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30 kw Northern lights

Discussion in 'Generators' started by Bucci, Aug 1, 2021.

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  1. Bucci, Aug 1, 2021
    #1
    Bucci

    Bucci New Member

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    I have a 30 kw NL with 10,000 hrs. It’s been a great genset. The other day I noticed it was showing 114 volts with a 80 amp draw. If I reduce the draw to 40 amps I get 120 volts. Any idea what’s going on. Thanks. Fred
  2. Capt Ralph, Aug 1, 2021
    #2
    Capt Ralph

    Capt Ralph Senior Member

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    It's tired.
  3. Capt J, Aug 1, 2021
    #3
    Capt J

    Capt J Senior Member

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    Tired and can't keep rpm's up with a higher load.
  4. Pascal, Aug 1, 2021
    #4
    Pascal

    Pascal Senior Member

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    Could be tired but first how many hours on primary and secondary?

    6 volts drop is not much. How is the frequency holding up under load ?
  5. Capt J, Aug 1, 2021
    #5
    Capt J

    Capt J Senior Member

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    I had a generator like that and a tune up helped it quite a bit.......adjusted valves, rebuilt injectors etc. etc.
  6. DOCKMASTER, Aug 1, 2021
    #6
    DOCKMASTER

    DOCKMASTER Senior Member

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    Could also be a governor issue where it’s not applying enough engine power under heavy load?
  7. Bucci, Aug 1, 2021
    #7
    Bucci

    Bucci New Member

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    10,000 original hours. The injectors and fuel system where done this spring. Valve clearance etc all done. The mechanic says it’s running very strong. No smoke on start up etc. I will check the line frequency tomorrow under that load.
  8. Danvilletim, Aug 2, 2021
    #8
    Danvilletim

    Danvilletim Senior Member

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    Freq for that genset should be set to 62.5 w no load.
  9. Pascal, Aug 2, 2021
    #9
    Pascal

    Pascal Senior Member

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    Usually freq is the first thing impacted by engine issues as rpm directly controls freq. whereas voltage is controlled by the regulator

    whenever I ve had voltage issues, the voltage regulator was the culprit
    d_meister likes this.
  10. Bucci, Aug 3, 2021
    #10
    Bucci

    Bucci New Member

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    Completing the circle. The following
    0 load 120/121 volts feq 62.9
    40 amps 120/119 volts feq 61.9
    63 amps 120/117 volts. Feq 61.9
    100 amps. 122/ 115 volts. Feq 61.3
    What do you think. Thanks Fred
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  11. Capt Ralph, Aug 3, 2021
    #11
    Capt Ralph

    Capt Ralph Senior Member

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    Lil different than your first post numbers.
    Looks damm good. What was your problem again?
    Last edited: Aug 3, 2021
  12. Bucci, Aug 3, 2021
    #12
    Bucci

    Bucci New Member

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    I was concerned about the drop in voltage on L2 at 100 amp load. This is a 30 kw gents.
  13. Capt Ralph, Aug 3, 2021
    #13
    Capt Ralph

    Capt Ralph Senior Member

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    If you were to take an O scope to the leads, your 121 Vac would look pretty noisy and your volt meter is picking up on the peaks of this noise.
    A better true RMS digital volt meter may show you a better read out but that is not really necessary either.
    Under a load, This noise cleans up a little and your volt meter reads a cleaner signal.

    Your loosing 1.5 Htz, 45 RPM total trial. I feel that is pretty good.

    You may try another AVR to clean up the exciter to output wave, but I don't think you will gain anything.
    Last edited: Aug 3, 2021
  14. Capt Ralph, Aug 3, 2021
    #14
    Capt Ralph

    Capt Ralph Senior Member

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    May-be,, May-be a little un-balanced Volt wise.
    Without an amp meter per leg, won't know if it's really un-balanced on current draw.

    Without an O scope, don't know if the wave form is cleaning up or if it is over burdened.
    I do not think AVRs regulate the top & bottom differently.

    I note the other leg Vac went up. This may be a symptom of un-balanced loading also.

    So, the big questions?
    What prompted you to start looking at the gen-set? A problem?
    Are you just checking up on the gen-set?
    Or really looking for a problem?
    Last edited: Aug 3, 2021
  15. Capt Ralph, Aug 3, 2021
    #15
    Capt Ralph

    Capt Ralph Senior Member

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    If it's a 30, then large boat?
    Then large boat, a second gen-set?
  16. Pascal, Aug 3, 2021
    #16
    Pascal

    Pascal Senior Member

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    It ain’t broken. Don’t try to fix it :)

    These numbers look pretty good to me. If anything I d low RPM to get freq down 1 Hz but probably not even worth messing with it
  17. Capt Ralph, Aug 3, 2021
    #17
    Capt Ralph

    Capt Ralph Senior Member

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    Older ACv powered clocks run by the 60htz freq.
    Newer clocks do not.
    Other than this lil issue, I would not mess with the gen-set to set Htz.
    Maybe trace your loads to ensure the set is balanced. Ammeter on each leg may help.

    Still have those questions in post #14.
  18. Bucci, Aug 4, 2021
    #18
    Bucci

    Bucci New Member

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    I run Two gensets on my boat. The starboard one same hours has consistent voltage on loads up to 100 amps. The port one I notice the other day had the voltage drop. If we have heavy loads I will run both trying to keep them loaded up. We have At Sea converters to balance the loads. I wasn’t looking for a problem it was just some thing I noticed. These gensets are in an 85 ft Pacific mariner by Westport. They have been rock solid. When I saw the voltage drop I was wondering if some issue was coming down the line.
  19. Capt J, Aug 4, 2021
    #19
    Capt J

    Capt J Senior Member

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    Could be the fuel filters are getting a little dirty. Your boat is designed to run off of one generator 99% of the time. The generators are better off with a heavier load on one generator than 2 with a half load.
  20. DOCKMASTER, Aug 4, 2021
    #20
    DOCKMASTER

    DOCKMASTER Senior Member

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    Do you get similar readings on the other gen if you are only running one at a time? You have two gens, why not perform a side by side test? This will help you narrow down if you have a gen issue or something external to the gen. To me this looks like a load balance issue. As you get to heavier loads the regulator is trying to compensate but you have way more load on L2 than L1 and that’s why your voltage on L1 is actually going up.
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