AVR ???!!!!

Discussion in 'General Electronics Chat' started by banzai, Jun 7, 2014.

  1. banzai

    Thread Starter Member

    Jan 3, 2014
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    Hi guys

    Came across a diesel genny the other day, when i took a look inside the genset's panel i noticed that there where no AVR installed on it, just a three phase rectifier supplied from the alternator and the DC output goes straight to the brushes, what is going on here ?

    Its a 50 Hz 1500 RPM Diesel genny, three phase brush type alternator, with a line to neutral voltage of 230VAC, how is this achieved without an AVR ???



    This is some pics

    [​IMG]

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    I know i looks horrible :D
     
  2. Lestraveled

    Well-Known Member

    May 19, 2014
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    What does AVR stand for??
     
  3. banzai

    Thread Starter Member

    Jan 3, 2014
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    Automatic Voltage Regulator

    It takes care of the generator output voltage by controlling the excitation voltage
     
  4. Lestraveled

    Well-Known Member

    May 19, 2014
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    A friend of mind recently bought a surplus US military diesel generator. He refurbed it and called me several time for electrical advise. The subject was regulation and for parts for power factor correction. He never mentioned an AVS. He did have to rebuild the speed controller which was mechanical. He used it at a big event to supply power for 3 large RVs. I tried to call him but no answer.

    Mark
     
  5. banzai

    Thread Starter Member

    Jan 3, 2014
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    well i have done much work with generators but i haven't seen any thing like this, how is it possible to maintain a stable voltage without an AVR (Automatic Voltage Regulator) ?? this is weird :confused:
     
  6. alfacliff

    Well-Known Member

    Dec 13, 2013
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    with a mechanical governor, uses centrifugal force to control the throttle.
    very common on gas and diesel generator sets. holding rpm is more important, it sets the frequency of the output.
     
  7. banzai

    Thread Starter Member

    Jan 3, 2014
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    you are partially right, and that engine in the picture turning the alternator uses a mec governor, but that won't effect the voltage for that you will need some sort of a variable resistor or a AVR to control the current going to the armature.
     
  8. inwo

    Well-Known Member

    Nov 7, 2013
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    Could there be a resonating cap./winding?

    I don't know if the method is used or can be used on externally excited generators.

    It's common on small self excited gen sets.

    [​IMG]
     
  9. banzai

    Thread Starter Member

    Jan 3, 2014
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    Hmm... no i have looked multiple times and nothing inside the alternator except the armature,stator,commutator and brushes.

    Inwo could you explain how the cap excitation work haven't seen any thing like that before ?
     
  10. Lestraveled

    Well-Known Member

    May 19, 2014
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    I just got a call back from my friend that has the diesel mil spec generator. No AVR. No secondary winding/capacitor. It is a 5000 watt 208 three phase generator.

    Mark
     
  11. banzai

    Thread Starter Member

    Jan 3, 2014
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    Then i assume your friends generator has a brush type alternator with no automatic voltage correction, it has to be manually corrected/set trough a variable resistor that can be adjusted on the control panel.

    In my case i don't see any resistor of any kind ???
     
  12. Lestraveled

    Well-Known Member

    May 19, 2014
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    I did not ask directly about any voltage adjustments controls, but if there was one he would have mentioned it. I asked him about automatic voltage control. He said there was none.

    Mark
     
  13. banzai

    Thread Starter Member

    Jan 3, 2014
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    I don't know if i am missing something here, but how can you have a stable voltage without any some sort of control ???:confused:


    The cheapest alternators built like the Chinese ones has at least a variable resistor to control the voltage, i cant see how this works without any sort of control over the armature current
     
  14. Lestraveled

    Well-Known Member

    May 19, 2014
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    The following is my observation:
    I have a EU3000 (3000 watts). It weights 150 lb. My friends generator is rated at 5000 watts but requires four people to lift and move it. It is beast. They powered 3 big RVs for 3 days with it. Air conditioners on and off in Arizona. No issues.

    Mark
     
  15. banzai

    Thread Starter Member

    Jan 3, 2014
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    The EU3000 is what is called an inverter generator, it generates a DC voltage and supply's it to an inbuilt inverter that spits out a Pure Sine Wave voltage, they are cool though because they don't have to run at full speed all the time, the speed is adjusted automatically with the load. This thing got a complicated circuit inside of it that transform dc to ac and regulates the voltage, so yes it got an AVR inside of it. Do you have any model number of your friend's generator ?
     
    Last edited: Jun 8, 2014
  16. inwo

    Well-Known Member

    Nov 7, 2013
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    Any chance that's more than just a rectifier?
     
  17. banzai

    Thread Starter Member

    Jan 3, 2014
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    Well i thought about that, but unfortunately it only looks like a basic three phase rectifier :(
     
    Last edited: Jun 8, 2014
  18. Lestraveled

    Well-Known Member

    May 19, 2014
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    My friend had not responded with additional information. So based on what he has told me about his generator it appears to be a MEP-002A. If I am correct about this, it does have a voltage control module that controls excitation voltage. Sorry for any miss-information.
     
  19. inwo

    Well-Known Member

    Nov 7, 2013
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  20. Lestraveled

    Well-Known Member

    May 19, 2014
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    Yes, but I am only guessing.
     
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