Generator Help

Discussion in 'General Electronics Chat' started by rizwanahmed, Sep 6, 2010.

  1. rizwanahmed

    Thread Starter New Member

    Sep 2, 2010
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    I have 2.5 kva 50 hertz natural gas generator . Can i run this generator on low rpm does it any harmfull to alternator (maximum speed is 3600RPM) some one told me that the slow RPM could overheatup the alternator motor.
    Another question is that how to adjust rpm; through governer or through idle speed screw.


    Thanks

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    Last edited by a moderator: Sep 7, 2010
  2. Jaguarjoe

    Active Member

    Apr 7, 2010
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    The output capacity and frequency of the alternator changes with speed. You should be OK running at a lower speed keeping in mind its capacity and frequency will be lower.
    To change the speed of the engine, you will need to talk to the generator manufacturer, the engine manufacturer, or some mechanic knowledgable in this kind of thing.
     
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  3. marshallf3

    Well-Known Member

    Jul 26, 2010
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    Double post, he's asked this same question again only 21 minutes later and I responded to that one.

    You chance not only burning up the generator but also anything that it's powering.

    What do I care? It's not my money and/or equipment I'll stand to lose.
     
    rizwanahmed likes this.
  4. rizwanahmed

    Thread Starter New Member

    Sep 2, 2010
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    sorry for your disturbance
    really sorry
     
  5. retched

    AAC Fanatic!

    Dec 5, 2009
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    If you are trying to save fuel by running the generator slower, while getting the same amount of power, you will not.

    It would be nice if you could run the generator at 10 RPM and still get full output.

    If you figure out how to do that, your gonna be a rich man. (or woman) ;)
     
  6. rizwanahmed

    Thread Starter New Member

    Sep 2, 2010
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    You are giving a suggestion of to much lower rpm. It is better that i can move rotter through by myself with 50 rpm
    Happy now
     
  7. SgtWookie

    Expert

    Jul 17, 2007
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    It's really pretty difficult to give a good answer without knowing your generator/alternator's manufacturer and model number.

    Many have their output frequency fixed to the rotational speed of the generator itself. Some modern generators synthesize the output, and so can maintain a precise frequency output independent of the rotational speed.

    If you are powering purely resistive loads, like incandescent lamps, resistive heaters like a hot plate, or a universal motor (that has brushes, like an electric drill) then the frequency is not important.

    However, correct frequency is very important to many types of motors, and older fixed-frequency transformer power supplies. If you try to operate those types of loads at lower frequencies, they will use a great deal more power than they do at the correct frequency.

    A couple more items are the cooling of the generator, and field current. The slower the generator is turning, the more field current is required to produce the same power output. More current = more heat. If the cooling fan is directly coupled to the generator's shaft, then it will be less efficient at lower speeds, reducing the amount of cooling supplied to the generator. The increased heat and current could be damaging - but that also depends upon the environment you are operating it in.

    The hotter your environment, the more cooling air you will need to remove a given amount of heat.

    Your best bet would be to contact the manufacturer of your genset, supplying your model number, your load and type of load(s), and your operating environment.
     
    Last edited: Sep 7, 2010
  8. rizwanahmed

    Thread Starter New Member

    Sep 2, 2010
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    sir your comment are very helpfull for me specially about the overheatup thoughts,
    my machine is giving to much temperature at low rpm so as your advice the rpm should be at least doubled.

    Thanks
     
  9. Dyslexicbloke

    Active Member

    Sep 4, 2010
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    Whatever you do with the RPM, personally I wouldnt recomend anything other than what is recomended, do it with the governer.

    Any other aproach will muck up your carburation and damage your engine.
    Not electronics I know but its important none the less

    Al
     
  10. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    Most small engines such as Briggs&Straton and Tecumseh etc, are made to run at 3600RPM. That is the usual governed/regulated speed setting. That should give the best fuel usage and cooling of the engine.

    As a general rule a carbureted engine uses more fuel at idle/low speed than at the governed speed.
     
  11. rizwanahmed

    Thread Starter New Member

    Sep 2, 2010
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    Yes you probably right but the problem is that some time consumption of power is high and some time is low depend on several reasons but geneartor is producing same amount of energy which might be as waste during low consumption of power usage.
     
  12. rizwanahmed

    Thread Starter New Member

    Sep 2, 2010
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    For the purpose of cooling can we use some external fan or table fan to bring cool air to generator is that method can increase the service life of generator do u all agree upon that?
    I personally using this technique for cooling which is good and also i feel that the temperature was in under control during extreme load.
     
  13. marshallf3

    Well-Known Member

    Jul 26, 2010
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    Guess I should be grateful that we've got a relatively stable power grid all across this country.
     
  14. rizwanahmed

    Thread Starter New Member

    Sep 2, 2010
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    Some parts are still out of power or power outages.
     
  15. SgtWookie

    Expert

    Jul 17, 2007
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    It will not be as reliable as the built-in fan that is physically mounted to the shaft of the generator. When the fan eventually stops working (which WILL happen sooner or later) you risk burning up the generator.

    How well does the table fan cool the generator when it's blades are not turning?

    Do you realize that if the output load is light, that the engine will not burn as much fuel as when there is a comparatively heavy load, as it was made at the factory?

    Perhaps what you should do is to shop for a newer generator that synthesizes it's output waveform rather than having to operate at a fixed speed. They DO make such generators now. That way you can sell your existing generator while it is still working. If you keep experimenting with it, I am afraid that you will wind up having to buy a new generator in the dark, while your old generator is picked up by the junk man.
     
  16. marshallf3

    Well-Known Member

    Jul 26, 2010
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    You in the U.S.A. ?

    I live in Oklahoma so we've got advantages and disadvantages. Due to the number of severe storms and tornados we receive they built our power grid to be pretty strong and keep improving on it as they can. Unfortunately some of these storms can be so strong that they'll knock out about anything.
     
  17. marshallf3

    Well-Known Member

    Jul 26, 2010
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    It's going to take power to run an extra fan, probably more than the original shaft mounted one already uses. Then there's the matter of aerodynamics ....

    If they had a way to improve on the design they probably would have already done so and just charged more for it in the beginning.
     
  18. rizwanahmed

    Thread Starter New Member

    Sep 2, 2010
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    We talk about aerodynamics we talk about fan every thing we got but some one say that you burn the genset through fan some one say this is good keep it up.

    I think some areas are in US they got moisture across whole 12 month season this problem is the cause of many other problems.

    I mean that machinery are going to wear rapidly specially in texas.
     
  19. rizwanahmed

    Thread Starter New Member

    Sep 2, 2010
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    I live in texas

    Power is a major critical factor in some part of the state.

    Severals of thunderstorm and dust storm.
     
  20. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    Generators that produce AC at 60 Hz often have gasoline engines that run at 3600 rpm, but 50 Hz generators often run at 3000 rpm. (50 Hz = 50 cycles per second = 3000 cycles per minute, thus 1 engine rpm equals 1 cycle) However, alternators (genheads) can be designed to run at almost any speed desired. For example, many diesel engine powered generators run at 1800 rpm to produce 60 Hz power and 1500 rpm to produce 50 Hz power.

    Some generators have a feature called "idle control," which slow the generator down to idle speed when no load is attached. Then, when there is a demand for electricity, the idle control circuitry detects the demand and increases the engine rpm back to standard speed. As someone else said, the answer to your question depends upon the exact design of your generator.
     
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