What is Dc generator: Definition and 46 Discussions

In electricity generation, a generator is a device that converts motive power (mechanical energy) into electrical power for use in an external circuit. Sources of mechanical energy include steam turbines, gas turbines, water turbines, internal combustion engines, wind turbines and even hand cranks. The first electromagnetic generator, the Faraday disk, was invented in 1831 by British scientist Michael Faraday. Generators provide nearly all of the power for electric power grids.
The reverse conversion of electrical energy into mechanical energy is done by an electric motor, and motors and generators have many similarities. Many motors can be mechanically driven to generate electricity; frequently they make acceptable manual generators.

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  1. P

    Is a Larger DC Motor Needed for Low Wind Speed Power Generation?

    Hello, I am not sure if this is the correct forum. I was torn between Electrical Engineering and Mechanical Engineering and I thought I would start here. I have been kicking around an idea for a DIY project and realizing I don't know enough about DC motors to find the parts I need. In this use...
  2. M

    Engineering DC Generator calibration plot

    Summary:: Hello Got the following plot (please see below), and am trying to figure out the phenomena behind it (plot behaviour) What do you guys think? It's a DC Generator to be calibrated. On the x axis: the ratio between the power of the generator / nominal power of the generator, while on...
  3. K

    Why is S=2*pi*r*l in the equation for induced voltage of a DC motor?

    Induced voltage of DC motor isV=Blv where B= phi/S where S=2*pi*r*l and magnetic flux is phi=B*2*pi*r*l as shown in the picture. that leads to the equation V=PZ*phi*N/60amy question is, why do we set S=2*pi*r*l Shouldn't magnetic flux 0 because the magnetic flux of a closed surface is 0...
  4. A

    Engineering Speed of a DC generator is proportional to the generated voltage?

    I'm confused as I'm aware speed is directly proportional to the EMF, but is it proportional to the voltage as well? If the speed of a DC generator is halved and everything else is remaining constant the EMF will have so will the output voltage half
  5. K

    DC generator: Induced EMF of a single coil armature

    Hi. I am reading a textbook about simple DC generator. The situation is if we are rotating a single armature coil within a constant field B, the induced emf will be (if we are to only think about the magnitude), emf= B*l*W*omegaB = magnetic field l = length of the coil W = width of the coil...
  6. PainterGuy

    Some basic questions about a DC motor and a DC generator

    Hi, The picture below shows a DC generator. The magnetic field is uniform. As the coil rotates clockwise, the right side of coil is moving downward and the left side of coil moves upward. Using Fleming's right hand rule, one can deduce the direction of conventional current in both sides of...
  7. Quix270

    What would happen to a small DC generator if it is spun at higher rpm?

    What would happen to a dc small generator if it is moved at more rpm that is it designed to? Does it will produce more, less or the same? I have this question since I while. Thank you
  8. D

    DC generator question -- what is happening at no load?

    In the case of a d.c. generator, if V=E–IaRa when current flows through the armature, why does V = E at no load? Why does the resistance element become disregarded at no load? Is this because the resistance can't cause the voltage to drop at no load?
  9. K

    How to wind a DC generator coil?

    I want to make a dc generator and not sure my design will work. I will wind the coil on a donut shape disk and put 6 rectangular magnets on a disk rotor with North Pole face the coil. Please see attached pictures. Will this design works or have problems? Can I have one continuous coil or I...
  10. J

    How does does a DC generator work?

    The way I understand most generators that are used in plants is that they take the heat form combustion or fission and use It to create steam to run a turbine with magnets on it that create AC power over a coil. how could a dc generator work?
  11. J

    External characteristics of a DC generator are.... (multiple choice)

    Homework Statement Homework Equations The Attempt at a Solution I think External char = Magnaetic characteristics - Armature reaction drop - Ohmic drop since we're subtracting these values from voltage. But book answer is D. Magnetization char + armature reaction - Ohmic drop. Is book...
  12. A

    Position of brushes on the commutator in a DC generator

    i am having a hard time understanding why do we place the brushes on the Magnetic neutral axis, the textbook simply says, because this is where the current reversal takes place, is the point where emf from different meet is the same as the point of current reversal?
  13. D

    Which supercapacitor range is needed to run a 48V DC motor?

    I'm doing a project where I need to hand power for dc motor (12V or 24V) and charge a super capacitor, and then use it to drive another 48V dc motor. I want to know which Super capacitor will be suitable? Please give suggestions for Super capacitor specifications for both 12V and 24V that will...
  14. Narayanan KR

    A motor design to defy Lenz' law?

    1. The two rotors (purple, green) are electricaly isolated but mechanically fit to rotate along same axis 2. The motor action on the left side rotor will move the armature set, this will produce currents in right side rotor that will pass via a variable load. 3. do you see the magnetic fields...
  15. ranju

    Does opposing cross flux with interpoles aid in commutation in a dc generator?

    Homework Statement See , in the methods of improving the commtuation , one of the method is using interpoles now what I think that interpoles aids commutation by nullifying the reactance voltage in the conductors. Though this point is mentioned with the working but it is also mentioned that...
  16. B

    AC Power vs. Field Current of a DC Generator: Explained

    I am trying to understand this curve; it is AC Power vs. Field Current of a DC Generator. I am not sure what its significance is? What it's telling me? Can someone please explain it to me? See attached image. BTW... Pac = AC Power If = field current Poc = open circuit...
  17. L

    Why are DC generator loops wired in a non-traditional manner?

    Given a simple DC generator with a single loop in the presence of a magnetic field such as the one below, typically, the analysis involves how each rectangular loop's terminal ends up on opposite sides of an armature housing each of the coils. The analysis is fairly straightforward to then...
  18. D

    Predicting DC generator response

    I am creating a scale model wind turbine using a DC motor as a generator and would like to predict the motor response analytically. Generally speaking, the flow will spin the rotor (as in the turbine's), which will spin the motor, and then there will be what I'm calling the motor response, and...
  19. smruti

    DC Generator Converted to Alternator

    can a dc generator be converted into an alternator?
  20. M

    What Should You Know About Using DC Motors in Wind Energy Projects?

    Hi, I'm doing research for my science project. I chose Wind energy and I need to learn a few things about DC Motors, Who is a good manufacturer for 6-9V .5 amps DC motor/generators? What happens if the generator goes over the recommended RPMs? How do you keep the RPMs between the minimum...
  21. H

    Homemade diesel-electric platform truck

    Hi, this is my diesel-electric conversion for what was a battery only powered platform truck. Its got a 30hp diesel engine, a 6 Kw DC generator, and another 6 Kw AC generator. One thing to point out is that I'm running it only with the generators, no batteries. Here's some pics of it: Diesel...
  22. G

    Current measurement of a PM DC generator

    Hi, I'm trying to use a small PM DC motor as a generator to convert mechanical energy to electrical energy. I couple that small generator to another DC motor with spur gears and I measure the current of that small generator while it is driven by the DC motor at fixed speed. The circuit of...
  23. H

    How Many Poles Does a 1200 kW DC Generator Have?

    1. Find the number of poles for a 1200 kW separately excited generator, if the average voltage between commutator segments is 15 V and the armature ampere-turns per pole on full load is 10000. The generator has single turn coil and is lap connected. Ignore all losses. Homework Equations...
  24. H

    DC Generator Reference Books for Aeronautical Engineering Students

    I have completed a DC generator chapter from my course book. Below mentioned questions have been asked in previous examinations, but my course book doesn't help in solving these. Please help me with the reference books which will be helpful in solving these type of questions. I am pursuing...
  25. Q

    DC Generator Output: Vmax, Poles, Ripples, EMF

    1) My understanding is that the output of a DC generator has the form Vmax*|sin(2πft)| for 2 poles. Having more poles makes the output smoother but it would still have ripples. Is this correct? 2) In many places, I have seen the EMF of a DC generator written as: \phi * (NZ/60) * (P/A). What...
  26. S

    Can You Make Your Own DC Generator for Your College Project?

    hello, I need a dc generator which would generate 19v and 1.5A current(roughly i want it to generate 30watts of power) at 1000rpm. I require it for a college project. the size of the generator should be small so that i can handle it easily.
  27. P

    Computer brush fan as dc generator

    Computer brush fan as dc generator Sir, I am using renewable soℝurces like wind for my project.. I need to supply 1.5 to 2 v dc to my amplifier circuit and then to load... I am using computer brush fan as source ...it just gave output upto 2.5v in ideal state when i connected to multimeter...
  28. L

    DC Generator: Equations & Graphs

    Hello everyone, I found on this website http://spiff.rit.edu/classes/phys213/lectures/lenz/lenz_long.html a very good explanation for AC generators. Particularly I am considering these two images: And I found those equations and graphs are quite interesting and wish to make a...
  29. M

    Calculating DC Generator Output via Input

    My dad is an electrical engineer, I am not. I am just a dumb race car driver. That said, I want to not ask him too much about all this stuff since I want to not look like a complete idiot. I feel that some of this stuff should be somewhat common knowledge, but alas, I am drawing a blank. I...
  30. B

    How to select the DC generator?

    Hello, I have designed a water turbine which weighs about 5.3 Kgs and it rotates at about 150 rpm from a head of 3 mtrs. The water is guided by a single 25.4 mm dia pvc pipe. I can achieve better rpm upto 200 rpm by increasing the flow. My plan is to generate steady 12 Volts DC for rural...
  31. H

    How Do DC Generators and Motors Work?

    I am studying Electrical machine course on my engineering semester. Can you you people provide me links for animation pics or video for working of dc generator and dc motors? Thanks for your help.
  32. S

    Is there an Optimal RPM for a DC generator?

    Is there an Optimal RPM for a DC generator?? I would like to ask if there is an optimal rpm for a DC generators? Or the faster it rotates, the more power it generates? The specification of the motor is as follow: http://www.mitsumi.co.jp/latest/Catalog/pdf/motorav_m25e_11.pdf
  33. T

    Calculating power of a permanent magnet DC generator

    Hello, I'm building a DC generator for fun (of the cardboard and lego variety). It is based on this model: How would you calculate the power output from that, assuming we know the strength of the magnets and the frequency of rotation? Are there any easy ways to increase...
  34. P

    DC Generator: Can AC Devices Function With DC Power?

    I have created blueprint for a DC generator.THEORITICALLY it is 100% power efficient,it involves no AC in PRODUCTION,i need to know whether AC devices we work daily cope up with dc power or not?
  35. X

    Calculating No-Load Voltage for DC Generator

    Homework Statement The ratings of a dc generator are given (16 kW, 250 V, and 64 A) when it rotates at 1000 rpm. Then the question asks to find the no-load voltage at 1000 rpm when there isn't a circuit hooked up to the generator. Homework Equations P = IV V = IR Kirchhoff's circuit...
  36. S

    Problem in deciding dc generator conecting to an inverter

    Hi, Its great to see a forum like this thanks for your efforts and thinking that PF can help me a lot. I Am ANANTH pursuing 3-2 B.TECH under J.N.T.U.H i am working on a project of wind energy to electrical energy. but the problem is what type of dc generator(rating) should i use? first I've...
  37. K

    What is the Full-Load Voltage of a DC Generator at 800 rpm?

    Homework Statement A dc generator is rated at 10 kW, 208 V, and 50 A when it rotates at 1000 rpm. The resistance of the armature windings is 0.56 . Assume that the magnitude of the magnetic field remains constant. (a) Calculate the "no-load" voltage at 1000 rpm (when there is no circuit...
  38. X

    Can a 2 HP DC motor drives a 5 kW DC Generator?

    Sorry for this noob idea but I'd like to know what happens if: A 2 HP DC electric motor is coupled to a 5kW DC Generator, will the 5kW DC Generator produce a 5kW output? What will happen to these two equipment. Thanks for the Reply!
  39. L

    Steam driven brushless DC generator - would this idea work?

    Hi fellow thinkers. I need constuctive criticism on the following:- Imagine a tube circling around into a closed loop - like a hoop. Inside the hoop is a ring of connected bar magnets all facing the same way. Pressurized steam is fed into the hoop - and exited in such a way as to spin the...
  40. X

    Steps for calculating dc generator output potential

    I need help understanding a few different items regarding electromechanics, and I'm not really sure where to start. Though the figures I have provided immediately seem impractical (coil melt down, coil explosion due to excessive rpm, inside dimensions exceeding their respective outside...
  41. Z

    Permanent magnet DC Generator questions

    Hello, I'm a mechanical engineering student currently working on a project which involves a compressed air motor and a Permanent magnet DC generator. I have this generator : http://www.windstreampower.com/443905_PMDCG.php Basically, we'll use the generator power output to determine the...
  42. U

    Why Does a DC Generator Crank Easily with No Load or Disconnected Wires?

    Hi, this question might seem really basic but I can't seem to wrap my head around it. For a DC generator (like the hand cranked ones used in science experiments) the generator gets harder to crank when connected to a resistor since it is harder to move the electrons through the wire/circuit. The...
  43. T

    DC Generator Question: How Can Loading Occur When Terminals are Open?

    I've had this question going in my mind for probably half a year, but I just have not had time to think about it too closely, so maybe someone with experience can help me. With a DC generator, it's torque is proportional to the current flowing through the input terminals. Basically the...
  44. C

    Calculating Power Delivery of a DC Generator with Varying Load and Speed

    DC generator question please help... Please could I get some help with the following question: An open circuit voltage of a d.c. generator driven at 1800rpm with rated field current is 85Volts. The resistance of the armature is 4.3 ohms. If a resistive load of 50 ohms is connected to the...
  45. D

    Help on DC TachoGenerator: Troubleshooting High/Low Voltage Issues

    Hi I need a help. I do have a DC TachoGenerator whereby i can measure the DC voltage if the shaft rotates. The problem is: When I rotate the shaft at CW, I got a fixed plus voltage.But when i rotate to CCW, the voltage is minus but slowly later it decrease to zero. (even the shaft still...
  46. M

    Permanent Magnet DC Generator

    If I have an internal resistance of the motor and the value of flux and the generator constant, can I simulate the system's performance by a circuit with two circuits in series, one being the internal resistance, and the other being the load, and the voltage source being the armature voltage?
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