What is Induction motor: Definition and 137 Discussions

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. An induction motor can therefore be made without electrical connections to the rotor. An induction motor's rotor can be either wound type or squirrel-cage type.
Three-phase squirrel-cage induction motors are widely used as industrial drives because they are self-starting, reliable and economical. Single-phase induction motors are used extensively for smaller loads, such as household appliances like fans. Although traditionally used in fixed-speed service, induction motors are increasingly being used with variable-frequency drives (VFD) in variable-speed service. VFDs offer especially important energy savings opportunities for existing and prospective induction motors in variable-torque centrifugal fan, pump and compressor load applications. Squirrel-cage induction motors are very widely used in both fixed-speed and variable-frequency drive applications.

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  1. srinaath

    Driving three phase induction motor with single phase supply

    hi guys, am working on variable speed drive system. My aim is to make a low cost drive system for three phase induction motor. Current system employs three phase AC-DC and DC-AC converters, which has 12 switches in total. I have one idea...i found three phase inverter topology which has 4...
  2. T

    Clean way to run 3 phase induction motor

    Say you wanted to run an induction motor from a battery without putting dirty harmonics into it. Would a really clean way to do it, to be by using a higher phase number inverter, then transformer, then into the motor? For instance, a 6 phase inverter, into a 6 phase to 3 phase transformer, then...
  3. J

    Equivalent Circuit for a CSCR Single Phase Induction Motor

    I have created a circuit diagram for a single phase CSCR induction motor, but only for the purpose of calculating start-up current (i.e. motor speed is at, or very near, zero RPM). I have created this diagram because: 1) I do not have the tools & knowledge required to generate the Steinmetz...
  4. ranju

    Engineering What is the role of rotor bars in single phase induction motors?

    Homework Statement I studied that as the single phase motor speeds up the backward induced field currents are larger than the forward field currents. So , the corresponding opposing rotor mmf causes backward field to be greatly reduced whereas the smaller forward currents leads to enhancement...
  5. cnh1995

    Rotor EMF in squirrel cage induction motor

    In a 3 phase induction motor,when stator rmf rotates, it cuts the rotor bars and induces an emf in them. Is this emf sinusoidal? I mean shouldn't it be a square wave since the rotor "bars" are being cut by the flux, like in case of concentrated stator windings of a synchronous generator? If the...
  6. J

    Engineering Magnetising circuit parameters in a 3ph induction motor

    Homework Statement Homework EquationsThe Attempt at a Solution Stator Line voltage 220 164 112 88 42 Stator Line Current 6.8 5.4 3.9 3.8 3.7 Stator power 470 360 278 244 232 By plotting a suitable graph from these results, determine the total of windage and friction...
  7. J

    Electrical reason for big air gap of induction motor

    in induction motor there is air gap between stator and rotor. the air gap needs to be as small as possible. but some air gap is needed for mechancial reasons. i understand that a big air gap would reduce power factor as you'd need more magnetizing current. but are there any advantages of big...
  8. cnh1995

    Why Does Torque Increase as Slip Decreases in a Single Phase Induction Motor?

    Single phase motor is not self starting, so it is started using some arrangement and the starting arrangement is disconnected(not always) once the motor is set in proper motion(about 70% of the maximum speed). But I didn't understand this graph. From the starting moment, motor accelerates and...
  9. T

    What Happens to Flux in an Induction Motor When Short Circuited?

    Just a curiosity about what happens to the flux, when you short circuit an induction machine. Say there is an initial flux and you're rotating the shaft of an IM and then you short circuit the stator, so no doubt you'll get large currents in the stator, but those large currents, will they cause...
  10. cnh1995

    Understanding the Formation of 4 Poles in an Induction Motor

    I've studied a 2-pole IM with its winding diagram and understood how the two poles are formed. But I'm struggling to understand the same thing about a 4-pole motor. How does this winding arrangement result into 4 poles?
  11. C

    Engineering Induction motor torque formula

    I am learning basic motor control and there is a formula list in my book. The last one is for torque calculation, can anyone point out to me where this one is from or how is it derived?
  12. Z

    Why does q-axis stator current control torque in 3-ph IM?

    I know that decoupling the 3 phase currents we get the id and iq (in rotor frame) currents which control the flux and torque respectively. But where does the relation come from?
  13. C

    Induction motor vector control stator current vector

    I am new to flux oriented control and i read that this method is to decouple the stator current, one component for flux producing and other for torque,so that so that we can control these two current components to control an AC motor like a DC one(right?) However when i try to dig into detail...
  14. Z

    Flux is not controllable in Direct Torque Control of IM

    Hi all, I was trying to simulate a direct torque and flux controlled induction motor in simulink. Even though I've managed to control torque within the band, i can't seem to be able to control the flux. It stays for a while within its hysteresis band and escapes after about 0.1 sec and keeps on...
  15. L

    Why does a 90° phase shift maximize induction motor torque?

    Capacitor-start induction motors use a capacitor in series with the start winding to create torque to start the motor. After the motor gets nearly up to full speed, a switch takes the capacitor out of the circuit. I understand the torque is caused by the phase shift created by having the...
  16. cnh1995

    Induction motor as transformer

    It is observed that the stator current of IM increases on loading. In transformers, the increase in primary current due to loading is significant . Is it same in induction motor? Does the air gap affect it?
  17. D

    Hello Everyone....Single phase induction motor design

    is there anyone who knows a company that can design single phase induction motor prototypes in the UK..Thanks for your help
  18. T

    Induction motor equations question

    Homework Statement I came across these two equations in a chapter on induction motors, and I was wondering if they both calculate the same thing? ##w_r=sw_s## ##w_r=w_s - \frac{p}{2}w## Homework Equations The Attempt at a Solution s is the slip, ##w_r## and ##w_s## are the rotor and...
  19. S

    How Many Turns are Required for an Induction Motor in Different Voltage Levels?

    I want to known the stator design of an indiction motor. How may turns required for each pole. For exmple if a single phase motors is designed to run at 230v ac, how may turns required in each pole. If the same motor is designed to be run in lower voltage (say 110v ac or 12v ac) what will be the...
  20. AlexiaIoannou

    How to design a single phase induction motor

    Hi everyone... I have to design a single phase induction motor. I have some questions and it would be great if you could help me. The parameters I have for the design of the motor are: rated power, rated voltage, frequency, rated speed, power factor, efficiency, full load current and full load...
  21. A

    Clarke-Park transform for an induction motor current

    Hi everyone, I am facing some problems in performing clarke-park transform for an induction motor(4 pole stator, squirrel cage IM). The motor is run with three sine wave inputs, 120 degrees phase shifted with each other. I am measuring the rotor position from the encoder and using twice of...
  22. N

    Why crawling happens in induction motor?

    It is said that crawling occurs mainly due to 7th harmonic component. Due to 7th harmonic the speed decreases by the ratio of 7. However speed is directly proportional to frequency. So speed should get multiplied by a factor of 7 instead. Should the change in frequency affect the number of poles...
  23. P

    3 Phase Induction Motor Full Load Power Factor

    Hi, If the voltage, full load current and full load output power (kW) of a 3 phase induction motor are known, and the efficiency is assumed to be 90% (is this realistic), am I correct in thinking that the full load power factor can be approximated (due to assumed and not actual efficiency) as...
  24. A

    Three phase induction motor efficiency

    Hi, Is there a difference in efficiency between a three phase motor and a single phase motor, in terms of power in against power out. If so, could you please explain why one is more efficient than the other. The reason I ask is because I'm researching the development of the induction motor for...
  25. H

    Induction motor generator capacitor

    Hope I can get some help here. I have a 1-1/2 hp. 115/230 volt single phase induction motor I want to use as a small generator. currently it's wired for 115 volt I need help with the math to calculate the proper capacitor/s to use. Running no load amps as a motor draws 18 amps. Name plate...
  26. M

    Single phase Induction motor Design

    I want to design a single phase induction motor (1/3 HP,50Hz,220V). I face a problem to design the main dimension of stator and Slot shape and Rotor skew angle . Would you give some idea for design ? or any related book and software ?
  27. C

    Three phase Induction Motor torque/slip HELP NEEDED

    Hi, I'm really stuck on this assignment question and could do with a hand on the step by step process of how to get the answers. A three phase induction motor as 2 poles, a standstill voltage of 121 v/phase (Er), rotor resistance of 0.15Ω/phase (Rr) and a standstill rotor reactance of...
  28. H

    Induction motor and sequence reactance

    Hello! This is my second post about sequence reactances. This time- its in induction motor. To my understanding ( once again ) - In any network (symmetrical or unsymmetrical) , there would be 3 components- positive sequence component, negative sequence component and zero sequence...
  29. S

    Engineering How Do You Calculate Torque and Efficiency in a Three Phase Induction Motor?

    Homework Statement A three phase cage rotor induction motor running at full load draws a stator current of 60A at a power factor of 0.8 lagging from a 415v, 50Hz Supply. Under the conditions the stator loss is 3.6kW, the rotor loss is 1.3kw and percentage slip is 4.5%. If the shaft power...
  30. G

    Does decreasing input voltage affect the slip in an induction motor?

    Hello all My question is: Induction motor with nominal load rotates with nominal speed. How the slip will be changed if we decrease input voltage in 10%? I think that if we decrease the voltage, than the current will be decreased also. Than, the moment will be decreased and mechanical...
  31. R

    Engineering Characteristics in three-phase induction motor

    Homework Statement I can not understand this question: "Describe the characteristics of a three-phase induction motor?" Does it mean speed,torque,etc? Thanks Homework Equations The Attempt at a Solution
  32. P

    Induction Motor Torque Decreasing when Load is increased

    Hi. Having measured an induction motor on no load and obtained a torque figure, I have noticed that when load is increased, the torque continues to decrease. How it this possible as I am observing a reduction in rotor speed and increase in rotor currents and current drawn from supply?
  33. P

    Induction Motor Slip decrease with frequency decrease for same load.

    Hi, Does anyone know or could help me understand the reasoning for the amount of slip within an induction motor decreasing with frequency under the same load conditions? I.e. For no external load, the slip is higher at 50Hz than at 20Hz etc? Thanks
  34. P

    Induction Motor Query: Current, Power, Torque & Speed

    Hi, I am currently simulating a 3 phase induction motor system. One of the tests that I have run is to keep the motor parameters (reactance, resistance etc.) constant, and then change the frequency of the supply (50, 40, 30 Hz etc.) before measuring input parameters (current and power drawn...
  35. P

    Induction motor rotor and stator fluxes

    Hi, When a load is applied to the rotor of an induction motor, the rotor speed decreases and as a result, the induced currents in the rotor and the torque produced increases due to the relative speed difference between the rotor and the rotating field within the stator. My question is...
  36. T

    Induction Motor Speed: Electrical vs Mechanical

    Hello Everybody, Can anyone explain, what is thee difference between 'electrical spped' and 'mechanical speed' of rotor in an induction motor? what do they signify? Many literatures say that electrical speed is no of pole pairs times mechanical speed, if somebody can explain... Thanks
  37. O

    Calculating Frequency for Induction Motors with Given Horsepower and Pole Count

    Hello I'm doing a question in induction motor now. formula for Induced torque is Pgap / Ws. i have found the Pgap, but in order to find Ws, i need frequency to find ns.. so my question is, how to find frequency with only given 10hp and four pole
  38. S

    Induction motor project advice

    I'm planning on building a simple induction motor for my class project and am hoping someone might have some advice about powering the motor. I feel a little ridiculous asking but I had almost no understanding of electricity prior to the beginning of my Physics 212 class and the textbook doesn't...
  39. M

    Engineering Speed control of induction motor in steady state

    In this experiment, we'd learn about vector control of an induction motor. By using the constant rotor flux linkage vector control method, An AC induction motor can achieve a DC motor-like performance. Firstly, we tested on speed control response in steady state. *the proportional gain kp =...
  40. K

    [Induction Motor] help to understand this concept

    Hi all I am trying to understand the concept of 3 phase wound rotor induction motor. I understand why when you feed in 3 phase current to the stators that are separate spatially 120 degree will get you a rotating magnetic field. However, I am having much trouble in understanding the...
  41. M

    Engineering Inverter - V/F constant control of an induction motor

    Hi. I am writing a report on an experiment. The experiment is on power electronics. An investigation of V /f constant control of induction motor with inverter was carried out. A converter and an inverter are connected to an induction motor to change AC to DC and back to AC, as shown in the...
  42. M

    Engineering V / F constant control of induction motor with inverter

    Hello. I have to do an experiment on this topic, but there are many things I don't know. First of all, can you tell me what do the symbols V~ and A~ mean?
  43. M

    Operating principle of a Six Phase induction motor

    Hi Sir, I have seen in many IEEE magazines that, a six phase induction motor is having two 3 phase windings spatially separated by an angle of 30 degrees electrical. I have attached the 6 phase induction motor diagram. But I am not able to understand how the motor operates i.e. how the rotor...
  44. J

    Engineering P= 1.732 X 230V X 42A X 0.85 = 10,731.06 W or 10.73 kW

    3 PHASE INDUCTION MOTOR A 15 hp/230V, three phase induction motor has a full load current of 42A per terminal. 15HP= 11kW find: a) Full load kVA input b) If the full load power factor is lagging 0.85, what is the kW input. My question: How do I know whether its connected Wye or Delta?a) kVA=...
  45. E

    Volts/hertz control of three phase induction motor.

    I am doing project on open loop v/f control of three phase induction motor. How to decide the frequency and amplitude of triangular wave(carrier wave) for sinusoidal PWM ?
  46. B

    Induction motor load estimation from a variable resistive load

    Hello, I'm trying to find out how much energy an induction motor pulls over a 24 hour period when connected to a resistive load. The only data I have are the specifcations of the motor, so I can estimate how much energy it will draw based on what capacity it might be running at. Really...
  47. M

    Induction motor - no load speed

    Under no load, does an induction motor run exactly at its synchronous speed (i.e. relative field speed) or at a speed that is close to the synchronous speed but slightly less? Thanks for your time.
  48. P

    Engineering Calculating Slip and Number of Poles in Induction Motor

    an 8 pole 3 phase alternator is coupled to a prime mover running at 750 rpm.it supplies an induction motor which has a full load of 960rpm find the number of poles of the motor and the slip i think the induction motor would work as a generator we can find slip by usin s=(ns-nm)/ns where...
  49. EVriderDK

    Ok, but WHY does the asynchronous AC induction motor have an unstable zone?

    I have been tought several times that if an asynchronous induction motor is overloaded, so that the rotor speed goes below where the maximum torque point is, the motor will become unstable, and simply stall, even if you unload it. Why does it do that? fx. here...
  50. W

    How to calculate reactive power for 3 phase induction motor

    Hi all, I would like to install Capacitor Bank into my control panel board which contains of few 10HP induction motors. Currently I'm just able to measure the Ampere for every induction motor by using current meter. How to calculate the reactive power for 10HP 3phase 4pole induction motor by...
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