionised the motive power of a locomotive. The speed of an ac motor depends on the frequency of the input power and.
Various induction motor speed control methods advantages. 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 operating point is the intersection of the two characteristics and we can fix for a given load and motor parameters. In this article, we will learn about the speed control of slip ring induction motors and will appreciate that the speed control of slip ring motors are so flexible when compared to the squirrel cage induction motors.
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