Ac motors dc motors permanent magnet series wound shunt wound compound wound singlephase polyphase universal motors induction synchronous induction synchronous squirrel cage wound rotor shaded pole hysteresis reluctance permanent magnet wound rotor squirrel cage splitphase capacitorstart permanent split capacitor capacitor startrun shaded. The squirrel cage induction motors are 90% used in various industrial, domestic and commercial applications. Ac motors polyphase peerless electric designs 3phase motors from 120 to 50 hp in various frame sizes from 4. The torque produced at a given rpm is not constant, but pulsates at twice the line frequency around a median value. A 3 phase induction motor can be used for different applications with various speed and load requirements.
Tesla polyphase induction motors ac motors electronics textbook. For motors falling outside this description, the more comprehensive model specifications below are recommended. Wound rotor induction motors ac motors electronics. Nikola tesla 18561943 invented the polyphase ac induction motor not as a result of intense research, but surprisingly, while on vacation. These induction motors require special attention during its design. Squirrelcage rotor almost 90 per cent of induction motors are squirrelcage type, because this type of rotor has the. Third international conference on advances in control and optimization of dynamical systems march 15, 2014. These bars are shorted at each end with shorting rings. The effect of unbalanced voltages on polyphase induction motors is equivalent to the. In a squirrel cage induction motor, the rotor has conductive bars embedded in slots in the laminations, running the length of the rotor. Latest polyphase induction motors multiple choice questions. Almost 95% of the induction motors used is of squirrel cage type. On the other hand, the polyphase induction motor shown in cutaway in fig. Most common ac motors use the squirrel cage rotor, which will be found in virtually all domestic and light industrial alternating current motors.
Construction of squirrel cage induction motor explained. In this method we directly switch the stator of the three phase squirrel cage induction motor on to the supply mains. Polyphase induction motors mcqs answers pdf electrical engg. Search wegthreephaseinductionmotorstlinesquirrelcage. Iec ac squirrel cage induction motor specification. They are socalled squirrel cage motors because the shape of their rotor the. A squirrelcage rotor is the rotating part of the common squirrelcage induction motor. Electromagnetic fields inside induction motors have been studied before the. Pdf speed control of multiphase cage induction motors. The rotor is constructed using a number of single bars shortcircuited by end rings and arranged in a. Nema classes for polyphase squirrel cage induction motors.
Differentiate between the various types of generating electric power stations. The vibration of squirrelcage induction motors usually. Mostafa elshahed objectives learn a brief history of the electrical power systems construction. Reference mg 1 for specific design letter information based on motor horsepower, speed. The three phase induction motor is the most widely used electrical motor. Information guide for general purpose industrial ac small. Closedform analysis of squirrelcage induction motors with. Motors with nameplate volt ages different than those listed in tables 1 or 2 should be referred to the company. Squirrelcage induction motor the operation of the squirrelcage motor is.
Available squirrel cage induction motor starting methods include directonline starting, reducedvoltage reactor or autotransformer starting, stardelta starting or, increasingly, new solidstate soft assemblies and, of course, variable frequency drives vfds. This rotating magnetic field has a speed which is known as the synchronous speed. 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. Kanpur, india design of a three phase squirrel cage induction motor for electric propulsion system ravi. This method is also known as the dol method for starting the three phase squirrel cage induction motor. Their sole purpose is to allow resistance to be placed in series with the rotor windings while. Nema mg 1, motors and generators provides design letters for polyphase induction squirrel cage medium motors. Control of motorcharacteristics by squirrelcage rotordesign the reactance x2 in an induction motor equivalent circuit represents the referred form of the rotors leakage reactance. This way, designers can make informed choices when choosing the right motor. Particularly, the squirrel cage type is simplicity, robustness and low cost, which has always made it very goodlooking and therefore, captured the leading place in industrial sector.
In that period, some estimates surpassed thirty million polyphase induction motors. The squirrel cage refers to the rotating exercise cage for pet animals. Design of a three phase squirrel cage induction motor for electric propulsion system. The motor takes its name from the shape of its rotor windings a ring at either end of the rotor, with. A 3 phase ac induction motor photoed by hordu motor. Analysis and design of ac induction motors with squirrel cage. Why the starting torque of squirrel cage induction motor is low. It is simple and relatively inexpensive, and the absence of sliding contacts in the squirrel cage machine reduces maintenance to a minimum. The efficiency shall be identified on the nameplate by the. Jul 25, 2019 squirrel cage induction motor working principle. Efficiency of polyphase squirrelcage medium motors with continuous ratings nominal efficiency column in table 50 which shall be not greater than the average efficiency of a large population of motors of the same design.
Now let us discuss in detail, the most common form of induction motor, the squirrel cage induction motor. 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. Woundrotor motors are also available, usually for special application where external resistance is applied to the rotor for speed control, as described later. In the circle diagram for induction motor, the diameter of the circle represents. Squirrel cage induction motor the operation of the squirrel cage motor is.
Design of a three phase squirrel cage induction motor for. Squirrel cage motors are a subclass of induction motors, which harness electromagnetism to generate motion. Pdf improving squirrel cage induction motor efficiency. Threephase currents flowing within the stator create a rotating magnetic field which induces a current and consequent magnetic field in the rotor.
However, should the motor require service, this manual includes a section that assists the. The torque produced at a given rpm is not constant. Around 1950, about fifteen million singlephase induction motors were produced annually. Ac induction motors are also the most common motors used in main powered home appliances. Advantages of three phase squirrel cage induction motor. Analysis and design of ac induction motors with squirrel cage rotors. Pdf the subject of this paper is the control possibility of the multiphase cage. Those design letters provide information regarding lockedrotor torque, pullup torque, and slip values at rated torque and are shown in table 8. The squirrel cage induction motor was designed for an extended service life under very demanding conditions. Information and recommendations for the engineer fe1100. The majority of commercial and industrial applications usually involve the use of a threephase squirrelcage induction motor. The most common type of motor in this group is the squirrel cage polyphase induction motor so called because the rotor is constructed like a squirrel cage fig. Polyphase induction motors mcqs part1 polyphase induction motors mcqs part2 polyphase induction motors mcqs part3 polyphase induction motors mcqs part4 polyphase induction motors mcqs part5. Nema mg 1, motors and generators provides design letters for polyphase induction squirrelcage medium motors.
The most common type of motor in this group is the squirrel cage polyphase induction motor so called because the rotor is constructed like a. We use starters in order to limit the high starting current. Recall that leakage reactance is the reactance due to the rotor flux lines that do not also couple with the stator windings. This article presents an understanding of what squirrel cage induction motors are and.
Tesla polyphase induction motors ac motors electronics. 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. What is a squirrel cage motor and how does it work. The squirrel cage induction motor was designed for an extended service life under very demanding. Those induction motors which employ squirrel cage rotor are called squirrel cage induction motors. Due to the simple rotor construction, the squirrel cage motor is rugged and durable, and is the most common type. Introduction this manual provides information on how to safely install, couple to the driven equipment, and maintain the toshiba squirrel cage mediumvoltage induction motor.
Squirrel cage wound rotor with slip rings the rotating magnetic field the basic idea of an electric motor is to generate two magnetic fields. Pdf polyphase induction machines nasrin shaheen academia. Model repair specifications for low voltage induction motors. It is very commonly used in industries because it is very cheap, robust, efficient, and reliable. Starting methods for polyphase induction machine electrical4u. Class 8736 starters consist of one class 8502 contactor and one class 8536 starter mechanically and electrically interlocked.
Pdf noise of polyphase electric motors researchgate. Analysis and design of ac induction motors with squirrel. Our polyphase squirrel cage induction motors are designed for across the line or increment starting as required. Wegthreephaseinductionmotorstlinesquirrelcagerotor12364818manualenglish. Their sole purpose is to allow resistance to be placed in series with the rotor windings while starting figure below. Latest polyphase induction motors multiple choice questions and answers pdf 31. Realtime polyphase induction motors multiple choice. Home electrical engineering multiple choice questions 110 top most polyphase induction motors electrical engineering multiple choice questions and answers.
Three phase induction motors w60 line squirrel cage rotor horizontal. Kanpur, india design of a three phase squirrel cage induction motor for electric propulsion system ravi prakash,mohammad junaidakhtar, r. In squirrel cage induction motors, the rotor slots are usually given slight skew in order to. Designing of three phase squirrel cage induction motor for. The electric energy generated purchased by consumers for different needs. Notice and disclaimer the information in this publication was considered technically sound by a consensus among persons engaged in its development at the time it was approved. Advantages of 3 phase induction motor generally easy to build and cheaper than corresponding dc or synchronous motors induction motor is robust. Horizontal squirrel cage mediumvoltage induction motor. A polyphase induction motor consists of a polyphase winding embedded in a laminated stator and a conductive squirrel cage embedded in a laminated rotor. The squirrelcage motor is the simplest to manufacture and the easiest to maintain. Control of motorcharacteristics by squirrelcage rotordesign. Induction motors are favored due to their ruggedness and simplicity. The squirrel cage motor is the simplest to manufacture and the easiest to maintain.
The rotor consists of a cylindrical lamina ted core with parallel slots for carrying the rotor conductors which, it should be fig. 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. On the following pages the basic operation and types. 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. It is low cost and requires low maintenance in comparison with other motor types. Polyphase induction motors mcqs answers pdf electrical. The rotor is constructed using a number of single bars shortcircuited by end rings and arranged in a hamsterwheel or squirrel cage configuration. This article will explain the principles of squirrel cage motors, how they operate, and what kinds of applications they are used for.
When a 3 phase supply is given to the stator winding it sets up a rotating magnetic field in space. For squirrelcage motors this peaktorque slip is relatively small, much as is shown. Normally, we use the motors in industrial drives because they are rugged, reliable and economical. Let us consider first squirrel cage type of induction motor. 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. This practice covers motors that are totallyenclosed fancooled ic 411 type, premium efficiency ie3, aircooled, with ip 54 degree of protection for motors and auxiliaries, and with. In operation, the nonrotating stator winding is connected to an alternating current power source. It converts electrical energy into mechanical energy and it is used to provide motion. The squirrel cage induction motor is the most commonly used motor in industry. Squirrel cage wound rotor with slip rings the rotating magnetic field. Wound rotor induction motors ac motors electronics textbook. Information guide for general purpose industrial ac small and. Model repair specifications for low voltage induction motors these model repair specifications are intended to cover routine repair and rewind of lowvoltage randomwound threephase ac squirrel cage induction motors.
It consists of a cylinder of steel laminations, with aluminum or copper conductors embedded in its surface. Most of 3phase induction motors use squirrel cage rotor as it has a remarkably simple and robust construction enabling it to operate in the most adverse circumstances. Most of 3phase induction motors use squirrel cage rotor as it has a remarkably simple and robust construction enabling it. The majority of commercial and industrial applications usually involve the use of a threephase squirrel cage induction motor. Realtime polyphase induction motors multiple choice questions. Nema mg 102001 energy management guide for selection and use of fixed frequency medium ac squirrel cage polyphase induction motors. Stator and rotor air gap fluxes, the interaction of which produces useful. Working principle of 3 phase squirrel cage induction motor. The squirrelcage refers to the rotating exercise cage for pet animals. 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.
In order to understand the speed control, theory and methods, it is important that the basic theory of the controlled component i. A simple explanation of squirrel cage induction motors. Selfstarting polyphase induction motors produce torque even at standstill. It is simple and relatively inexpensive, and the absence of sliding contacts in the squirrelcage machine reduces maintenance to a minimum. The threephase induction motor is the extensively used for various kinds of industrial drives. And in the previous article on types of electrical motors, we have classified induction motors based on the type of rotor used. The reason for the name squirrel cage is because of the type of rotor used in these motors. In order to choose a starting method for a squirrel cage motor, we have three main considerations. Both voltages are standard for the particular rating as listed in tables 1 and 2.
We use different starters for both the type of three phase induction motors. Rotor induction motor an overview sciencedirect topics. Learn the working principle and applications of a squirrel cage induction. Construction of three phase induction motor electrical4u. Dual voltage motors polyphase and singlephase motors may be furnished as dual voltage ratings under the following conditions. Practicing all polyphase induction motors electrical engineering questions and answers in online helps you to improve your ability to attend the real time gate, ies and bsnl jto exams. There is no electrical connection between these bars.
Parida department of electrical engineering national institute of technology, silchar,assam, india email. We classify starting methods for squirrel cage induction motor into two types on the basis of voltage. The most common type of motor in this group is the squirrelcage polyphase induction motor so called because the rotor is constructed like a squirrelcage fig. What is the difference between a squirrel cage motor and a.238 428 362 770 1443 1219 1153 1232 218 1541 1017 1535 25 625 746 569 1208 848 775 1074 1475 1339 585 20 698 1368 787 821 600 869 436 1228 318 131 1220 219 1310 1138 901 1151 964 1009 648 1415 474 1071 562