Electric motor Definition and 222 Threads

An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate force in the form of torque applied on the motor's shaft. Electric motors can be powered by direct current (DC) sources, such as from batteries, or rectifiers, or by alternating current (AC) sources, such as a power grid, inverters or electrical generators. An electric generator is mechanically identical to an electric motor, but operates with a reversed flow of power, converting mechanical energy into electrical energy.
Electric motors may be classified by considerations such as power source type, internal construction, application and type of motion output. In addition to AC versus DC types, motors may be brushed or brushless, may be of various phase (see single-phase, two-phase, or three-phase), and may be either air-cooled or liquid-cooled. General-purpose motors with standard dimensions and characteristics provide convenient mechanical power for industrial use. The largest electric motors are used for ship propulsion, pipeline compression and pumped-storage applications with ratings reaching 100 megawatts. Electric motors are found in industrial fans, blowers and pumps, machine tools, household appliances, power tools and disk drives. Small motors may be found in electric watches. In certain applications, such as in regenerative braking with traction motors, electric motors can be used in reverse as generators to recover energy that might otherwise be lost as heat and friction.
Electric motors produce linear or rotary force (torque) intended to propel some external mechanism, such as a fan or an elevator. An electric motor is generally designed for continuous rotation, or for linear movement over a significant distance compared to its size. Magnetic solenoids are also transducers that convert electrical power to mechanical motion, but can produce motion over only a limited distance.
Electric motors are much more efficient than the other prime mover used in industry and transportation, the internal combustion engine (ICE); electric motors are typically over 95% efficient while ICEs are well below 50%. They are also lightweight, physically smaller, are mechanically simpler and cheaper to build, can provide instant and consistent torque at any speed, can run on electricity generated by renewable sources and do not exhaust carbon into the atmosphere. For these reasons electric motors are replacing internal combustion in transportation and industry, although their use in vehicles is currently limited by the high cost and weight of batteries that can give sufficient range between charges.

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  1. P

    Load on an electric motor vs. current draw

    According to classical physics, if I take an electric motor with a resistance of 1 ohm, and run 10 volts through it, 10 amps of current will run through it. But through experiment, a lot less current will run through the motor, an average brushless motor with a resistance of less than a milliohm...
  2. R

    Electric Motor Design? Learn How in EE School Classes

    I've been looking at the undergrad catalog of my school and I haven't noticed any classes that teach motor design. I found classes on drives and motor control but nothing on the actual design of motors/generators. I always thought electric machines was a fundamental topic that all EE curriculums...
  3. S

    Can I get a 40KN force from a hydraulic cylinder powered by an electric motor?

    Im thinking of designing a tipping trailer for a car. I need a force of 40KN exerted to tip but would this be too much for driving with an electric motor powered by the car battery. If not what size of motor and pump would I need? thanks
  4. X

    Engineering Understanding Electric Motor Coils and Direction: Exploring DC Motor Theory

    Homework Statement Why must the coil in an electric motor kit be wound in only one direction? Why must the current change direction every 180 degrees in the motor? Homework Equations No relevant equations. Just a simple answer. The Attempt at a Solution NI-Prentice Hall DC Motor...
  5. N

    Electric motor efficiency calculation

    Hello everyone, I am trying to calculate the electric efficiency of some 3 phase electric motors but I am a little confused about the power factor. efficiency=work out/work in work out=rated W of my motor (hp*745.7) work in= V*A*PF*√3 Is the work in correct? Thanks
  6. G

    Electric motor temperature sensor locations

    Hi guys, I'm trying to design a brushless motor for an EV with temperature sensing for both the copper coils in the stator and the permanent magnets in the rotor, but I'm not sure how to add a temperature sensor on the neodymium magnets in the rotor. Wouldn't the high levels of varying...
  7. T

    ME trying to find a proper electric motor any help would be appreciated.

    For a special project, a team and I are trying to create our own automatic golf ball tee setter. To make a long story short, I need a motor, but I've never purchased motors before, and my EE skills are pretty weak, so I need some help... Here are some specs that I need to meet: The motor...
  8. U

    Brushed DC Electric Motor Used as a Generator

    I was wondering whether there was any literature on brushed DC motors used as a generator or whether you know anything of the sort? I know that DC motors behave differently when used as a generator instead of a motor. However I have not been able to find anything about it so I was wondering...
  9. P

    Bigger copper windings make electric motor faster?

    I want to use some motors i had laying around to do a project. A flick of the shaft measures 5MA. I want to rewind the motor so it produces 10ma. do I use bigger wire, or the same size wire just more of? less of or will I just have to
  10. G

    Calculating Force and Torque on Electric Motor Coil

    Homework Statement An electric motor has a square coil with 20 turns and an area of 150cm^2. the coil is free to rorate in uniform magnetic field of 300mT. If there is a DC current of 5.00A, passing through the coil: what is the maximum force on one side of the coil? and what is the maximum...
  11. E

    What are the criteria for choosing a DC electric motor for a helicopter winch?

    Hello, I am designing a helicopter winch (basically, a drum to spool and retrieve a cable), and need to select a DC electric motor from some catalog. This motor needs to fit inside an cylinder of radius 165 mm and height of 200 cm or less. it has to be a Permanent Magnet (PM) engine. and...
  12. P

    Resistance of an electric motor

    Homework Statement An electric motor connected to a 120 V, 60 Hz supply does work at a rate of 0.1 hp (1 hp = 746 W). If it consumes an rms (root mean square) current of 650 mA, what is its resistance, in terms of power transmission? Would this result be the same thing as the resistance of its...
  13. A

    Understanding Electric Motor Rotation & Magnetic Field Vibrations

    ok, so i have drawn a diagram for 43 and i would like to know if i have done it correctly.. i believe the rotation should go the other way. Also can someone help me with the paragraph to wrtie about it and for the other question, does it have something to do with the magnetic field causing...
  14. R

    1P Electric Motor - L1 Constant Hot?

    Hi all, I'm in the process of rebuilding a land-based boat house that was leveled in a tornado. This is one of the old styles with the railroad tracks and a tram to hoist the boat in/out of the lake. The tram/winch motor has to be replaced. It is single phase 240V. As best I can tell, the...
  15. C

    What are the symbols in these electric motor equations?

    I'm revising for an exam and i’ve come across these equations in my lecture notes. Has anyone seen these equations before, and can tell me what the symbols represent? T = k1 ᶲ Ia Ea = k1ᶲ2πN = k2ᶲN Ea = Va-IaRa N = (Va-IaRa) / (2πk1ᶲ) Im guessing T is torque, Ea is the volatge across the...
  16. J

    Supplier for coaxial electric motor

    I'm designing a test fixture and need a compact coaxial electric motor. The motor drives two counter rotating fans with tip speeds up to 650 fps (desired), 500 fps (required). The fan diameter has not been selected, but is between 2 to 3 ft. Initial estimates suggest that the total fan...
  17. T

    Producing constant torque in the simple electric motor.

    In the simple electric motor, applying a constant current produces a pulsating torque. But if we apply a pulsating current will it produce a constant torque?
  18. P

    Basic single phase electric motor wiring help

    i have a 20 year old electric garage door motor that i cut out of the housing and kept but threw away the rest as garbage. now that i want to use the motor, i have no recollection of how the wiring worked. it is a very clean basic motor made by samsung. it's a 120 volt, 5 amp, single phase...
  19. C

    Increasing the efficiency of a simple electric motor?

    Okay, so I have a simple D cell battery, enamel coated copper wire loop and a magnet. I can easily get the copper wire loop to spin if I scratch away part of the enamel (that side which touches the stand) off the ends of the wire, run current through a stand, and position the magnet at just the...
  20. O

    Engineering Conductor inside an electric motor current calculation

    Homework Statement A 500 mm conductor inside an electric motor has a force of 1.5 Newtons exerted on it. If it is at right angles to a magnetic field of flux density 0.6 T, calculate the current flowing in the conductor. Homework Equations F=B.I.L The Attempt at a Solution B = 0.6T F =...
  21. J

    Electric Motor Question: Effects of Reverse Pulse at High Speeds on Coils"

    if you are spinning a large permanent magnet motor at high speeds and add a reverse pulse to the motor for use as a break does this wear or damage the coils in the long run? I was under the impression from what I know that it added heat and slowly wore on the wiring. Similar to holding the...
  22. H

    (QUESTION) electric motor nature

    ok, so I am coming from a complete automotive perspective so when i refer to voltage applied to an electric motor (engine starter motor for example) i mean 12v direct current. typically consisting of a battery that puts out 500 cranking amps.. the question is real simple but iv noticed auto...
  23. F

    Torque equation of an electric motor

    The example I am looking at in my textbook starts by considering and area of the rotor surface of width w and length L. Then the axial current flowing in the width w is equal to I=wA which is exposed to a radial flux density B So from the Lorentz force F=IBxL the equation becomes F=...
  24. Y

    Leeson Reversible Electric Motor - 1/3 HP, 1725 RPM

    hi .i am new here i like to know if this motor can't reversed using a switch from turning right to left . i am a knifes maker [was] and my motor have to turn clock wise and counter clock . thank you . yvesj
  25. C

    Gears, Pulleys, & Electric Motor Questions

    Hi all, brand new to the forums. I'm a student of chemistry so I am very unknowledgeable about mechanical engineering and need some help. Not asking for spoon-feeding. What I am trying to accomplish is fairly simple(I hope). I would like an electric DC motor to turn a 1in diameter teflon...
  26. M

    Required Electric Motor Torque For Sm Car

    I am trying to spec out a small dc motor for a shoebox sized car. If I have a motor with a gear on it rotating a second gear with a gear ratio of 1:1 that is attached to the axle with a wheel at each end, how can I calculate how much torque the motor needs to be capable of supplying to move...
  27. S

    Why is it difficult to find a small electric motor with 2000RPM and good torque?

    I've been looking on Mcmaster Carr and Digi-Key for a small electric motor. It needs to be a 2000RPM motor but also to produce a torque preferably greater than 1 N-m, but less than 1.6 N-m. The torque really can be anything though, i'd just like it to be greater than 1 N-m I'm having trouble...
  28. A

    How to use an Electric Motor to recharge a battery.

    Does anyone know how to use an electric motor to charge a DC battery? I read on ehow.com that all you need to do is find a way to spin the shaft and it produces electricity that will charge the battery? Is that true, is it that simple?
  29. T

    How fast would an electric motor spin in space?

    If you had an electric motor in space how fast would it spin since there is no friction? Would it build up to light speed?
  30. W

    Small electric motor that can be plugged into a car power adapter

    I am trying to find a small electric motor that be powered by plugging it into a car power adapter. I am trying to power a spinning shaft off of it that will need a fair amount of power. Meaning enough to spin a brush.
  31. S

    DC Electric Motor Tourque/Power Usage

    DC Electric Motor Torque/Power Usage Hello Everybody, I am mid way through doing an electronic engineering degree, I fancied as a summer project to build 6 wheel search and rescue robot. Idea being to use wheel chair motors to get the thing going. The problem is I am not an mechanical...
  32. K

    Choosing the Right Electric Motor for Your Mid-Size Car

    What type of electric motor would be best for installing in a Mid-size car? I have a design for installing an electric motor in a car with a generator to power the motor and batteries with an inverter for starting the motor. The motor once started will run at a minimum 400 rpm, then increase...
  33. D

    How different is an electric motor from an electric generator

    I recently bought a hand-crank phone charger. When I opened it up, it looks like the generator is simply a repurposed electric motor. I have not yet tried to flow current through it to see it if would spin. However, I wonder how similar a motor is to a generator. I have heard of electric cars...
  34. P

    How to size a generator needed for an electric motor

    I will buy an electric bicycle in a couple of months and want to modify it. I will install a motor that has a max rating of 6,000 watts - common use is about 3k watts. I am also looking for a small, lightweight gasoline engine to connect to another motor - to make a small generator - so that I...
  35. S

    What type of electric motor is beter?

    What type of electric motor is most compact and powerfull for its size (in 70 kW range)? Is there some hope that very powerful, compact, cheap, low voltage DC motor will be ever created?
  36. N

    Fixing High-Pitched Whirring Electric Motor Issue

    My electric kitchen-aid mixer recently began to make a high pitched whirring sound that increases in pitch with the speed of the motor. After disassembly and cleaning, all of the parts seem to be damage free and operational. Any ideas what could be causing the noise?
  37. T

    Power consumption of electric motor

    Hi everybody, I'm building a board game right now. The game consists of a train of gears that I would like to drive with an electric motor. The gear train can be many different sizes (# of gears) and patterns (size of gears). What I would like to do with the motor is measure the...
  38. P

    Finding the Right Electric Motor for My Pump Setup

    OK, here's my dilemma: I have a pump that requires 3600RPM, 24lb.ft. of torque (optimally) to run it. It was attached to a gasoline powered 16HP motor, and I need it to run off of an electric motor now. Not so difficult, you say? My only power supply is limited to 24VDC. I am looking for...
  39. S

    Slowing Down a 1/2hp Electric Motor for Hogs for the Cause

    I am in business school and every year we do a charity event called hogs for the cause (http://www.hogsforthecause.org/ ). This year we are planning on putting a pig on a spit and have designed the cooking apparatus. I have combed craigslist and found an electric motor that should be able to...
  40. V

    Stirling engine to electric motor

    Does anyone know what stirling engine could be used to power a generator which in turn powers an electric motor? I am thinking of using this concept in a vehicle. A diagram is here: It shows a metal sphere in vacuum sealed container. It would be connected to by a retractable contact...
  41. R

    How to test an small electric motor

    I hope this does not seem a trivial question. My car's window washer pump motor stopped working and I took it out to replace it. Being curious I did some tests before fitting a new one. First, the circuit fuse is intact and the electrical connector to the pump motor is delivering 12 V, as...
  42. T

    Engineering Derivation of normal and tangential forces of a rotor electric motor drives

    Hi all, I'm currently undergoing a masters of science course in Mechatronics Engineering. One of my core modules is Electrical Components. I'm stuck in understanding one of the key parts in this module. I've been asked to derive the Tangential and Normal forces of the rotor shown below. I've...
  43. S

    Where to Buy 24VDC Electric Motor up to 500 kg Load, 180 RPM, 1000Nm Torque

    Anyone know where will i be able to get a 24VDC Electric Motor [with or with gear reduction] that can take up to a maximum of 500 kg load at a maximum of 180 rpm at a maximum torque of 1000Nm? Appreciate that someone can help. Thank you.
  44. Runei

    Electric motor on the wheels of an RC-car

    Hello Im doing a physics project and I am trying to come up with an idea for calculating the torque done by an electric motor on the wheels of an RC-car, and the resulting acceleration of the car. We have modified the car with some stronger batteries, and now we are in a dilemma. Each...
  45. A

    A battery drives an electric motor which raises a 20 kg mass at a steady speed.

    1. A battery drives an electric motor which raises a 20 kg mass at a steady speed of 3m/s vertically upwards. If 90% of the electrical energy supplied is converted to mechanical energy and the current flowing is 5 A, find the emf of the battery. 2. W=QV p=mv P=IV K.E=.5mv^2 3...
  46. H

    Finding a Custom Sprocket for an Electric Motor Bike

    I have an electric motor that I want to use with a bike chain and not the small chain that is already on it. Using cad and getting a custom sprocket made might be the way to go, but finding a site that sells them would be more than likely be cheaper. I found that it is called a dual-d boreand is...
  47. J

    Optimizing Electric Motor Core Materials for High Frequency Performance

    Hello Everyone, I'm interested in designing my own custom electric motor for some experiments and I am trying to do some research on some of the various laminated steel materials available. I have a decent working knowledge of general magnetic material properties, saturation characteristics...
  48. C

    Electric motor used as Generator?

    theoretically I believe this is possible: basically I am trying to decide if I could use an electric motor as a generator to charge a battery source, and when needed use it as a motor as well. I think the only issue is the rpm's which it is operating at, to get the most...
  49. S

    High voltage electric field does not stop electric motor

    I have made an attempt at understanding electric field and the effect they have on electrons by making the following test (see attached picture). What I did was take a 12 volt battery and connect a fan of a psu with it so the fan starts to turn by the flow of electricity, of course. I then...
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