Talk:Electric generator

hola cami y andre jajajaja

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Unit of generator?

I think that unit of generator should be in KW not in KVA, b/c when we write KVA then, it gives an idea of having power factor and in generator there is not any concept of power factor. Plz clear it.

202.125.143.68 21:25, 23 October 2006 (UTC)

Not so, in practice electrical engineers are as interested in the kVA or MVA rating as the kW or MW rating. Power factor is very important in specifying a generator, expecially where a low power factor is required due to transmission system reasons, for example - each per-cent rated power factor below 1.0 adds between 1.5 and 2% to the cost of a large hydro generator, for example. --Wtshymanski 22:04, 23 October 2006 (UTC)

sir, thanx for clearing confusion, but still i think that generator converts mechanical energy into electrical energy, so why should there be any concept of power factor in it, that (p.f)involves in transmission and u know p.f is there, when more than 1km tr/line r there, again u need transformer for that trn. that p.f is not involve there in generator.

Mithoo 20:59, 1 November 2006 (UTC)

plz send me an answer of above question.

so the question still not clear

KW is the amount of work being done, typically used for the driving side (motor, turbine etc.) of the generator, and the output end of the generator is rated in Volt Amps (VA). VA is a calculation, taking the Voltage and Current ratings of the ourput end. Both are used interchangeably though.

The Power Factor is only relavent in Alternating Current (AC) generators. Direct Current (DC) generators do not have a Power Factor. If there is not a page dedicated to the Power Factor, there should be one. It is a very interesting subject.Nly8nchz 03:47, 31 July 2007 (UTC)

Maximum power

Hello, I am looking to make a generator as part of a school project. I want to test to find its electrical power output. I know that for a battery, its power output is greatest when the load resistance is equal to its internal resistance. Does this also apply to a generator? If so, how might I find the internal resistance of my generator?

Perhaps the answers to these questions could be put into the article, as I think they would be interesting and useful.

Yes, this applies to generators just like batteries. The internal resistance is essentially the resistance of the windings, slip rings/brushes, wiring etc. You can measure it with an ohm meter, but depending on the type of generator (AC vs. DC), you might be better off measuring the voltage drop under load. When the voltage drops to half of the open circuit voltage, the load resistance is equal to the internal resistance. A toy motor will work as a generator, but the internal resistance is not small, though. Madhu 19:17, 2 September 2005 (UTC)

Can someone provide some proof that batteries or generators have the greatest power output when the load is at the same resistance as the internal resistance? I do not believe this is correct. The output should be the greatest at the lowest load resistance. This will pull the most current out of the source.Nly8nchz 03:58, 31 July 2007 (UTC)

The maximum power theorem can be applied to generators, but they are not usually designed to run at maximum power output. With a matched load, the transfer efficiency is only 50%, which means that half the power is wasted inside the generator. For a laboratory demonstration this might not be important, but it would be disastrous in a power station. --Heron 16:46, 3 September 2005 (UTC)

Can you provide some links where we can read about this? From my experience operating motors and generators, I have never seen 50% efficiency out of a generator. From turbine driven electrical generators, the power output is very close to Volts*Amps*Power Factor. If you have a load that has an extremely low Power Factor (AC Generators), then you can get have a lot of power lost, but that is very inefficient. If you have a generator, you would theoretically have it set up to provide power at whichever power factor that your loads are going to be. Typically, the windings will be set up in either Wye or Delta, depending if you are going to be supplying capacitive (computers, televisions, etc.) or inductive (typically motors, lights, etc.).Nly8nchz 03:58, 31 July 2007 (UTC)

Co-generation possibility? Since the generator will make "waste heat" inside a generator, is this heat ever recovered and utilized so as to drive any sort of turbine and thereby turn another generator? If the answer is "yes," then can this fact be applied in this or any other Wiki articles on electricity generation? Joel Russ 05:47, 19 January 2007 (UTC)

(In the regime in which they're usually run,) Generators are pretty efficient. As a result, I don't think the exhaust stream from a generator is very hot and it would be hard to utilize that heat in any kind of classical co-generation scheme. Perhaps the heat could be used to pre-heat air going into the boiler furnaces, but the generators in big power stations tend to be inconveniently located for that purpose.

Typically, steam driven generators have a very low temperature exhaust, compared to the inlet temperatures. Efficiency is greatest when you take the most energy out of the steam, which means the cooler the outlet, the more efficient the turbine is.Nly8nchz 03:58, 31 July 2007 (UTC)

User:MKR 12:04, 19 January 2007 (UTC)

Generators are very efficient (>95%) at converting mechanical to electrical energy, but the heat engines that drive them (turbines, etc.) are limited by the 2nd law of thermodynamics to about 46% efficiency. So more than half the energy in the fuel is released (by the steam plant, not the generator) as waste heat. Cogeneration as you mentioned above, use this waste heat. In many European towns the houses are heated by waste heat from power plants. --Chetvorno^TALK 03:44, 14 July 2008 (UTC)

Motors & generators

The link to commutator on this page points to the wrong entry. Maybe we need to add a second meaning to this entry to describe a commutator as a system of brushes and a collector to alternate the direction of current to/from the coils in an armature of an electric motor or electrical generator.

Describe various modern types of dynamos, three phase dynamos for mains power distribution and simple AC and DC dynamos for use in vehicles.

Also mention that a dynamo is constructed very similarly to an electric motor and most types of dynamos can be used as motors and vice versa, at least in theory.

saigon_from_europe:

I would rather say: "all common types of generators could be used as motors, and vice versa."

I think it would be more accurate to say that generators and motors are theoretically interchangeable, but that practical machines are nearly always used only in one mode or the other. Many small motors such as used in household appliances are not going to generate significant electric power no matter how fast you spin them. --Wtshymanski 23:15, 26 Jan 2005 (UTC)

In direct-drive, diesel-electric submarines, the electric motors are used as generators and used to charge the batteries when driven by the diesels on the surface or when snorting. 82.111.65.142 15:21, 4 May 2005 (UTC)

The motor-generator sets on the submarines have the ability to change the resistance of both ends of the generator, which is how you can make either end the motor/generator.Nly8nchz 04:05, 31 July 2007 (UTC)

This is mentioned in the submarine article and is characteristic of hybrid automobiles. I've also seen it in locomotive cranes, where the generator used to run the propulsion motor and magnet is also used to start the engine. So the roles of a rotating machine can be interchangeable, but it's not always the case. For instance, if I take the shaded-pole ac motor of a record player and spin it, I'm not going to get any meaningful amount of power out of the winding. --Wtshymanski 15:46, 4 May 2005 (UTC)

I worked at a combined cycle power plant where we had a combustion turbine driven generator that was baseloaded at about 160 MWs. During startup of a combustion turbine you have to get the thing spinning pretty fast before you ignite. They actually started up by motorizing the generator - they have a "Load Commutated Inverter" which acted as a variable frequency drive, energizing the generator stator coils in concert with the regular excitation system energizing the rotor coils. It was a pretty neat trick and something I never expected to see in such a big machine.

I'am really sorry for replying so late. You are right, most of machines are used only in one mode. In practice 99.9% of all electric power in the world is made by dinamos, and 99% of power used by motors is used by squirell cage motors. But your point about household appliances is not the best one. Small machines are often inefficient, hence low output in generator mode. On the other hand, your point proves that some electic machines are more suitable to be motors (or generators) than others. In your hair drier, for instance, you have so-caller collector motor; it is DC serial motor run on AC current. Rotating such motor will produce DC current (not AC), and even that only if rotated below critical speed (defined by motor parameters). I think that we musr reorganize this article just in order to avoid this kind of problems. Generally speaking, from theory's point of view, our article here is a complete mess; see my post below on this talk page, you'll see what is the usual division of elelctrical machines. We should cover all of them and then explain why they are or why they are not used as generators. Saigon from europe 23:25, 7 August 2005 (UTC)

The 99.9% figure that you state is not correct. The squirrel cage (Induction) motors are A/C only. There are many DC motors around as well. I will not argue that most of the A/C motors are Induction (Squirrel Cage), as they are really efficient at the correct slip speed.Nly8nchz 04:05, 31 July 2007 (UTC)

Picture needed

This is terrible. Instead of all that equivalent circuit stuff that's only understandable by electrical engineers, how about that nice simple picture of a wire moving through a magnetic field that we've all seen in every other elementary description of a generator? My tools and skills aren't quite up for this...--Wtshymanski 16:45, 22 Apr 2005 (UTC)

For the moment, you could steal the three diagramatic pictures over at Electric motor and simply give them new captions. But I agree that the classical "single turn coil rotating in a magnetic field" picture would be more helpful.

Atlant 18:16, 22 Apr 2005 (UTC)

The pictures for "motor" are beautiful, but I don't have the software to edit them - so I can't change the polarity marks. I'll check with the creator of these images to see if he/she can do a quick revision. --Wtshymanski 01:01, 23 Apr 2005 (UTC)

What about some reorganization?

Although I am an electical engineer, I am not familiar enough with English terms to be the one who will organize a new system. Still, I think we are not systematic enough. What I want to say - during my studies, our clasification basically went this way (have in mind that terms are probably incorrect in English, this is how we call them in Serbian, which is probably based on German names): all electric machines are divided to two groups - AC and DC machines. AC machines could be synchronous and non-synchronous (i.e. induction motors). At the same time, they could be one-phase or three-phase. We should then pay attention to turbogenerators and hydrogenerators (both are 3-phase AC synchronous, but they differ drastically in construction), as most widely used systems. DC machines could be serial, parallel and independent (regarding how they produce the field). We should then explain why and where what types are used, and with what limitations. I believe that we should exactly follow the pattern in the [Electric_motor] article. Saigon from europe 21:48, 2 Jun 2005 (UTC)

Your taxonomy and your English are both fine; this matches pretty closely any textbook on the topic.

Atlant 22:25, 2 Jun 2005 (UTC)

Two views?

Do we really need to views of this portable gererator?. Surely one picture is quite adequate.--Light current 16:21, 9 September 2005 (UTC)

I agree, I am deleting one. Rex the first 23:35, 9 March 2006 (UTC)

Terminology

Wouldn't it be better to use the term engine-generator set or some such term to identify the pictured portable generators, and those described in the Small to medium generators and Large generators sections? Perhaps the small to medium and large generator sections should be combined under the heading Engine-generator sets. A Power station generator section could be used to describe hydro-electric and steam turbine generators. C J Cowie 18:06, 21 October 2005 (UTC)

It probably would, but since most would assume, without ever considering it much, that a generator 1. runs on gas and 2. makes electricity. Not considering that many other devices and sources of energy can generate electricity. Your suggested section reorganization sounds good, and let's go with engine-generator. Not sure what set means, is it a set of devices Engine and generator I usuaily only hear that word when abbreviating generator to genset, anyway... --D0li0 05:58, 23 October 2005 (UTC)

Patents

The list of patents should go - even if you look at them, you won't learn much useful in understanding electric generators. --Wtshymanski 17:55, 27 October 2005 (UTC)

Someone went to some effort to compile the list and it may be historically interesting, but it doesn't add to this article. Would it make sense to move the relavent entries to the Edison and Tesla articles? --C J Cowie 19:39, 27 October 2005 (UTC)

Synchronous/asynchronous generators

Should something be added about synchronous/asynchronous generators? I'm working on something else right now, so here's some sources if anyone wants to take a crack at it: Windpower.org, Dromey Design. -- Kjkolb 05:57, 19 December 2005 (UTC)

There should be a section for all types of A/C and D/C motors and generators. Someone has to take the time to do it.

Schematics

Maybe some basic conceptual schematics for the basic types of generators should be present (like the Faraday generator or the Dynamo). It would greatly increase the information the article gives with very little extra work —The preceding unsigned comment was added by 82.76.30.78 (talk • contribs) .

I was just thinking the same thing. I plan on adding a basic schematic for a generator with brushless excitation, seeing as that's the type I'm most familiar with. -W0lfie 17:17, 27 February 2006 (UTC)

Gyro-Gen?

A recent editor added text about the Gyro-Gen, a way of using wave power to drive a generator. While this is valuable text, I don't think it belongs in this article because it's really discussion about an interesting prime mover of the generator rather than anything about electrical generators themselves.

Your thoughts?

Atlant 13:32, 23 June 2006 (UTC)

Agree. I removed it yesterday. The same text is in Wave power anyway, so I didn't destroy any information. --Heron 17:33, 25 June 2006 (UTC)

Low efficiency??

In the section on low power generators, there's a sentence that reads:

Nevertheless, the maximum efficiency is only around 60% for the best generators - 40% is more typical - due to the use of permanent magnets.

Can you supply any verification for this? In A/C generators, the efficiency usually follows power factor. Most generator designs are set up pretty well. From my experience, 60% efficiency is not common. Depending upon the power factor (A/C), you will typically see 70-90% efficiency. From looking at the meters that were on the motor generators, we were seeing way better than 40-60% efficiency. You can calculate efficiency by looking at the power needed to drive the generator, and then looking at the voltage and current being supplied to the loads. Has anyone else here operated motors & generators. I would like to see what others have to say.Nly8nchz 04:12, 31 July 2007 (UTC)

Where do these numbers come from? I don't see why permanent magnents necessarily contribute to low efficiency. If power is lost, where does it go? I can believe that poor mechanical coupling with the bike results in power loss, but that's not the fault of the magnets or the generator proper. Madhu 03:37, 26 October 2006 (UTC)

The info is wrong. Low efficiency is due to small size, the bigger you go the more efficient the generator. Permanent magnet generators are more efficent rather than less, electromagnet takes power which reduces efficiency. However electomagnet field is easy to vary which makes voltage regulation easy over range of loads.

This is wrong as well. Size does not necessarily mean more efficient. Larger generators typically create more heat, that is just wasted energy. You can get more efficiency by adding windings, upping the control field (current) or spinning the generator faster.Nly8nchz 04:12, 31 July 2007 (UTC)

electrical generator question

Electrostatic generators are used for hi scientific experiments requiring high voltages. Because of the difficulty of insulating machines producing very high voltages, electrostatic generators are made only with low power ratings and are never used for generation of commercially-significant quantities of electric power. Before the connection between magnetism and electricity was discovered, generators used electrostatic principles. The Wimshurst machine used electrostatic induction or "influence". Some electrostatic machines (such as the more modern Van de Graaff generator) uses either of two mechanisms:

Charge transferred from a high-voltage electrode Charge created by the triboelectric effect using the separation of two insulators (the belt leaving the lower pulley)

i don't understand "Electrostatic generators are used for hi scientific experiments requiring high voltages." what is "hi?" Poiuyt580 20:51, 29 March

I would think that these electrostatic generators put out a very high voltage, but the current output levels are very low. That might be why the power rating is so low.Nly8nchz 04:16, 31 July 2007 (UTC)

Tidal generators

can someone please explain to me " How does a generator work ? " also help me out on "Tidal generators" Please also tell me the advantages and disadvantages of wind and tidal generators.

The tidal generators use the rising and falling of the tide to move an arm in and out of a generator, thus inducing a voltage, and allowing current to flow. I am not sure which is the armature and which is the stator, but it would be nice for someone to elaborate.Nly8nchz 04:16, 31 July 2007 (UTC)

Dynamo should become its own article

I am on the verge of taking over the dynamo page which is currently just a redirect to here. Another editor does not like the expanded discussion I put on the disambiguation page about the ambiguous meaning of dynamos in the early days of electrical experimentation, so I guess it really belongs as a separate article.

A dynamo is many things, and a generator is just one aspect of its meaning, so it's not really appropriate being integrated into just this article. They say be bold so here goes..

DMahalko (talk) 01:17, 11 January 2008 (UTC)

Lots of new image content ... article probably will now need splitting

Expired US Copyright!

I've been wanting to spend a weekend adding volumes of technical imagry to Wikipedia from this nine volume 1917 Hawkins Electrical Guide. And so I'm currently in the process of massively expanding this article with new technical and educational diagrams and information.

Alas this article will be very image top-heavy now, and will probably need splitting to keep the download speeds managable for people on dialup.

DMahalko (talk) 22:33, 12 January 2008 (UTC)

Please don't shoot me, but I've added 14 technical illustrations and about 9 kilobytes of text to this article in the last 24 hrs. Yawn, time for bed. Maybe I'll add some more in the morning, to further bloat this already bursting article. :-)

Since I eventually expect to be adding hundreds of images from these books, I'm setting up a sort of scrapbook/shrine to these public domain books here:

DMahalko/1917_Hawkins_Electrical_Guide

DMahalko (talk) 12:07, 13 January 2008 (UTC)

Images that help explain the content of hte article are fine, but I don't think we need too many steps in the development of the obsolete Gramme ring. Perhaps all those illustrations are better separated into a Gramme article. Wikipedia is not a textbook on generator design and an overview of why the Gramme ring isn't used is all that is necessary here. Similarly, detailed development of multipolar fields is perhaps more than this article needs. --Wtshymanski (talk) 15:31, 13 January 2008 (UTC)

From reading through the wikipedia help pages, there is a mention that as articles grow, splitting and subpages are a natural part of the expansion of the encyclopedic content. There is room in the wikispace for a detailed field coil article, a detailed Gramme Ring article, a detailed theory of commutation article, etc.

The difficulty with this subject matter is that the information is applicable across so many different devices. Virtually everything about generator design also applies to motor design, and to rotary converter design. I am trying to figure out how to best split this into subsections which would allow for generalized cross-referencing from any of those other articles. I don't claim to be an engineering professor, so knowing how to smartly split off subsections for better comprehension by the reader is the challenge. DMahalko (talk) 16:24, 13 January 2008 (UTC)

I've now taken a deep breath and moved the entire section on dynamos off to the new Dynamo article I created, leaving behind a short summary but with a really cool high-current dynamo image explaining why nobody uses DC generators for much of anything anymore -- the commutators of high-power dynamos are very complicated and need lots of care and maintenance. Modern AC alternators for power generation are almost maintenance-free in comparison.

Click on that high-current dynamo illustration and take a look at the full-resolution version. I scanned it at 600 dpi, and with the quality of that image you can see every screw, every thread.. even the wood grain of the underlying support frame. I love these old Audel's books.

I may not touch this again until next weekend, but the field coil design and the excitation sections will probably become separate articles as well, since they are also common across other rotating magnetic machinery. DMahalko (talk) 08:41, 14 January 2008 (UTC)

Wrong Picture

"Side view of a large Perkins diesel generator" is actually a steam locomotive, Union Pacific #4004 to be exact. —Preceding unsigned comment added by 75.81.99.177 (talk) 03:57, 22 January 2008 (UTC)

Why no mention of generators driven by steam turbines?

A major part of the electricity generated worldwide is done by using steam turbine drivers ... yet steam turbine drivers are not discussed in this article. The article discusses piston drivers and gas turbine drivers ... but not steam turbine drivers. Why? - mbeychok (talk) 06:29, 6 July 2008 (UTC)

Advise on creating electricity

I would like some help on the following:

I make use of a ventelation fan with the following specifications: Two fans driven by two 300kw motors moving aproximitly 140 cubic meters of air. Any suggestions on making use of this to create electricity for other use.

Appreciate any help regards Riaan —Preceding unsigned comment added by 196.38.64.208 (talk) 18:48, 25 July 2008 (UTC)

The sun is not a source of mechanical energy.

At the begining of the article it states . . .

The source of mechanical energy may be a reciprocating or turbine steam engine, water falling through a turbine or waterwheel, an internal combustion engine, a wind turbine, a hand crank, the sun or solar energy, compressed air or any other source of mechanical energy.

The sun or solar energy is not a source of mechanical energy, radiant energy yes but not mechanical.

Must be written by the same idiot who thinks that the sense of time is an other physical sense such as "Taste" or "Hearing".

But that might be just my opinion. GeeOh (talk) 02:49, 18 February 2009 (UTC)

Whoa. Steady on there. Remember, we're all bozos on this bus and the fellow who's been teaching the subject to PhDs for 30 years is an exact peer in authority with the 13-year old who watched a special on cable TV last month. Do not taunt happy fun editor. Why not just clip out the offending text - WP:BOLD and all that. --Wtshymanski (talk) 15:27, 18 February 2009 (UTC)

"When you put on the nose, it grows."

Yes, I understand, and all that . . . "or I shall taunt you a second time"

If I cut out the offending words someone will come back and re-insertt them. I have seen it over and over again. This is a problem with some "loaded" articles.

I wonder if some one would start a "Wikipedisms" article? GeeOh (talk) 08:47, 23 February 2009 (UTC)

The revised wording seems to have stuck for five whole days now. More than one editor has mused about the problems of our editorial model, for example see things like WP:WRONG. --Wtshymanski (talk) 16:47, 23 February 2009 (UTC)