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. S

    B Single phase induction motor Torque under increased frequency and Same Current

    Hi , Consider Single phase induction motor. What will be torque of induction motor, if we increase supply frequency 10 times, if the motor uses same supply current. Let's say Torque (Supply frequency 50 Hz, Supply current 10 Amperes ) = N What is Torque (Supply frequency 500 Hz, Supply...
  2. G

    Increasing induction motor frequency

    This is a question on a welding/machining forum. The OP has a lathe powered by a 6-pole (c.1000rpm) 3ph, 3hp, 50Hz, inverter-duty motor run in delta at 240V by a VFD capable of 400Hz output. Hobby use. The lathe is mechanically set to low speed, for maximum torque when parting off, etc. He...
  3. B

    What is the correct method for counting poles in a 3-phase induction motor?

    (I have modified the picture a little bit for clarity) Hi there! I had a chat with my colleague. He believes that the 3-phase induction motor on the picture below has 2-poles. There are 12 slots. Each phase contain 2 coils. I have showed how the coils are connected for the phase W at the...
  4. A

    Induction motor rotor design features

    I had to repair (change bearings) on a single phase induction motor recently and I recalled an age old question I've had. What are the rotor end ring blades made for ? The only reasonable answer I can come up with is - they are for cooling of the stator winding ends that extend out of the...
  5. Pipsqueakalchemist

    DC motors and Induction motor: What does "no load conditions" mean?

    TL;DR Summary: So I'm just confused when the question asks me to solve for the no load speed of DC motors and induction motors. Does no load condition mean that the output torque (Tout) is zero? This is what I was assuming so far for both DC and induction motor. Is no load condition the same...
  6. M

    Engineering Induction motor calculation problems

    Given the following input parameters: Parameter Value Rs (Resistance through stator) 1.4 Ω Rr (Resistance through stator) 0.7 Ω Ls (stator inductance) = Lr (rotor inductance) 0.002 H xs = xr = 2*π*f*Ls 0.6283i Ω Lm(magnetic inductance) 0.01 H xm = 2*π*f*Lm 3.1415iΩ f (frequency)...
  7. M

    Engineering Calculating Power Losses in an AC Induction Motor

    Given the AC Induction (asynchronous motor) in 3 phases: Parameter Value Pn (Nominal Power) = Pmechanical (output power at the shaft) 5 kW = 5000W uls (Voltage through the stator line) 220 V fstator (stator frequency) 50 Hz p (Number of pole pairs) 2 LFe (Iron loss) = Lmechanical...
  8. Flash27

    I Building a Linear Induction Motor | Tips & Tricks

    I am currently trying to create a linear induction motor for fun and am having some trouble getting it to start oscillating or move at all. I am using this video as a reference... I am using 3D printed PLA as the structure for the copper to wind around, 26 GA Craftware USA copper wire, 5/8"...
  9. adamaero

    Engineering How to calculate rotor flux of the three phase squirrel cage induction motor?

    Three phase squirrel cage induction motor with given parameters (stator winding connected in delta) nominal power: Pn=22.4kW nominal stator voltage: Vsn=230V nominal stator current: Isn=39.5A nominal stator frequency: fsn=60Hz nominal speed: nn=1168min−1 number of pole pairs: 3 stator...
  10. B

    4 Pole Induction Motor Working Principle

    Hello, I am studying the working principle of an induction motor. The attachment below (link) is a portion from Stephen J. Chapman's textbook (page 160-169). He proved the theory of the rotating magnetic field so well for a 2-pole induction motor from 160 to 164. However, on page 166, the...
  11. G

    Engineering Induction motor no load magnetisation loss

    The study material says under 'Estimation of magnetising losses' :On no-load, the rotor current is very small and the slip almost zero. Therefore, R′2s is very high and virtually no current flows through the branch of the circuit containing R′2s. Consequently, the no-load current is virtually...
  12. S

    Repulsion induction motor question

    Hello everyone, I have an old Hobart A200 mixer that I've rebuilt and the problem is the agitator shaft is spinning twice the rated speed when the motor comes up to speed. It has a repulsive induction motor. Speed 1 starts at about the rated 60 rpm but spins at about 120 when at running speed...
  13. G

    Sizing the start capacitor for an induction motor

    A friend has a single phase, cap start induction motor with the following characteristics: V 240/250 A 2.6 Hp 1/3 Rpm 1435 @ 50Hz As for as I know it’s not fitted to a machine, but given the low hp rating I’d guess it’s for a drill press. So it would need only moderate to low starting torque...
  14. SalahAhmed03

    Modeling an Induction motor in ANSYS Maxwell 2D

    Hii Friends. I was trying to model an Induction motor in ANSYS Maxwell 2D. The final output of Transient torque (negative torque) looks like shown below. The input passed is a sine wave current with 120 deg phase shift. Any Suggestion will be highly appreciated
  15. E

    Why can't a 2 pole ac induction motor run a 6 pole induction generator

    I will use examples of actual products: 1) 3 hp (2.2kW) 3 phase 2 pole AC Induction Motor 3 hp/2.2kW three-phase induction motor features 2 poles, 2840rpm rated speed, and 7.4Nm nominal torque, with a working voltage of 380V 50Hz. Cheap 3-phase asynchronous motor has outstanding performance in...
  16. PainterGuy

    Induction motor and Lenz's law

    Hi, The shown below, Figure 1, is an interaction of magnetic fields of stator and rotor of a squirrel cage induction motor. I believe the current is coming out of the squirrel cage bar on the left and entering on the right as is shown below, Figure 2. I have assumed that the bars highlighted in...
  17. C

    Engineering Understanding Windage/Friction Losses in Induction Motors

    So I've attached my graph and found that the windage/friction losses occur roughly around 230Watts. I just don't know how i further explain the magnetising current I0. I know I0 = input current on no load. So do i assumed from P = √3 x VL x IL x CosФ that CosФ=230/√3*220*6.8= 0.0849 or...
  18. A

    AC Induction motor startup current

    Friend gave me this task he had back in school to calculate the necessary amperage for a fuse that is put in series with one of the phases for a 3 phase induction motor. I could calculate the working current of the motor from the rated kW and cos voltage/current angle, but I couldn't figure out...
  19. D

    Citation for origins of the Kloss formula

    The Kloss formula (from Dr. Max Kloss) is apparently widely used in Europe and Russia to approximate the relation between slip and motor torque in a squirrel cage induction motor, but I've never seen it in an American paper or book. Does anyone have a source citation for this?
  20. cnh1995

    Wrong answer key for this Induction Motor question?

    So this question was asked in GATE-2019 (EE). (GATE is the national Engineering post-graduate entrance exam in India and is conducted every year by one of the 7 top IITs (Indian Institute of Technology) and IISc Bangalore. This year, it was conducted by IIT Madras.) The answer I found in the...
  21. J

    Mathematical model of an induction motor

    A coil is modeled as Z = jwL or Z = sL or V = L dI/dt What are the equations for an induction motor? Single-phase one.
  22. S

    Induction Motor Auto-Transformer Starter - Power and Torque

    Homework Statement Describe an auto-transformer starter. From the expression for power input per phase (∝ torque) show that for a turns ratio (n) of √3:1 , for the auto-transformer: Homework Equations Pin (phase) = 3 V I cos∅ I = V/Z cos∅ = R/Z T∝I∧2 T∝V∧2 For auto transformer with...
  23. L

    Engineering How Does Reducing Excitation Affect a Synchronous Induction Motor's Performance?

    Homework Statement (i) A star-connected, three-phase synchronous induction motor takes a current of 10 amps from a 415 volt supply at unity power factor when supplying a steady load. If the synchronous reactance is 5 ohms/phase and the resistance is negligible, draw the phasor diagram and...
  24. A

    Induction Motor to Stepper Motor

    Can induction motor be used as a stepper motor ?
  25. Z

    Finding the Torque vs RPM curve for a 3-phase AC induction motor

    Dear community, For one of the projects which I am currently working on, I want to quantify my three phase AC induction motor in the following ways: 1. Find Torque vs RPM Curve 2.Find Efficiency vs RPM Curve Now since I don't have the industrial "Torque Sensor" to plot Torque vs RPM curves, I...
  26. rishi kesh

    Engineering Resultant magnetic flux in a 3-phase induction motor

    Homework Statement I have some attachements below from my textbook. According to it the value of resultant flux is constant in magnitude and 1.5 times the maximum value of flux. But i have a doubt regarding how it is proved. The magnetic flux waveforms are 120° apart from each other and at...
  27. J

    Engineering Single Phase Induction Motor -- 2 Questions

    Homework Statement Question 2 Homework Equations Flux time lag depends on L/R ratio. More resistance, less time lag. Single Phase IM---Double Revolving field theory The Attempt at a Solution For 1st question, I think answer should be A. BB circuit has more resistance so BB Flux will have...
  28. R

    Ansys Maxwell- Transient torque fluctuating problem

    Hii Friends, I was trying to model an Induction motor 5 KW in ANSYS Maxwell. The final output of Transient torque looks like shown below. It fluctuates with average torque almost equal to zero Nm. The input passed is a sine wave current with 120 deg phase shift. Any Suggestion will be highly...
  29. F

    Induction motor - calculating rotor flux angle

    Hello. I'm trying to write my own soft for Field Oriented Control of induction motor. I have finished hardware - 3ph 3kW inverter, controlled by STM32F4, and V/F open loop algorithm to control ACIM - it works. Now I'm trying to implement FOC algorithm. As we know we need to do Clark&Park...
  30. Noaha

    Rotor and stator flux in 3 phase Induction motor

    The rotor and stator flux speed are stationary with respect to each other in 3 phase induction motor. What will happen if there is relative speed between them? How these two fluxes interact with each other to develop a torque?
  31. B

    WEG IE4 induction motor design

    Hello, is there anyone who knows how WEG managed to get IE4 efficiency rating for their motors while keeping Aluminum for cage on rotor? http://ecatalog.weg.net/tec_cat/tech_motor_sel_web.asp# Best regards
  32. T

    VSD for induction motor maximum current

    Hi, I'm trying to ascertain when you're driving an asynchronous motor with VVVF or whatever else a VSD uses, when do you draw the most current? For instance, say you're talking about a train/tram: I would have thought intuitively that since power = torque / angular speed, that starting up, to...
  33. Vikas Kasireddy

    Single Phase Induction motor winding phase difference

    Q1: So I'm trying to extract the electrical properties of a single phase induction motor. First off, how am I supposed to measure the phase difference between the start and run windings? I have L and R of start and run windings too! Q2: I have a torque vs slip curve up until 130% of rated load...
  34. cnh1995

    Zero sequence braking of induction motor

    I recently read about zero sequence braking of induction motor. In zero sequence braking of induction motor, the stator phases are connected in series and a single phase ac supply is connected across the series combination. Thus, the currents in all three phases are co-phasal, which are called...
  35. R

    Calculating Poles in a 3-Phase Induction Motor

    how many poles does 3 phase, 60 hertz induction motor which runs at 715 r/min at no load and at 670 r/min at full load have and how is it calculated?
  36. Z

    Engineering How Do You Calculate Current and Power Factor in a Synchronous Induction Motor?

    Homework Statement A star-connected, three-phase synchronous induction motor takes a current of 10 amps from a 415 volt supply at unity power factor when supplying a steady load. If the synchronous reactance is 5 ohms/phase and the resistance is negligible, draw the phasor diagram and...
  37. O

    Is 1MW 6kV 1600 RPM Motor Really Worth Only 40 Euros?

    Hi... Need help understanding 1MW, 6kV, 1600 RPM,Cage Rotor Asynchronous Motor, 3 Phase, 4 Poles. I have the basic understanding of all ratings but have received very low price for this motor but when i searched on the internet it looked huge and had very high price as compared to what i have...
  38. T

    Design choices for running an Electric train (and network)?

    Hi, I'm going to pose my questions with a number of assumptions, so please pick me up on any that are wrong. I want to know the design choices behind electric trains historically and current, this will mostly require some context of induction motors and inverters. I don't know exactly how EMUs...
  39. T

    Is DC More Efficient for Long-Distance Train Power Transmission?

    Hi I thought I remember reading that transmitting power over 800km's is passed the break even point for DC vs AC. And I read that modern rail is starting to use 25KV AC, but aren't many networks bigger than that, specifically in NSW Australia, the according to wikipedia it's 815km, I'm not sure...
  40. T

    Engineering Induction Motor Problem, How to find Rc

    Homework Statement A three phase 220 V , 60 Hz, six poles 10 hp induction motor has the following circuit. Parameters on a per basis referred to the stator: Rs = 0.334 Ω, R’R = 0.147 Ω, Xs = 0.498 Ω X’R = 0.224 Ω , Xm = 12.6 Ω The rotational losses including the core losses amount to 262 W...
  41. cnh1995

    Understanding Synchronous Rotation in 3-Phase Induction Motors

    Suppose a 3-phase IM is operating on a 50Hz power supply. When the motor is loaded, more current is drawn from the stator because of the demagnetizing effect of the rotor current. But the rotor current has a lower frequency i.e. slip*stator frequency. Still the reflected current in the stator is...
  42. DjMadness

    Power Factor Correction for a small 60W AC Induction motor

    Hello, I have a light AC fan, that I wish to correct its power factor. According to my measurements, it has around 0.7 LAG power factor. Here are my digital measurements: Vsupply = 204VAC I(load) = 0.237Amps phi = 43 , pf = 0.7 LAG My target power factor (pf) is to be 0.85 , and to...
  43. T

    Induction motor locked rotor test

    For the locked rotor test I have these values, P1 = 620W Stator line voltage = 32V Stator line current = 8.4A To calculate active power/phase, Po = (P1+P2)/3 But I don't have P2, Is P1 maybe equal to P2 ?
  44. R

    Induction Motor Builds & Experiments: What PSU to Use?

    So if you wanted to do some induction motor builds and experiments, what PSU would you use. I guess I am looking for a bench top AC multi output system that has ability to supply out of phase 2nds and maybe 3rd??
  45. L

    Equivalent circuit of an Induction Motor

    Hi, I have attached two circuits of an induction motor, one for steady state(1st circuit) and a dynamic model(2nd circuit). My question is: Why don't we include the induced emf in the steady state circuit? Looking at the dynamic circuit we include it, but not in the steady state circuit. Is the...
  46. srinaath

    Why slip is more in low HP induction motor?

    am doing a comparative study of induction motors (both single and three phase) based on cost, size, efficiency,etc... while analyzing 1/4Hp and 5 HP motors, i read that 1/4HP motor has high slip than 5HP motor because 1/4HP motor has greater rotor winding resistance than 5HP...so efficiency is...
  47. srinaath

    Why efficiency of induction motor is low for low HP?

    why there is a decrease in efficiency of induction motor when power rating is low? example 1 HP motor efficiency is say 85% then 1/4HP motor efficiency is less than 85%? please clear me this doubt?
  48. B

    Induction motor control by DTC method

    I´m simulating an induction motor control using DTC (direct torque control). I want to tune my PI controller to achieve a fast start up, but I don't have a transfer function to make an analysis. How can I set this controller?
  49. srinaath

    Cost of three phase and single phase induction motor

    hi guys... which will be costlier-single phase induction machine or three phase induction machine for same power rating, same rpm speed, same input voltage and current.?