What is Alternator: Definition and 132 Discussions

An alternator is an electrical generator that converts mechanical energy to electrical energy in the form of alternating current. For reasons of cost and simplicity, most alternators use a rotating magnetic field with a stationary armature. Occasionally, a linear alternator or a rotating armature with a stationary magnetic field is used. In principle, any AC electrical generator can be called an alternator, but usually the term refers to small rotating machines driven by automotive and other internal combustion engines.
An alternator that uses a permanent magnet for its magnetic field is called a magneto. Alternators in power stations driven by steam turbines are called turbo-alternators. Large 50 or 60 Hz three-phase alternators in power plants generate most of the world's electric power, which is distributed by electric power grids.

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  1. S

    Why Does My Battery Keep Running Down in a Closed Loop Charging System?

    Hi i embarked on a project to design a battery charging system using an alternator, an electric motor and a battery all connected in a closed loop. The battery powers the electric motor and in turn the electric motor powers the alternator and finally the alternator charges the battery. My...
  2. S

    Alternator on a long transmission line

    Could it be dangerous to connect an alternator to a long transmission line,if the line has high capacitance?if dangerous then why? please explain...
  3. A

    Maximizing Alternator Output Voltage for Long Cable Runs

    Hi All, I am new to this forum and would appreciate some help from you experts! I am trying to turn a turbine (@40RPM) using an alternator via a gearbox. I have a 12v/110A alternator which i am running at 1120RPM (On its lower limits) and a 25A constant load. The voltage at this speed is...
  4. K

    Limiting alternator output with resistors in parallel

    Hello, this is my first post here! I am building a bicycle-driven generator using an alternator and battery (12v) pulled from a dead car. I can easily spin it up to the point where the alternator self energizes and produces output, but on a dead or low battery, the load on the alternator is so...
  5. R

    Does alternator work as dynamometer?

    does alternator work as dynamometer?? i'm doing small engine test rig to analyze it performance characteristic. then,i connect the pulley to alternator.thing that i need to considered is power that can produced from alternator must be larger that small engine.from engine specification, it can...
  6. E

    Force necessary to spin an alternator at the rated RPM?

    Can anyone tell me how to determine the force necessary to spin an alternator at the rated RPM?
  7. D

    Alternator which is light in weight

    friends... one urgent help .. i need an alternator which is light in weight and the shaft should be easy to rotate because we have a small impulse turbine as power source ... when i enquired a shop out here .. he is asking me some specs... like 12v * 25 amp or 200 *1.5amps .. the speed...
  8. R

    Alternator Rewinding: Length & Gauge for 240V/20A & 15V/90A

    Hi, I am looking at rewinding an alternator and have a few questions. I believe that the length of the wire determines the max volts and the gauge determines the max amps. Is there a formula or some test I can do to determine the length and gauge I need the wire to be. I have two...
  9. N

    Advice on regulating a 6V motorcycle alternator.

    I hope it is acceptable to ask for advice here. I am based in the UK and currently restoring a British 1964 Velocette LE motorcycle. It is fitted with electrical components made by the, now defunct, Miller Company (also British). The vehicle has a 6V 3 coil alternator with permanent magnets...
  10. E

    Dynamo, Generator, Alternator?

    Hey, bit of an odd projection question here, Im working on generating a current(enough to power a few leds) in a juggling club. I was originally thinking of a "shake" generator like this <a href="http://www.sciencebuddies.org/science-fair-projects/project_ideas/Elec_p020.shtml" >This</a> With...
  11. R

    Alternator Q: DC Output of 84V & 300A?

    Hi, I have a rather weird question to ask. I'm in need of an alternator that will give me a DC output of around 84v (maybe more) and 300 amps (more or less). To my knowledge, no such alternator exists. Not even a $3000 alternator will do it (and I'm not willing to pay that much anyway). So...
  12. M

    What is the maximum output of a vehicle alternator and how can it be calculated?

    Hello everyone, I have a question that I have been unable to find an answer to. I am interested in salvaging a vehicle alternator in an attempt to create a homemade generator. I understand that household electronics' needs are measured in watts, but I can't seem to figure out how to calculate...
  13. R

    Benefits of induction coil over an alternator?

    I'm just wondering about what benefits there are to building / using an induction coil as opposed to other devices to create devices for spark gap experiments. I am referring to the induction coils with a primary winding and secondary windings with enormous numbers of turns - similar to...
  14. e2m2a

    Efficiency of linear alternator

    Interesed in practical maximum efficiency of linear alternators. Suppose an object with a permanent magnetic attached moves along a linear track with a constant velocity, such that its kinetic energy is 1 joule. The object "collides" with a linear alternator or generator, such that the magnet...
  15. B

    Can a 12V DC Motor Efficiently Power a 120 Amps Alternator at 2100 RPM?

    Is it possible/meaningful to use a 12V DC motor to run a 120 amps. Alternator at 2100 rpm ? If yes, what kind of DC Motor should be used (RPM/Watts/HorsePower)
  16. M

    Measure current from an alternator

    Hi, I have few alternators(one is 3phase), and I want to test the current generated for each alternator at a same rpm. however, what is the proper way of doing this? what is the connection should be? is there a need to convert them to DC, and charge to the battery while testing? or any other...
  17. M

    Alternator for Low Wind Speed Wind Turbine.

    Hi I've a wind turbine which have to run under a very low wind speed, from 2-3m/s. Currently, I'm using Envirotek V20, the result is around 1.5V-2.5V, and current is 0.3mA or nearly zero. My aim is to achieve 50W. Any suggestion for the alternator which I should use? p/s: without...
  18. Q

    Design & Build Instructions for a Turbine & 3 Phase Alternator

    3 phase alternator. any good links to*** is what I meant in the title
  19. Q

    What would be the size of an alternator roughly

    What would be the size of an alternator roughly... that outputs 10megawatts? 3 phase.
  20. hxtasy

    Switching off alternator during hard acceleration

    Some time ago I was wondering about disconnecting my alternator from my race car just during a quarter-mile drag run. The lesser friction on the motor's drive belt system would be ideal. Then I realized that spinning the alternator itself is not that much of a problem, it spins pretty freely...
  21. A

    Turbo Alternator: How Can It Increase Vehicle Efficiency?

    Im a mech engineering student and I am very interested in alternate fuels, and better mpg. So I was thinking and did some research on the topic I am posting about and found very little so I am looking to experienced moders for some input. what if you were to hook up a turbocharger so that the...
  22. A

    Engineering Alternator Problems (3 phase and single phase AC Motor)

    Homework Statement 1. A 4MVA, 13.3kV, 60Hz, 3 phase, delta-connected alternator has an effective resistance of 5.2 ohm/phase and a combined armature reactance of 54 ohm/phase. Determine the full-load generated voltage per phase, a. At unity pf, b. at 0.8 pf lagging, and at 0.866 leading pf...
  23. D

    Can a Car Alternator be Submerged in Oil for Underwater Power Generation?

    Hi I need to build a 12V alternator inside a pressure casing that will be driven by a propellor. This will be mounted on the rear on an oceanographic sensor platform that will be towed behind a ship on a long cable with the ship's forward motion providing the spinning of the prop, for the...
  24. A

    Input/Output voltage relationship for alternator

    Hello again, I'm here with a request for some advice. Hopefully I won't need as much this time as it's something I'm a bit more clued up on :rolleyes: I'm trying to work out what output voltage will occur on the stator coils of my alternator in relation to the excitation voltage in the...
  25. K

    Comparing Star vs Delta Connection Alternators

    Hi:rolleyes: , I want to know something about Alternator. first what is the different between Star Connection Alternator and Delta Connection Alternator, and why if we want to find the Line Voltage from Star we use this formula Line Voltage = 1.73 * phase Voltage, exactly why 1.73, where did...
  26. K

    Which is better for creating DC power, a Generator or an Alternator?

    Hi:smile: , How are you? I am a again. I've question about what is diffenent between Ganerator D.C and Alternator. I know the Alternater always give us A.C but we use rectifier when we want to D.C, but what is the better Generator D.C (it is one Machine) Alternator, when we want to D.C...
  27. M

    Can a Car Run Solely on a Battery and Alternator?

    Could you run a car with just a battery and an alternator by having the alternator recharge the battery by using the motion of the wheels and other parts? ~Kitty
  28. S

    Difference between Generator and Alternator

    Hi guys, As per topic, what actually differentiates a generator and alternator?
  29. T

    Car Alternator Output: Voltage Decrease in Heavy Loads

    Hi. I have what seems like an easy question, but I'm having trouble answering it myself. As say a standard 3-phase car alternator has a heavy load placed on it, the voltage regulator would increase the current into the windings creating a greater magnetic field and thus increasing...
  30. R

    Building a Battery Charger with Car Alternator

    hi i wish to build a battery charger using a 3/4hp240voltac motor driving a 55amp car alternator will this work has anyone done this before and will my caravan batteries be oka i have a gen set to drive the electric motor all these questions i hope to be reveled rolly
  31. M

    Finding Turbine Angular Velocity given Net Head, GPM, and power from Alternator.

    An alternator attached to a water turbine generates 35 Watts given 50 feet of head and 10 gallons per minute. Assuming that the efficiency of the alternator is 50%, is it possible for me to find the angular velocity from this information? If so, how would I do it?
  32. Tyger

    The self-exiting alternator, a tale of invention.

    I knew that if you drove a three phase induction motor attached to the line at above line frequency it would change from a motor to a generator. So one day it popped into my mind that if you put capacitors across the terminals of a three phase motor and drove it above the L-C resonant frequency...
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