3 Phase Brushed Generator AVR Problem

Discussion in 'The Projects Forum' started by dimuthudw, Aug 16, 2014.

  1. dimuthudw

    Thread Starter New Member

    Aug 16, 2014
    7
    0
    Hello,
    I have a very old 35kVA generator, but unfortunately its AVR was broken. So I purchased a brushed AVR (model number: STL-F-1) online. The supplier sent me the wiring diagram also, which I have attache here, but when I connected it like that the generator still did not produce any output.
    Basically I measure the DC voltage that went to the exciter but it was zero. Tried changing the "volt" and "stab" resistors but still nothing happened. I contacted the seller and he says the circuit diagram he has provided is correct and it should work. Is there something I'm doing wrong here or am I missing something. Any help on this would be greatly appreciated.

    Thank you
     
    • avr.jpg
      avr.jpg
      File size:
      441.5 KB
      Views:
      101
  2. shteii01

    AAC Fanatic!

    Feb 19, 2010
    3,393
    497
    You say you bought STL-F-1.

    Diagram says STL-F-2

    Looks like they sent you wrong diagram.
     
  3. dimuthudw

    Thread Starter New Member

    Aug 16, 2014
    7
    0
    Yes I noticed that also, STL-F-1 is the 15A model while the STL-F-2 is the 25A version.
    When I inquired about the circuit the supplier said both will have the same diagram.
     
  4. inwo

    Well-Known Member

    Nov 7, 2013
    2,433
    315
    The top part of the diagram is not clear.

    I don't see any input power to regulator.:confused:

    You must have power to excite field.

    Depending on design, field may need to be "flashed" if generator has been idle a long time.
     
  5. dimuthudw

    Thread Starter New Member

    Aug 16, 2014
    7
    0
    The top part is only the field. The AVR is suppose to control the voltage supply to that (exciter), but I don't understand how that is achieved with this wiring diagram. This is why I'm asking for help :(
     
  6. inwo

    Well-Known Member

    Nov 7, 2013
    2,433
    315
    What I mean is. If there is no external power supplied. Excitation of the field relies on power output of the generator.

    And as power output relies on the field being excited, if there is no PM or residual magnetism, then the field must be excited to get the process going.

    A safe way is to disconnect the field wires and connect to a dc power source for a split second.

    On portable generators with no regulators, I backfeed ac line voltage into the output thru a 60 watt lamp. Then I don't have to open it up.

    In your case, I'd try flashing the disconnected field with a battery.
     
  7. dimuthudw

    Thread Starter New Member

    Aug 16, 2014
    7
    0
    When my first AVR went out of commission I did connect an external DC power supply to the exciter and the generator did produce an output. I do understand what you are saying, but still I have serious doubts that the supply to the exciter can be controlled by such circuit arrangement. Nevertheless I will give a try to your method and see how it goes.

    Thanks a lot for the suggestions.
     
  8. dimuthudw

    Thread Starter New Member

    Aug 16, 2014
    7
    0
    When flashed it did produce an output, but I was not able to control the output with the AVR "volts" resistor. The exciter voltage was a constant and did not vary. :(
     
    Last edited: Aug 16, 2014
  9. debe

    Well-Known Member

    Sep 21, 2010
    947
    184
    This is more like how a generator AVR would be connected. Most ive worked on have a separate winding to generate a DC voltage for the Field. And the U & V are the voltage sense part of the circuit. The other circuit doesn't make sense to me??
     
  10. dimuthudw

    Thread Starter New Member

    Aug 16, 2014
    7
    0
    Thanks a lot for the help debe, your circuit also make sense to me. But the problem is, in my AVR there is only F1, F2 and the sensing input U and V , there is no connetion ports to "volts" and "stab".

    The actual image of the AVR I have attached.

    [​IMG]
    [​IMG]
     
  11. debe

    Well-Known Member

    Sep 21, 2010
    947
    184
    Thanks for the pict of the reg, I notice it has a large SCR or Triac in it. Its more likely to be wired up as in this circuit.
     
    Last edited: Aug 17, 2014
  12. debe

    Well-Known Member

    Sep 21, 2010
    947
    184
    Last picture didn't load properly.
     
  13. dimuthudw

    Thread Starter New Member

    Aug 16, 2014
    7
    0
    Thanks again debe, but still there was no change. The exciter voltage could not be adjusted. I'm beginning to feel that may be this AVR is busted :(
     
Loading...