A disadvantage of the cage induction motor is the large starting current, which is about 5 to 7 times normal fullload current. Horizontal squirrel cage mediumvoltage induction motor. The field windings in the stator of an induction motor set up a rotating magnetic field through the rotor. Stator winding spreading the coil in this manner creates a sinusoidal flux distribution per pole, which improves performance and makes the motor less noisy sound and electrically. A motor rating of 10 horse power, 415 volts with 1440 rpm and 4pole is selected for design problem and an equivalent circuit model is developed to find out the various. What is the difference between a squirrel cage motor and a. Search wegthreephaseinductionmotorstlinesquirrelcage. Almost 70% of the industrial motors and drives comes under these category. Wound rotor induction motor the engineering projects. The basic idea of an electric motor is to generate two magnetic fields. Abstract the paper presents a novel control method for direct. The construction of a stator for both of the kinds of three phase induction motors is identifcal, and is discussed briefly below. In such machines there is no need to insulate the conductors from the iron. Former is cheaper and broadly used as it requires less maintenance than later one.
Types of ac induction motor rotors there are twotypes of rotor windings. Depending upon the type of rotor construction used the three phase induction motor are classified as. The rotor is same as that employed in 3phase squirrel cage induction motor. Slip ring induction motor or wound induction motor or phase wound induction motor. Suitable applications include small grinders, blowers, and lowstarting torque. The study of steady state operation of squirrel cage induction machines may be seen from the point of view of the theory of circuits with periodically variable mutual inductances. In most induction motors, the rotor winding is of the squirrelcage type where solid conductors in the slots are shorted together at each end of the rotor iron by. Rotor induction motor at noload and fullload to observe speed control using an. Know about the most popular and almost unbreakable construction of squirrel cage induction motor. The squirrel cage induction motor was designed for an extended service life under very demanding conditions. This chapter presents the essential features of the design, construction, and manufacture of squirrel cage induction rotors.
The auxiliary winding is also known as starting winding. Threephase sinusoidal balanced excitation in 3 stator phases produces a sinusoidally distributed field rotating at the excitation frequency. The squirrel cage induction motor scim functions by applying a voltage to the stator winding and inducing a voltage across the air gap in the rotor circuit. Stator of this motor is the same as the one used in squirrel cage induction motors. Squirrel cage induction motor and wound rotor induction motor. Determination of the torquespeed characteristic of. Mainly we discuss a threephase squirrel cage induction motor. A 3 phase induction motor can be used for different applications with various speed and load requirements. Oct 09, 2016 a 3 phase induction motor has two types based on the rotor construction, named as. Electric motors and machines, squirrel cage ac induction motor. This presents voltage drop problems to the electrical supply system to which it is connected and can create some difficulties in providing adequate electrical protection, e. It consists of a cylinder of steel laminations, with aluminum or copper conductors embedded in its surface. Please have a look at the below figures of squirrel cage induction and wound rotor slip ring induction motor.
High voltage induction motors are available as nseries general purpose motors and aseries engineered motors. The squirrel cage winding of a synchronous machine will generally be smaller than for an induction machine of similar rating. This exploded view of a leeson electric ac induction motor shows the stator windings, rotor in. The squirrel cage rotor consists of a lamination stack with slots to accommodate some number of rotor bars and shorting end rings that tie all the bars together. It is simple and relatively inexpensive, and the absence of sliding contacts in the squirrel cage machine reduces maintenance to a minimum.
And in the previous article on types of electrical motors, we have classified induction motors based on the type of rotor used. The induced torque of the motor is zero at synchronous speed. The curve is nearly linear in normal operating conditions which are between pullout speed and synchronous speed 6. Nseries general purpose motors combine costefficient standardized designs and short lead times with safety, productivity, energy efficiency and reliability. Direct torque and flux control of squirrel cage induction motor. The motor heating may be excessive unless the duty factor is low. May 20, 2015 the threephase induction motor the squirrelcage induction motor the woundrotor induction motor 3 4. A wound rotor induction motor has a stator like the squirrel cage induction motor. The typical base speed of the four pole induction motor varies between 1420 and 1480 rpm at 50 hz, while the synchronous speed is 1500 rpm at 50 hz. Pdf squirrel cage rotor design and manufacturing for. And on the other hand, when designed to have a high impedance, the motor has an increased amount of torque in a lowspeed range. Squirrel cage induction motor an overview sciencedirect topics.
Typical torquespeed curve of a squirrel cage induction motor given in figure 1 provides information about the operation of induction motor. In a squirrel cage induction motor, the rotor has conductive bars embedded in slots in the laminations, running the length of the rotor. In this work a conventional three phase squirrel cage type induction motor with specifications 10 hp, 415v, stardelta connected and 4 poles is chosen for comparison with our motor, which is designed for good efficiency. The absence of a centrifugal switch eliminates the possibility of motor failure due to faulty centrifugal switch mechanisms. These motors are very robust in construction and very cheap. Squirrel cage induction motor the engineering projects. A synchronous motor may have a squirrel cage winding embedded in its rotor, used to increase the motor starting torque and so decrease the time to accelerate to synchronous speed. Studying and improving of squirrel cage induction motor scim efficiency is a continuous area of interest not only among the researchers but also the industry, manufacturer and government. The rotor conductors are not placed exactly parallel to the shaft but are skewed by one slotpitch to reduce cogging torque, and this allows the motor to run quietly. We saw the construction of the squirrel cage induction motor. Three phase induction motors electric motors bharat bijlee. By far the most commonly used ac motor is the induction motor.
Control of motorcharacteristics by squirrelcage rotordesign the reactance x2 in an induction motor equivalent circuit represents the referred form of the rotors leakage reactance. Dont worry, difference between squirrel cage and slip ring type induction motor is tabulated after the figure. 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. Construction of squirrel cage induction motor explained. Bharat bijlee manufactures a complete range of three phase squirrel cage induction motors. Physical construction of the squirrel cage induction motor. Electric motor construction of induction motors britannica. How are squirrel cage induction motors constructed. Mostafa elshahed objectives learn a brief history of the electrical power systems construction. Heavy duty rotor construction compact size and simple installation.
It provides knowledge for industrial engineers, who use motor current signature analysis mcsa to determine if there are any cage winding breaks in their squirrel cage induction motors. All questions related to transistor will be clear here by blogs. Menzel squirrel cage induction motors are manufactured for various industries and industrial applications of all kinds. List and describe the more commonly used equipment in an electric substation. What is a squirrel cage motor and how does it work. They are targeted at applications where a highly customized motor is not needed. Reaction of a squirrelcage rotor in a 2pole field in the rotor reference frame.
The rotor is constructed using a number of single bars shortcircuited by end rings and arranged in a hamsterwheel or squirrel cage configuration. Know about the construction of double squirrel cage motor with a graphical comparison with single cage. Characteristics of induction motors nidec corporation. Review on efficiency improvement in squirrel cage induction motor by using dcr technology subramanian manoharan. Standard types of squirrel cage motors are as explained below. These motors are tested to strict quality control for routine and type tests at every stage of production and are ideally suitable for various industrial applications. 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. Kanpur, india design of a three phase squirrel cage induction motor for electric propulsion system ravi prakash,mohammad junaidakhtar, r. A squirrelcage rotor is the rotating part of the common squirrelcage induction motor. The relative motion between this field and the rotation of the rotor induces electric current in the conductive bars.
Differentiate between the various types of generating electric power stations. Oct 10, 2016 after that, i will tell you some of the key features and uses of wound rotor induction motor. Induction motors are used in applications requiring fast and precise control of torque, speed, and. This model, while sacrificing the finer details of construction, yields, through direct integration of. The squirrel cage induction motor was designed for an extended service life under very demanding. Slipring or woundrotor induction motors construction of squirrel cage induction motor. Omar almukhtar universitylibya benha university, egypt. Api std 547 generalpurpose formwound squirrel cage induction motors 185 kw 250 hp through 2240 kw 3000 hp, second edition.
This field can be viewed as being created by a single equivalent sinusoidal winding which is excited with dc current and which is also rotating. Normally, we use the motors in industrial drives because they are rugged, reliable and economical. Squirrel cage induction motors menzel elektromotoren. But increasing the rotor resistance for improving starting torque is not advisory as it will reduce the efficiency of the motor due to more copper loss.
Nov 27, 2019 the three phase induction motor is the most widely used electrical motor. Pdf this article tells detail about three phase squirrel cage induction motor construction, working principle, and calculations, after reading this. The majority of commercial and industrial applications usually involve the use of a threephase squirrel cage induction motor. Other articles where squirrelcage rotor winding is discussed. 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. All the above types of cage winding have been used for power station applications, the choice depending on the power output and speed of the motor, the.
Squirrel cage motors are the most commonly used induction motors, but the main drawback in them is their poor starting torque due to low rotor resistance. The shaded pole induction motor has no commutator, brushes, collector rings, contactors, capacitors or moving switch parts, so it is relatively cheaper, simpler and extremely rugged in construction and reliable. An induction motor can therefore be made without electrical connections to the rotor. This rotating magnetic field has a speed which is known as the synchronous speed. For motors up to about 300 kilowatts, the squirrel.
Squireel cage induction motors are widely used in industries. As in other induction motors, the basic parts are stator and rotor. Poloujadoff laboratoire delectrotechnique, universites. An induction motors rotor can be either wound type or squirrel cage type. Designing of three phase squirrel cage induction motor for. These bars are shorted at each end with shorting rings. In squirrel cage induction motors, rotor windings wound in squirrel cage. Squirrel cage wound rotor with slip rings the rotating magnetic field the basic idea of an electric motor is to generate two magnetic fields. These ie3 motors comply with the latest efficiency standards and requirements of is. Deivasahayam gopalakrishnan ranganathan induction motors account for approximately 50% of the overall electricity use in industrialized countries. Third international conference on advances in control and optimization of dynamical systems march 15, 2014. Suitable applications include small grinders, blowers, and lowstartingtorque applications. Difference between squirrel cage and slip ring induction. Squirrel cage induction motors are very widely used in both fixedspeed and variablefrequency drive applications.
The rotor is not power supplied externally and the currents that flow through it are induced. Construction of three phase induction motor electrical4u. Three phase induction motors used in explosive atmospheres w60 line squirrel cage rotor horizontal date. The figure itself depicts many difference between the two types of motors.
The microchip name and logo, the microchip logo, accuron. Pdf design and analysis of squirrel cage induction motor in short. A highspeed squirrel cage induction machine requires totally different design compared to the traditional squirrel cage industrial motor because of mechanical limitations caused by the high speed. The polyphase induction motor the polyphase induction motor is the most commonly used industrial motor, finding application in many situations where speed regulation is not essential. Also appreciate the rugged construction of squirrel cage rotor and know the spectacular reasons for the skewed arrangements of the rotor conductors. A capacitor start capacitor run induction motor is a single phase motor consists of a stator and a single cage rotor. Introduction this manual provides information on how to safely install, couple to the driven equipment, and maintain the toshiba squirrel cage mediumvoltage induction motor. The sinusoidally distributed flux density wave is moving at slip speed inducing in the rotor cage voltages of magnitude indicated by the blue vertical lines. There are two types of 3phase induction motor based on the type of rotor used. This final thesis will mostly be dedicated to induction motors but also to synchronous permanent magnet and reluctance motors. Pdf squirrel cage induction motors are very popular in industrial and. Advantages and disadvantages of squirrel cage induction motor.
Most of single phase induction motors use squirrel cage rotor as it has a remarkably simple and robust construction enabling it to operate in the most adverse circumstances. Reaction of a squirrel cage rotor in a 2pole field in the rotor reference frame. Pdf three phase squirrel cage induction motor, construction. What are the specific applications of squirrel cage and. Design, construction, and manufacture of squirrel cage. Design of a three phase squirrel cage induction motor for. Low voltage tefc frame electric motors to iec60034 ratings from 0,37kw up to 450kw at 400v, 525v and v premium efficiency to iec 6003430 ie3 enclosure ip66 and class h insulation description premium efficiency ie3, class h insulation, ip 66 cast iron squirrel cage. When a 3 phase supply is given to the stator winding it sets up a rotating magnetic field in space.
In traditional designs of 60 hz linefed induction machines, skin effect is represented by correction coefficients k r and k x for bar resistance and slot leakage inductance. Faculty of engineering tobruk, faculty of engineering benha2 1, 2. Pdf design of a threephase squirrelcage induction motor. Typically, the fullload slip for the squirrel cage induction motor is less than 5%. The 3phase set of currents, each of equal magnitude and with a phase. The rotor is separated from the stator by a small airgap which ranges from 0.
The majority of commercial and industrial applications usually involve the use of a threephase squirrelcage induction motor. Insidepenton com electronic design adobe pdf logo tiny. What characterizes an induction motor is the fact that only the stator is connected to the power supply. A synchronous motor may have a squirrelcage winding embedded in its rotor, used to. A squirrelcage rotor is the rotating part of the common squirrel cage induction motor. A 1phase induction motor is similar to a 3phase squirrel cage induction motor in physical appearance.
An anisotropic homogeneous representation for both squirrelcage rotor and stator windings is used. The main difference between slip ring and squirrel cage induction motor is the rotor construction. Pdf improving squirrel cage induction motor efficiency. Ac motor basics to introduce the principle of operation of an ac induction motor and discuss the basic construction ac motor calculations calculating mechanical power requirements, torque speed curves, numerical calculation, sample calculation, thermal calculations. The principle of working of squirrel cage and slip ring induction motor is based on faradays law of electromagnetic induction. Jul 23, 2016 please have a look at the below figures of squirrel cage induction and wound rotor slip ring induction motor. The actual fullload slip of a particular motor is dependant on the motor design.
Speed control of wound rotor induction motor pdf objective. Squirrel cage rotor almost 90 per cent of induction motors are squirrel cage type, because this type of rotor has the simplest and most rugged construction imaginable and is almost indestructible. Basic operation of the induction motor as previously shown, the phase displacement between the voltages applied to the stator windings produces a travelling mmf or rotating magnetic field in the uniform air gap. There are two types of induction motors, one with wound type rotor, also called slipring motor and another one with squirrel cage rotor. The performance of the motor due to full pitch and short pitch winding. Squirrel cage construction, the rotor winding consists of a number of rotor bars, shortcut by rings from both side, see figure below. A 3 phase induction motor has two main parts i stator and ii rotor. Jul 25, 2019 squirrel cage induction motor working principle.
Because of its simple and rugged construction, about 95% of the induction motors use the squirrel cage rotor. Double squirrel cage motor we have already discussed that the rotor which is of squirrel cage type has two end rings, which are permanently shorted with the rotor conductors. A 3 phase induction motor has two types based on the rotor construction, named as. Torquespeed characteristics of three phase squirrel cage induction motor aim to obtain the torquespeed characteristics tn r of a three phase squirrel cage induction motor using 1. The rotor of a threephase squirrel cage induction motor consists of a set of noninsulated bars that are interconnected by shortcircuit rings. In operation, the nonrotating stator winding is connected to an alternating current power source. Oct 19, 20 three phase squirrel cage induction motor with inverter section model 0100hz. Motors of this type employ squirrel cage having relatively low resistance and reactance.
Almost 95% of the induction motors used is of squirrel cage type. An887, ac induction motor fundamentals microchip technology. This article presents an understanding of what squirrel cage induction motors. When a motor is designed in such a way that impedance of the aluminum conductor of the rotor is reduced, its efficiency is increased in a highspeed range. Squirrelcage rotor winding machine part britannica. This work is introducing the designing of new three phase squirrel cage induction motor with an objective of getting good efficiency. The rotor is constructed using a number of single bars shortcircuited by end rings and arranged in a hamsterwheel or squirrelcage configuration. Variable voltage variable frequency vf control theory an induction motor compared to a dc motor has some major advantages such as. Starting torque is directly proportional to the rotor resistance. Menzel squirrel cage motors are available in all standard motor cooling and protection types for lowvoltage from 75 kw as well as medium and high voltage up to 25,000 kw. Parida department of electrical engineering national institute of technology, silchar,assam, india email. However, should the motor require service, this manual includes a section that assists the. Shaded pole induction motors working and construction.
This rotor is made up from parallel aluminum or copper bars. Recall that leakage reactance is the reactance due to the rotor flux lines that do not also couple with the stator windings. Torquespeed characteristics of three phase squirrel cage. The rotor will constantly be turning to align its magnetic field with that of the stator field. Lecture 6 three phase induction motors cairo university. Cage induction motor an overview sciencedirect topics. Working principle of 3 phase squirrel cage induction motor. The theory of three phase induction squirrel cage motors.
The torque of the induction motor depends on the rotor resistance. Control of motorcharacteristics by squirrelcage rotordesign. Dec 10, 2015 watch this video and learn basics of squirrel cage induction motor. 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 the other applications you will see a simpler, squirrel cage type of rotor. The design and construction of the stator and rotor of an induction generator are similar to that of a large induction motor having a squirrel cage rotor. There is uniform air gap between stator and rotor but no electrical connection between them. Discussed and described are the stator windings, the rotor shortcircuited cage. Firstly, i am going to tell you about the structure of squirrel cage induction motor. Design of a threephase squirrelcage induction motor based on efficiency maximization using fem software mucet2008paper no here.
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