Slip ring rotor or wound rotor or phase wound rotor. It is shown that some of these harmonics cannot induce. Each pole has a neck and a pole shoe forming a continuous pole arc facing the rotor. Foundation design for high voltage induction motors english pdf leaflet product note. By far the most commonly used ac motor is the induction 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. We are committed to becoming the preferred source for electric motors and controls with the highest standard of quality service and support. Pdf matlab examples design of wound rotor induction. The induction motor was attractive as it was familiar to the product department, potentially lowest in cost and could be readily operated without requiring a rotor position or speed sensor. Pdf induction motor with outer rotor and ring stator. Another type is squirrel cage motor that has no wire winding and has no slip rings. The construction of stator of the induction motor is almost the same as other motors. Induction motor with outer rotor and ring stator winding for multispeed applications article pdf available in ieee transactions on energy conversion 284.
You said this was a wound rotor induction motor, not a synchronous motor. With indian and international standards almost similar for the induction motors, squirrel cage or wound rotor, the replacement is extremely easy and fast reducing downtime of outage, which is vital for sustaining. The slip ring of the wound rotor induction motor has bad contact. The rotor of the slip ring motor has a cylindrical core with parallel slots, and each slot consists each bar. Jan 28, 2015 very interesting question i am glad someone asked it on quora. Novel highspeed induction motor for a commercial centrifugal. Induction motor output, losses and efficiency the various losses in the stator of three phase induction motor are stator copper losses and stator iron losses. The wound rotor motor is particularly effective in applications where using a squirrelcage motor may result in a starting current thats. Slip ring induction motor fundamentals pnpntransistor. Selection of induction motors for industrial applications.
Wound rotor motors can be started with low inrush current, by inserting high resistance into the rotor circuit. F and reactance under running conditions condition for maximum torque under running conditions. Current signature analysis csa is used to accurately measure faults in the induction motor rotors through changes in the rotor magnetic field. It consists of a cylinder of steel laminations, with aluminum or copper conductors embedded in its surface. R loss, including brushcontact losses for woundrotor machines, shall be determined from the. It also provides a way to recover the power generated by the increased slip by converting the slip energy to. Historically, it has been used for hardtostart, high inertia fans, or where power system requirements demand a soft start. Various techniques have been developed for broken rotor bar fault diagnosis. Instead the rotor is wound with shorted turns in which the environmental field induces a current. Pdf seriesconnected induction motor has the ability of operation either at two speeds. Type of induction motor for ac in which the rotor has wire winding.
Wound rotor induction motors ac motors electronics. Unbalanced stator winding power supply voltages will induce negative sequence voltages and currents in the rotor winding. This curve is called the torquespeed characteristic curve. Other articles where woundrotor induction motor is discussed. 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. 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.
A wound rotor induction motor may also act as a generator when driven above the synchronous speed. In contrast, a traditional induction motor aka squirrel cage motor has windings that are permanently shortcircuited by an end ring. 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 wound rotor with sliprings. That current in turn produces a field that interacts with the environment to drive the rotor. The ratio of the diameter of the motor to the width of the stator core measured across the. Electric motor construction of induction motors britannica. How can a variable rotor resistance be produced to combine the. Since there are connections to both the stator and rotor, such a machine is known as a doublyfed induction generator dfig. Speed control of wound rotor induction motor using rotor. The works of the stator is common in all motor to develop a magnetic field. Almost 90 percentage of induction motors are squirrelcage type, because this type of rotor has the simplest and most rugged construction imaginable and is almost.
Ieee std 1122004, ieee standard test procedure for polyphase. Modelling the induction machine the machine was modelled through the use of an equivalent circuit. The wound rotor induction motor has some distinct application advantages. The stationary part of the motor is called stator and rotary part of the motor is called rotor. Wound rotor induction motors ac motors electronics textbook. A wound rotor induction motor has a stator like the squirrel cage induction motor, but a rotor with insulated windings brought out via slip rings and brushes. Pdf the proposed method is used to predict the efficiency and power factor. Squirrel cage induction motor an overview sciencedirect topics. Motors employing this type of rotor are widely known as phase wound motors or wound motor or slipring motors. 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.
Lamination is necessary since a voltage is induced along the axial length of the steel as well as in the stator conductors. Squirrel cage rotor wound type rotor or slip ring type rotor squirrel cage rotor in this type. This article will highlight the important concepts for wound rotor motors that must be understood before purchasing one of these but know it is not allinclusive. It also defines the running thermal capability, thermal limit curve, accelerating thermal limit and locked rotor thermal. No comparable standard exits for wound rotor induction or synchronous motors. In this paper the speed control problem for a wound rotor induction motor is considered. A wound rotor induction motor is also known as slip ring induction motor. The speed of induction motor can be varied by changing supply voltage. A squirrelcage rotor is the rotating part of the common squirrelcage induction motor. The induction motors are simple and of rugged design, low maintenance, low cost and most suitable means for such applications. The speed is controlled by changing the external resistance in the rotor circuit. Jul 17, 2017 the stator of a wound rotor motor is the same as a typical induction motor, but the rotor has a threephase winding, with each of the winding terminals connected to separate slip rings.
There are two types of induction motors, one with wound type rotor, also called slipring motor and another one with squirrelcage rotor. The stator iron losses consist of eddy current loss and hysteresis loss. How to test three phase ac motors learning electrical. In a wound rotor induction motor or generator, there is a transformer coupling effect between the stator and rotor windings. Each phase to phase must have a continuity if winding is ok. A 460 v, 25hp, 60hz, fourpole, yconnected wound rotor induction motor has the following impedances in ohms per phase referred to the stator circuit. Diagnostics of rotor and stator problems in industrial. The basic idea of an electric motor is to generate two magnetic fields. This type of 3phase induction motor has high starting torque, which makes it ideal for applications where standard nema design motors fall short.
One of the most commonly seen motor faults is the broken rotor bar, which can cause serious motor damage if not detected in time 3, 4. Slip ring induction motor is also known as wound rotor induction motor. Figure 1 showed a plot of induction motor torque vs speed from zero to synchronous speed. Diagnostics of rotor and stator problems in industrial induction motors by fang duan b. The reason why the rotor of an induction motor is set into rotation is as follow.
You should also make a dc measurement of stator winding linetoline resistance using a dmm. Jan 09, 2017 this method is applicable to squirrel cage induction motor only. Global induction motors market analysis, trends, share. The rotor windings are usually of a threephase type with three connections made to insulated conducting rings known as slip rings mounted on. Adjustable speed drives, motor dynamics, stability, woundrotor induction. 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. Abbs general purpose motors combine quality, costefficiency and industry experience with short lead times. The 3phase set of currents, each of equal magnitude and with a phase. What is the advantage and disadvantage of rotor resistance. 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.
Their sole purpose is to allow resistance to be placed in series with the. Various induction motor speed control methods advantages. Construction of induction motor the three phase induction motor is a preferable type of motor. Ir value will be usually high several hundred megaohms for a dry insulation system.
A plant process is shut down for maintenance once every two years. Squirrel cage induction motor is used in lathes, drilling machine, fan, blower printing machines etc. The function of data acquisition is sampling and amplifying the physical signal data. Their sole purpose is to allow resistance to be placed in series with the rotor windings while. The rotor of the three phase induction motor are further classified as. Introduction to induction motor the engineering projects. Woundrotor induction motor the magnetizing branch can not be neglected i0 may be 40% of ip due to the air gap for motors greater than 2 hp, the magnetization branch can be shifted to the input terminals for a motor running at a slip s, the rotor speed is ns1s this will modify the values of e1, i1, e2 and i2. Speed control of an induction motor is possible by having a resonant rotor circuit, which is adjusted according to the slip frequency. In recent advancements in electric machine and drives, wound rotor motor is extensively used. The induction motor is manufactured without any electrical connections to the rotors. Adjusting the resistance allows control of the speedtorque characteristic of the motor. Control of motor characteristics by squirrelcage rotor design. What is the rule to determine the rotor current in an.
The rotor will constantly be turning to align its magnetic field with that of the stator field. Modify the surface of the slip ring and regulate the pressure of the carbon brush. The merit of using wound rotor induction motor is to control speedtorque characteristics by inserting external resistance. A new soft starting method for woundrotor induction motor article pdf available in journal of electrical engineering 621 january 2011 with 1,969 reads how we measure reads. A squirrelcage induction motor is one in which the secondary circuit consists of a. Theseindividualrotormagneticfieldsproducea combine. Nov 27, 2019 the three phase induction motor is the most widely used electrical motor. Wound rotor induction motors chapter ac motors pdf version. Development of a high speed solid rotor asynchronous drive. The stator core has at least two poles with the stator windings wound thereon and a yoke connecting the poles.
The threephase induction motor is the easiest motor of this type to understand so these notes start with that type. Why the revolving speed of the induction motor is lower than the rated value. For a typical induction motor, pullout torque is 200 to 250 % of rated fullload torque and starting torque at zero speed is about 150% of fullload torque. Pdf a new soft starting method for woundrotor induction motor. 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. With this kind ofrotor a higher useful section for flux circulation is obtained, but one of the drawbacks ofthis motor is the fact that the lines ofmagnetic. 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. When suitable automatic data acquisition systems or highspeed. Oct 12, 2017 rotor current rotor current can be calculated by comparing the ampcond on stator and rotor 20. Some special induction motors are constructed with insulated coils in the rotor similar to those in the stator winding. But the rotor construction differs with respect to the type of motor. Insulation resistance or ir test is carried out by maintenance engineers to ensure the healthiness of the overall insulation system of electrical equipment it reflects the presence or absence of harmful contamination, dirt, moisture, and gross degradation. In this type of three phase induction motor the rotor is wound for the same number of poles as that of stator but it has less. I will tell you about the construction of wound rotor induction motor in the first section.
Rotor winding monitoring induction motors iris power. With a liquid rheostat, or a static secondary speed control, the wound rotor is an important alternative drive where limited range adjustable speed is required. 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. A new soft starting method for woundrotor induction motor.
Oct 30, 2018 rotor induced emf referred to stator mathemath mathsemath where s is slip and e is stator induced emf. Speed regulation of induction motors with wound rotor. It is mostly used in industrial drives because it is very reasonable and vigorous, economical and reliable. Abb slipring modular motors abb high voltage induction. If the speed is increased further the torque becomes negative and the machine begins to act like a generator rather than a motor.
Performance parameters control of wound rotor induction motor using ann controller. For those watercooling motors or using bearings with watercooling coils, please make sure the water already dried off to prevent tube corrosion or danger of frost. In the second section, i would be throwing light on the operation and working principle of wound rotor induction motor. Laminations from typical squirrelcage induction motor rotors, showing the cross. Typically k r is in the range of 1 to 5, and k x is in the range of 0. It is very commonly used in industries because it is very cheap, robust, efficient, and reliable. How an induction motor works by equations and physics. Instead of a series of rotor bars, a set of insulated rotor coils is used to accept external impedances.
Induction motors combine outstanding performance with an advanced longlife design. General principal construction phase wound rotor mathematical proof relation between torque and rotor power factor condition for maximum starting torque rotor e. The main advantage of solid rotor induction motors is their robust construction. In the case of a squirrel cage induction motor, the rotor is inaccessible and rotor circuit resistance is xed, whereas the wound. Induction motor output, losses and efficiency my tech info. This final thesis will mostly be dedicated to induction motors but also to synchronous permanent magnet and reluctance motors. In both induction and synchronous motors, the ac power supplied to the motor s stator creates a magnetic field that rotates in synchronism with the ac oscillations. Pdf induction motors have been the workhorse of industry since decades. Oct 10, 2016 a wound rotor induction motor is also known as slip ring induction motor. Whereas a synchronous motor s rotor turns at the same rate as the stator field, an induction motor s rotor rotates at a somewhat slower speed than the stator field. When the 3 phase stator windings are fed by 3 phase supply, a magnetic flux of constant magnitude which is rotating at synchronous speed is set up. Wound rotor motors deliver speed control of heavy and hightorque loads. High quality wound rotor induction motor from huapu motor, made by a reliable manufacturer from china. Exercise 1 threephase woundrotor induction machine with a.
Q during the stator design of a 3 phase, 30 kw, 400volts, 6 pole, 50hz,squirrel cage induction motor following data has been obtained. X depend on the shape and size of the rotor slot, the conductor material and the rotor current frequency. Diagnostics of rotor and stator problems in industrial induction motors. For the wound rotor threephase induction motor, the main equations are presented and a structure for the mathematical model is developed that makes it possible to calculate transients in the electric motor and the electric drive taking into consideration the distributed winding, saturation, and eddy currents in the stator and rotor teeth. Wound rotor induction motors master line wound rotor. The regulation of speed is required in many applications of induction motors, including in electric locomotives and electric driving vehicles.
Mathematical model of the woundrotor threephase induction motor. I think its necessary to point out what i think is a minor flaw in some of the earlier postings regarding dc shunts, hall effect etc. What makes the wound rotor motor a unique induction machine is its rotor. Reference 18 presented a novel toroidally wound permanent magnet machine. Wound rotor induction motor the engineering projects. Controlling the rotor resistance allows for controlling the starting current, the speed, and the torque. In a wrim, the rotor current will be ac, not dc as it is in a synchronous exciter system. Measuring rotor current in wound rotor motor electric.
Abb induction motors for the mining industry english pdf leaflet. Pdf starting of a threephase induction motor using a starter rheostat in rotor circuit has some disadvantages. Wound rotor tecowestinghouse motor company, a world. Connect the power input of the data acquisition and control interface to a. Typical characteristics of woundrotor induction motors. Electric motor electric motor construction of induction motors. 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 wound rotor with sliprings. Equivalent circuit model of novel solid rotor induction motor with. Their sole purpose is to allow resistance to be placed in series with the rotor windings while starting.
Instead of a series of rotor bars, a set of insulated rotor coils is. The stator frame consists of laminations of silicon steel, usually with a thickness of about 0. A wound rotor 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. We can derive an equation from the equivalent circuit that allows the calculation of the torque for a given value of slip. When the 3phase stator windings, are fed by a 3phase supply then, as seen from above, a magnetic flux of constant magnitude, but rotating at synchronous speed, is set up. Wound rotor tecowestinghouse motor company, a world leader. Record all nameplate information for the induction motor. Current signature analysis is important in tool in preventing. Induction motors have been ruling the industrial world for many decades. Induction motor general principle electromagnetism. Calculate the main dimensions, turns per phase, number of slots,number of conductors, cross section and slot area of a 250 h.
A universal motor includes a wound rotor and a stator. Squirrel cage rotor construction can be stated as follows lamination or motor core material are stacked in cylindrical shape, metal bars are placed in to this lamination slots perpendicularly. For three phase motors, connection type is either star y or delta ac motor winding continuity test using a multimeter, check the continuity of motor winding from phase to phase u to v, v to w, w to u. The torque developed in this method is proportional to the square of the supply voltage. In high slip region, induced torque actually decreases with increased load, since the increase in rotor current is completely overshadowed by decrease in rotor p. Introduction is there ever enough information at hand to analyze a motor problem. Construction of three phase induction motor electrical4u. We give balanced 3 phase current distributed in time to balanced 3 phase winding distributed in space located at rotor in this case, you may call it. Radhi key words harmonics, induction motor introduction the most elementary type of rotor used in induction motors is the solidsteel rotor, which offers.
Srim, results in a solid rotor induction motor with toroidal winding twsrim that combines the. The most common causes of induction motor failures are due to breaks in rotor bars or shorted circuit rings due to rotor eccentricity. Jzr2 yzr series ac crane lifting wound rotor slip ring motors. The working of an induction motor can be summarized as, the stator winding produces magnetic field and due to electromagnetic induction a current is induced in rotor which produces torque. The main drawback of this method is the requirement of high value of capacitance order of farad required to operate the machine closes to rotor resonance conditions.
Open the motor, find out the problem, and connect the wires again. The master line motors stand out for the flexibility of their electrical and mechanical design, resulting in a highperformance product, complying with the international standards and aligned with the global trends. Pdf dynamic analysis of seriesconnected wound rotor. Induction motor classification of ac motors induction motor. These three increased losses combine to increase the in put for a given.
465 1335 894 191 758 785 1436 245 749 103 1295 694 976 927 896 1505 820 595 119 876 1344 635 288 1374 931 1254 495 73 452