Induction motors Definition and 27 Threads

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. Wrichik Basu

    Can RCCB trigger falsely when it is in line with induction motors?

    We have a sanctioned load of 63 A from the electricity supply company (AC RMS 230 V in my country). We have, however, not yet been able to upgrade our 45 A main fuse. Due to this constraint, we cannot run more than one high-current-drawing appliance simultaneously, like two air conditioners or...
  2. P

    Using Monopods for city travel utilizing linear induction motors

    This is another open ended question, exploring a space of design concepts, in similar spirit to this. I want to explore monopods with regard to travel in densely populated cities(even possibly intercity travel). The main idea is to use small personalized pods to travel in tubes(or tracks). The...
  3. 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...
  4. Mathew Joseph

    How to make the power factor of induction motors be a leading power factor?

    Hi guys, This month onwards our power distributor says that we only get powerfactor incentive when only we make the powerfactor leading and in between 0.95 and 1. Our industry fully consists of induction motor and compensative capacitors are provided but this month onwards we have to keep the...
  5. G

    Induction Motors: Rotating Magnetic Field & AC Frequency

    Hi, Can I please ask how the rotating magnetic field (due to the 3 phase ac) is changed? Is it due to the frequency of the ac supply that it can speed up and therefore drag the rotor along due to induction. If it is due to the changing frequency input that mimics a faster rotating magnetic field...
  6. Osvaldo

    Understanding magnetic balance in AC induction motors

    I need to find out how calculate magnetic forces appearing in AC induction motor rotor when it is not magnetically centered inside the stator.
  7. R

    Determine the sum of the windage and friction losses for this motor

    Hi I was wondering if someone could tell me the equation for finding out what the windage and friction losses are based on the information below. I've drawn the graph and I can work out the I/0, R0 and X0A four-pole, star-connected, squirrel-cage induction motor operates froma variable voltage...
  8. P

    Exploring Tesla's Autos & Induction Motors

    As a EE student, I studied Induction motors: three and single phase. I saw somewhere that Tesla's autos are using induction motors feeded by batteries. But I've never heard about DC induction motors.. I also heard that Tesla autos have torque constant for every speed, but that's also not how...
  9. shina

    Electricity and the operation of induction motors

    How electricity passing through a conductor produces magnetic field around it. How an induction motor works. The energy or electricity which passes trough green earthing wire is transmitted into the ground. Why this energy is not conserved and can be used in future. All these three things are...
  10. G

    Induction motors and power factor

    Hi all, I have a 1 HP capacitor start motor (old, c.1950) that runs an air compressor in my little workshop. When it's running, the lights in the shop and the whole house dim and brighten rhythmically, at about 5 Hz. This, of course, is related to the compression cycles of the compressor, but...
  11. srinaath

    Why single phase induction motors are used for fractional HP applications

    why single phase induction motor is commonly used for low HP rather than integral HP like 1,2,3HP... i understand that single phase gives low power...but say you have designed such that your motor delivers 10HP for rated voltage and current...why such single phase machines are not common?can...
  12. cnh1995

    Cascade connection of induction motors

    In cumulative cascade connection of two induction motors, why does the net speed reduce? Also, how are the torques of the two motors in the same direction?
  13. B

    How Can I Determine the Number of Poles in a Burnt AC Induction Motor?

    Hello, I want to know determining the number of poles by inspecting coils inside the motor. Generally, there are formulas allowing us to plug a frequency, an rpm, and give off the number of poles, or we can just simply look at its nameplate. My reason for needing the inspecting is that my...
  14. D

    Electric machines (looking for books)

    Please help me, this is my last hope. I am an el. engineer student and i need GOOD books on electrical machinery. My proffesor is more a good repairman than a great scientist who could teach me about all the theoretical (matematical and physical) concepts which have led to modern design process...
  15. 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...
  16. ranju

    Finding Full Load Current & Torque in Induction Motors

    In an induction motor problem , I need to find the full load current & torque..for that I calculated the impedance with given data..& I got the impedance in polar form..But in the solution for finding the full load current they put only the magnitude of the impedance & not the phase..! I didn't...
  17. T

    What is the required torque for a spinning flywheel?

    Hello, I would like to know the amount of torque required when the flywheel starts? I know that once at speed the flywheel doesn't require torque. I would also like to know what size of slip ring induction motor to run as the below mentioned speed. The weight of the flywheel is= 6500 kg ( wt...
  18. W

    Squirrel cage induction motors - rotor issues

    Hello all, I am currently involved in a diagnostic project for an induction motor with suspected rotor stator contact. all critical dimensions have been checked but the question has been raised by none electrical observers: Does the location of the rotor bars effect the magnetic center line...
  19. N

    Understanding Rotor RMF in Squirrel Cage & Slip Ring Induction Motors

    is the rotor rotating magnetic field(R-RMF) present in squirrel cage induction motor (SCIM). Is it same as in 3 phase ROTOR winding of slip ring induction motor (SRIM), generating rotor RMF. * THE 3 phase, supply given to stator 3 phase winding of SRIM, generates (RMF), which cuts the rotor 3...
  20. T

    Does amperage matter in induction motors?

    if i increase the amperage in an induction motor, will the induction motor spin faster? and vise versa?
  21. B

    Induction Motors: Power Consumed vs Power Delivered

    Hello The equation for power consumption of a three phase induction motor is given by the equation: P = sqrt(3)*V*I*(PF) Does this differ from the power that is delivered to the motor. For example, if a motor is running at 460 volts, 30 amps with a PF of 0.82, then the power...
  22. M

    V/f speed control of 3 phase Induction motors

    When the voltage / frequency is maintained constant in 3 phase Induction motor i.e. flux is maintained constant by changing the voltage and frequency in same proportion, What is the torque proportionality equation. Whether Torque is proportional to Slip X Frequency or Torque is...
  23. M

    Engineering Induction Motors, Generators, Magnetic Field Strength, Force and Coupling

    Homework Statement Here are a bunch of questions that I've attempted. I feel fairly confident with my answers, but I just wanted to make sure :) Thanks! a) calculate the synchronous speed, amount of slip and the percentage slip in a typical aircraft a.c., four pole, 400hz induction motor...
  24. V

    Single phase induction motors (cap run)

    I understand there are different types of induction motors. We use single phase 2 pole and 4 pole cap run motors which have a pretty good balance between forward and reverse torque. We are able to get motors where they adjust the coils to get the forward and reverse toque to be different, up...
  25. H

    Understanding Induction Motors & Reactive Power

    I was reading about induction motors and speed controller(self commutated inverters for cage motor), and i didn't understand this sentence:"The induction motor can either absorb or deliver reactive power". Thanks for any help.
  26. A

    How Efficient and Effective Are Typical Three Phase Induction Motors?

    hey does anyone know the effiency and power factor of a typical three phase induction motor? cheers,
  27. M

    Induction Motor EE Problem: Get Correct Answer Now!

    Hi I need Help with an EE problem I have tried doing it like 10 times but i keep on getting the wrong answer can anyone help me here it is Below is the equivalent circuit model for an induction motor. THe resistance on the right (0.1/s) charges with motor speed. S stands for slip where Zero...
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