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Running generator below its capacity

  1. Apr 30, 2010 #1
    Dear all,

    I have no science back ground , I have purchased a 30KVA gas generator, for my farm house, I would like to know if I run it well below its capacity will it be harm full for the generator or it will get hot. It’s a American generator with cooling tower design, which I have converted to radiator for cooling purpose.

    Please guide. Thanks AcidBurn_Dubai
  2. jcsd
  3. Apr 30, 2010 #2


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    Staff: Mentor

    No harm will come to it: it is designed to run at a variety of loads.
  4. May 2, 2010 #3


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    Gold Member

    You will likely see high oil consumption, bore glazing and possibly high combustion blowby with continued use at low loads. Performance won't be an issue.
  5. May 2, 2010 #4


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    The generator should never be fully loaded. Adding more load on the generator applies more counter-torque to the engine, so running the generator at its rated kVA is similar to running your car at maximum torque.

    Keeping the generator below 80% of its rating is good.
  6. May 3, 2010 #5


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    Shawn, I disagree.

    Generator engines are developed for continuous operation at high loads, where a car engine isn't. While some components will wear more quickly at the rated power, there's nothing wrong with running a genset at its rated power for sustained periods (especially if that's a prime or continuous rating). Standby ratings normally have restricted running hours to prevent any engine damage, if this is the case the documentation will advise accordingly. Otherwise load away!
  7. May 4, 2010 #6
    If it uses lubricating oil, consider synthetic for less friction/heat. Make sure there's nothing nearby blocking air/heat flow. Lower output means lower efficiency but less heat. To monitor, remote thermometers are ~$20 in home/garden stores. You'll want to check the temp of the round case of the electric generator, not the fueled engine.

    If it's going to fail from too much heat, it will happen some hot summer when you've been running it at full load for quite a while. Check often, remove dust clogging air channels. General quality overall may suggest how much abuse it will stand.
  8. May 4, 2010 #7
    Are you comparing an old vehicle engine, powering a heavy load at slow RPM? In that case, insufficient air is drawn through the radiator as the engine is worked hard; a belt-driven fan blade is too slow.

    Your new generator is designed to work fine as long as you don't overload it and ambient air isn't too hot. You can always add heat sinks/fins/grease to any part that overheats (in Dubai?). If this is a critical application, add another gen and run both at half load, switch to single gen/critical circuits if one gen fails.
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