Odd thing with generator...

zorbazorba Senior MemberPosts: 19,607 Senior Member
I'm still messing around with this 700/900 watt HF generator. Plugged an electric heater into it - that has a wattage control dial. Set it to its lowest setting, indicated as 500 watts. Whether or not that's real, who knows? Ran with it like that for a couple of minutes, with an indicated output voltage of 117. Suddenly, the engine note changed briefly (like it would at a load change). I don't know if this heater (it has electronics in it) went off line at this time or not - more missing data. In any event, the engine went back to its normal speed judged by my calibrated audible tachometer (ear). However, it was putting out an indicated 65 volts. Removed the heater - no change. Plugged in a 100 watt light bulb - very dim. So I believe the 65 volt reading. Unplugged the light bulb, and watched the voltage slowly rise back up to about 122 - normal for no-load, plugged in 200 watts of incandescent load, still running at 122-ish volts.

What in tarnation caused its output to sag in this manner? I'd expect it to either trip its breaker or at least sound overloaded if the heater was lying and pulling too much power. It sounds to me like the field coil excitation suddenly dropped off, and took a bit to rebuild its magnetic field - but if that's indeed the case, why?
-Zorba, "The Veiled Male"

"If you get it and didn't work for it, someone else worked for it and didn't get it..."

Replies

  • BigDanSBigDanS Senior Member Posts: 6,803 Senior Member
    The heater likely has a thermostat and has a resistant coil. When heating element draws lot of juice, and when not, much less, hence the generator on and off.

    D
    "A patriot is mocked, scorned and hated; yet when his cause succeeds, all men will join him, for then it costs nothing to be a patriot." Mark Twain
    Alcohol, Tobacco, Firearms and Explosives.... now who's bringing the hot wings? :jester:
  • Farm Boy DeuceFarm Boy Deuce Senior Member Posts: 6,083 Senior Member
    I had something similar happen to a slightly larger generator a couple weeks ago.

    This generator is a 250KW 480V 3phase. It was running 19 10hp fans and a 25 (I think) kva 240/120 transformer. It ran everything fed by the transformer except three vacuum motor fans. When those fans tried to come the battery backups would beep.
    I am afraid we forget sometime that the basic and simple things brings us the most pleasure.
    Dad 5-31-13
  • zorbazorba Senior Member Posts: 19,607 Senior Member
    BigDanS wrote: »
    The heater likely has a thermostat and has a resistant coil. When heating element draws lot of juice, and when not, much less, hence the generator on and off.

    D

    Normal no-load output for this genny is 123-125 volts. The voltage should have gone up when/if the thermostat stopped calling - NOT down!
    -Zorba, "The Veiled Male"

    "If you get it and didn't work for it, someone else worked for it and didn't get it..."
  • joeg52joeg52 Member Posts: 73 Member
    cpj wrote: »

    As to what's wrong......it has a 25 hour lifespan....not needed to break in for 25 hours...

    +1, hf just doesn't last.
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