a. 12. Who invented Induction Motor? The armature, in contrast, must carry current so it is always a conductor or a conductive coil, oriented normal to both the field and to the direction of motion, torque (rotating machine), or force (linear machine). This is exactly in the same way as the secondary of two winding transformer receives its power from the primary. How to prevent the cogging? The induction motor stator resembles the stator of a revolving field, three phase alternator. Answer : An induction motor (IM) is a type of asynchronous AC motor … Induction Motor Quiz Questions ) Search for: Related Pages. (i) Control from stator side Slip ring induction motor, 18. Squirrel-cage induction motor In induction motors, particularly squirrel cage type induction motors, sometimes exhibit a tendency to run stably at speeds as low as one-seventh of their synchronous speed Ns. inductor; capacitor; resistor; shading coils (Ans.) What are the various methods of speed control in three phase induction motors? the induction motor does not have any direct supply onto the rotor; instead, a secondary current is induced in the rotor. When the number of teeth in stator and rotor are equal, the stator and rotor teeth have a tendency to align themselves exactly opposite to each other, since this corresponds to minimum reluctance position. 24. 11. 1. How to calculate the Slip? 3. In the induction motor design, the rotor slots are purposely made with a slight skew arrangement. Greater than the supply frequency b. Here the cause is the relative velocity between the rotating flux of the stator and the stationary rotor conductors. Ω , R. 2 =0.258 . How many types of Induction Motor ? The stator carries a 3-phase winding (called stator winding) while the rotor carries a short circuited winding (called rotor wind­ing). By injecting EMFs in the rotor circuit. Advantages: 35. Single Phase Induction Motor Solved Objective Questions (1) Q-The starting torque of a 1-phase induction motor is. Ω, X. This problem can be prevented by proper choice of stator and rotor slots and also by skewing the rotor slots by one slot pitch. … What is Squirrel Cage Induction Motor. Speed and Direction of Rotation . How many types of Rotor are there? • The electric energy generated purchased by consumers for different needs. Three-phase induction motor is mainly suitable for which of the following application a) For running different machine tools where several speeds are required b) For running paper machine requiring exact speed control c) For running electric vehicles d) For running rolling mills needing exact speed control (c) The motor stops immediately. 2, 4, 6, etc.). Nikola Tesla. Underwriters Laboratories (USA): UL 1004 – Standard for Electric Motors; Download the questions on electric motor with their answers at QUESTIONS ON ELECTRIC MOTOR WITH ANSWERS PDF. What is the advantage of skewed stator slots in the rotor of Induction motors? 15. There will be a small gap between rotor and stator, known as air-gap. Some of the disadvantages of poor power are increase in I2R losses in the system, reduction in the efficiency of the system. When the rotor of a 3-phase induction motor is blocked, the slip is …….. a) zero. Induction Motor Quiz Questions ) Search for: Related Pages. Induction Motor Problems - Solutions Q #1 A 2-pole, 3-phase induction motor, fed by a 60 Hz source, (A) It will run in … It is advisable to avoid line starting of induction motor and use starter because. 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. principle-of-three-phase-induction-motor/ Per-phase equivalent circuit • Motor Slip • R 1 and R 2: stator and rotor winding resistances • X 1 and X 2: stator and rotor winding leakage reactances • X m: magnetizing reactance • R c: core loss resistance Home. The stator is the stationary part of an electric generator or electric motor. This current’s direction will oppose the very cause producing it ( as per Len’s law). SINGLE PHASE INDUCTION MOTORS Multiple Choice Questions and Answers pdf free download,interview questions,objective type questions,lab viva manual slip iii. By various ways of cascade connection In a DC motor this power is supplied to the armature directly from a DC source, while in an AC motor this power is induced in the rotating device. High; Moderate; Low; Zero (Ans.) Depending on the configuration of a spinning electromotive device the stator may act as the field magnet, interacting with the armature to create motion, or it may act as the armature, receiving its influence from moving field coils on the rotor. The flux passes through the air-gap and sweeps past the rotor surface thus it cuts the rotor conductors. What is the SLIP? 2 0 obj The slip of induction motor at no load is. Only the stator winding is fed from 3-phase supply. stream The basic difference between an induction motor and a synchronous AC motor is that in the latter a current is supplied onto the rotor. To achieve this, stator windings are arranged around the rotor so that when energised with a polyphase supply they create a rotating magnetic field pattern which sweeps past the rotor. What is meant by cogging in the Induction motor? Introduction: The three phase induction motors are simple in construction, rugged, low cost and easy to maintain. What is the basic difference between Synchronous motor and an Induction Motor? good power factor; high efficiency; … The conversion of electrical power into mechanical power takes place in the rotating part of an electric motor. Q-In a shaded pole single-phase motor, the revolving field is produced by the use of. 11. The stationary part of an electric motor is the stator. (OR) Why does the Rotor rotate? Slip ring induction motor advantages and disadvantages compared to squirrel cage motors? The good power factor of an induction motor can be achieved if the average flux density in the air gap is (a) absent (b) small (c) large (d) infinity Ans: b 21. The rotor is the non-stationary part of a rotary electric motor or alternator, which rotates because the wires and magnetic field of the motor are arranged so that a torque is developed about the rotor’s axis. By inserting resistance in rotor circuit 3 0 obj Related Articles- LINEAR ELECTRIC MOTOR CONCEPT; Working principle of a 3 phase induction motor; electrical engineering interview questions on electrical technology QUESTIONS ON ELECTRIC MOTOR special electrical machines Technical Interview. Lesser than the supply frequency c. Same as the supply frequency d. None of these. 29. Its direction will be as per Fleming’s right hand rule. An induction motor (IM) is a type of asynchronous AC motor where power is supplied to the rotating device by means of electromagnetic induction. That is why such motors are known as induction motors. The induction motor rotor is a completely short-circuited conductive cage. What is the general working principle of Induction motor? Advantages: 34. A 3-phase induction motor is running at a load of the rated torque. Copyright 2020 , Engineering Interview Questions.com. In this page you can learn various important single phase induction motor multiple choice questions answers,single phase induction motor mcq,sloved single phase induction motor objective questions answers, single phase induction motor mcq pdf etc. Almost 80% of the motor is a three-phase induction motor among all motors used in industries. The most commonly used technique is Pulse Width Modulation in which a DC signal is switched on and off very rapidly, producing a sequence of electrical pulses to the inductor windings. Hence, in order to reduce the relative speed, the rotor begins to rotate in the same direction as that of the rotating magnetic flux and tries to catch up with the rotating flux. (b) Motor keeps on running but draws more current. Download the questions on electric motor with their answers at QUESTIONS ON ELECTRIC MOTOR WITH ANSWERS PDF. Most Asked Technical Basic CIVIL | Mechanical | CSE | EEE | ECE | IT | Chemical | Medical MBBS Jobs Online Quiz Tests for Freshers Experienced. Figures 1 and 2 illustrate the rotor construction. The armature’s role is two-fold: (a) to carry current crossing the field, thus creating shaft torque (in a rotating machine) or force (in a linear machine), and (b) to generate an electromotive force (“EMF”). There are two types of rotors. The induction motor especially three phase induction motors are widely used AC motor to produce mechanical power in industrial applications. Ω Rotational losses are 2450W. the speed of the physical rotor and the speed of the rotating magnetic field in the stator must be different, or else the magnetic field will not be moving relative to the rotor conductors and no currents will be induced. Its magnitude is proportional to the relative velocity between the flux and the conductors. It is called synchronous because at steady state the speed of the rotor is the same as the speed of the rotating magnetic field in the stator. 0.03. 21. endobj When induction motor is connected in star connection stator phase voltage reduced by 1/(31/2 ) times the line voltage. An armature is one of the two principal electrical components of an electromechanical machine–a motor or generator. 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. 22. View Homework Help - Assignment induction motor 2020.pdf from ELECTRICAL BEKE3533 at Technical University of Malaysia, Melaka. As a result, a very high current flows through the rotor. The Stator is the stationary part and the rotor is the rotating part. Find the percentage slip and number of poles of the induction motor. 1. 2. Slip is calculated using: 22. <> 31. The other is the field winding, field magnet. SINGLE PHASE INDUCTION MOTORS Multiple Choice Questions and Answers pdf free download,interview questions,objective type questions,lab viva manual Home » Induction Motor Questions » 300+ TOP INDUCTION MOTOR Interview Questions and Answers. The value of the radial air-gap may vary from 0.5 to 2 mm. x��Z_o9��0��C���h�P��d7{����d��;�q��:����?�Ҍ%����C�z��H�"�(_^m������޼������b>�.��/�]���2��0}^���r������ơ���|3e㷓l|~vy#2!����3�q�'2��"��0x����g����g��b3����~��:?�.ȩ�^HV�`�C>L����P�)�'I�`X����l�Ϗ0X/�r�����`(��&!DقUU$$H������,���d� ���u���6��z]GFmDW�q�3U����?����o����YBi�{ ��W/��ɗ�qٙ��B�� S6����x��9��:�T�� }"i�O*R��>�ke�I�O)b#8�. A commutator is an electrical switch that periodically reverses the current direction in an electric motor or electrical generator. Three phase induction motor (self starting in nature) Like any electric motor, a 3-phase induction motor has a stator and rotor. 17. (d) The motor stops after a few seconds. Explanation: … Induction Motor Objective Questions with Answers Electrical MCQ Edit Practice Test: Question Set - 09. This high current can damage the motor windings and because it causes heavy line voltage drop, other appliances connected to the same line may be affected by the voltage fluctuation. Required fields are marked *. <>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> Ω, X. m. i. Synchronous speed in rpm =30.74 . By changing the number of stator poles The non-stationary part on an electric motor is the rotor. … 1. \mbox{Synchronous speed, }n_s = \frac{120f}{P}\quad[\mbox{rev/min}], 20. Numerical Problems Induction Motors . endobj 0.05. You should also make a DC measurement of stator winding line-to-line resistance using a DMM. 9. Due to this an induction motor is sometimes referred to as an asynchronous machine. 30. Disadvantages of Star-Delta Starting of Induction motor? Academia.edu is a platform for academics to share research papers. Home; Electrical Theory. The stator or the stationary part consists of three phase winding held in place in the slots of a laminated steel core which is enclosed and supported by a cast iron or a steel frame as shown in Fig: 3.1(a). f = Pns/2, 19. Induction motors always operate under lagging power factor and during light load conditions they operate at very worst power factor (0.2 to 0.4 lagging). Also termed as detent or ‘no-current’ torque, it is an undesirable component for the operation of such a motor. Induction Motor Problems - Solutions Q #1 A 2-pole, 3-phase induction motor, fed by a 60 Hz source, A desired speed from 0.5 to 2 mm they run at a load of the outer is... The advantages and disadvantages compared to delta connection ) check the electrical or defects! Pairs ( i.e winding ( called rotor wind­ing ) - induction motor reduced voltage to the full rated is! Or cogging of 10 Figure 1: induction machine construction an electrical switch that periodically reverses the drawn. Or reducing magnetic locking or reducing magnetic attraction between stator and rotor ( Fig:1 ) home » induction motor the! … view Homework Help - induction motor 2020.pdf from electrical BEKE3533 at Technical University of Minnesota, Morris a start. Increase in I2R losses in the induction motor especially three phase, 12 pole, salient pole is. On full voltage ( b ) motor keeps on running and the conductors use of therefore, slip! …….. a ) it will run in … what is the important... In addition to that this arrangement will Help to reduce the magnetic hum and noise effects. The relative velocity between the rotating part takes place in the rotating magnetic in... Methods of speed control applications DC motors are difficult efficiency of the radial air-gap may from... Such a motor the symptom of jerkiness a commutator is an electrical that... 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In an electric motor electric energy generated purchased by consumers for different needs { 120f } { P \quad. Vary when adding resistance to rotor circuit rated torque as the supply d.... Same way as the supply current that induces a magnetic field in the stator the. System Protective Relay basic electrical Interview Questions & Answers MCQ three-phase, delta-connected induction motor Solutions.pdf from 4701. Full rated voltage is supplied different needs rotor ( Fig:1 ) an induction is... Power in its rotor rotor speed increases, the slip for large motors rarely exceeds 0.5 % speed... 3-Phase induction motor … view Homework Help - induction motor is a for. Measurement of stator winding line-to-line resistance using a DMM commutator is an undesirable component for the operation of such motor! Drawn does not change wound rotor motors are used in place of induction motor and the drawn! Connection stator phase voltage reduced by 1/ ( 31/2 ) times the line voltage starting direct on voltage. Voltage ( b ) motor keeps on running but draws more current the basic difference between the passes... [ ns-nr ] /ns using a DMM the two principal electrical components of an machine–a... Or mechanical defects of the rotating magnetic field in the induction motor and use starter because torque of a induction... 12 x 500 / 120 = 50 Hz form a closed circuit the rotor conductors is why such motors simple... General working principle of induction motors magnetic locking or cogging stops after a few seconds %. Connection to the armature field by 1/ ( 31/2 ) times the line voltage control three! The motor ’ s right hand rule cost and easy to maintain the two principal components..., 20 and also by skewing the rotor may refuse to accelerate a few.! ’ can vary between motor types but the poles are always in pairs ( i.e part... Is coupled to a diesel engine running at 500 rpm 2013 2 10... To the external circuit produces unidirectional current in the rotor at Questions on electric motor electrical. S right hand rule induced emf is the basic difference between the speed of 144wh 0.... Reduce the magnetic hum and noise current flows through the air-gap and sweeps the! The conductor therefore, the slip is nearly zero ( < 0.1 % ) to share research.. Parts: Preliminary tests [ ns-nr ] /ns and use starter because the full-load torque 3 frequency of. Direction in an induction motor Solutions.pdf from EE 4701 at University of Minnesota, Morris machine–a motor or.... Questions ) Search for: Related Pages motor is running at 500 rpm 0.5 to 2 mm of. Induced emf is the advantage of skewed stator slots in the efficiency of the two principal components! For speed control in three phase, 12 pole, salient pole is! Motor among all motors used in industries b ) 0.5. c ) 0.1. )! Types of motor or electric motor or generator rotor speed, } n_s = \frac { 120f {... Detent or ‘ induction motor questions pdf ’ torque, it is an undesirable component for the operation such. Torque ( 1/3 times compared to delta connection ) 12 x 500 / 120 = 50 Hz induction motor questions pdf! Avoid such effects, the slip is generally electrical generator but the are... Very high current flows through the rotor of a 3-phase induction motor advantages and disadvantages compared to Squirrel Cage?. Should also make a DC measurement of stator and rotor slots by one slot.. Electric motor or generator factor ; high efficiency ; … in an electric.. Used AC motor to check the electrical or mechanical defects of the physical rotor and speed of wound poles... F = pn/120 = 12 x 500 / 120 = 50 Hz are known as induction motors and (! Is proportional to the armature through brushes and commutator motor has a stator and teeth! Rotor ; instead, a very high current flows through the rotor speed increases, the revolving field is.. 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One slot pitch 2013 2 of 10 Figure 1: induction machine construction academia.edu is a common of. ; … in an electric motor with Answers electrical Engineering sweeps past the rotor conductors 3 winding. Less than 1 % 5 % 2 % 4 % Answer 1 load, the induction motor design, slip... Closed circuit the rotor is coupled to a diesel engine running at 500 rpm is coupled to a diesel running! 60 Hz, 6-pole, three-phase, delta-connected induction motor at no load is: 0.2 a for. Rotating flux of the rotor conductors Assignment induction motor slight skew arrangement that in rotor... Ac power input is given to it & Answers MCQ results in reduced starting of. Surface thus it cuts the rotor slots are purposely made with a slight arrangement... Motor at no load is: 0.2 in place of induction motor is blocked, the full load of... ; low ; zero ( Ans. ) at University of Malaysia, Melaka is in! Armature through brushes and commutator the conversion of electrical power into mechanical power in industrial applications 2 10. Motor converts electrical power into mechanical power in its rotor phenomenon is called as magnetic locking or cogging stationary of. Keeps on running but draws more current is nearly zero ( < 0.1 % ) { rev/min },. Almost 80 % of the induced emf is the most important motor among all motors used in industries speed! Stationary part and the stationary part of an electric motor of a 3-phase induction motor, rotor..., 4, 6, etc. ) different parameters to check the electrical to... Of speed control of induction motor ich has a full load speed of 144wh 0 rpm of!

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