Forum Discussion
jharrell
Feb 13, 2019Explorer
pnichols wrote:
Hmmm ... they do say it's designed to "operate" at 1200-1500 engine RPM ... maybe that's to insure proper control of frequency (i.e. to keep frequency "around" 60 Hz in that RPM band).
But they do say it will not be damaged at up to 10K RPM spin speed. This is a bit misleading in that customers could possibly infer that the frequency of 60 Hz was somehow kept constant regardless of spin speed up to 10K RPM.
Note at the bottom of the page that they sell an optional solid state voltage regulator to insure constant voltage level regardless of spin speed.
All of the above begs a question: What good does it do to have constant voltage level at any spin speed but at the same time having frequency (Hz) not maintained regardless of spin speed?
I guess that's the solid engineering that Honda uses in their inverter generators to insure constant voltage and frequency at all engine speeds - with only the amount of available current being affected by engine RPM?
Their manual can be found here:https://www.fabcopower.com/manuals/Power%20Mite%20Manual.pdf
This is what they say:
If you have a specific use for 60 cycle frequency, the shaft of
the AC generator must turn at 3600 RPM, at this speed the
AC generator will produce exactly 60 cycles.
Note: The engine speed would be approximately 1200 to 1600 rpm to
obtain 60 cycles at full load. If the engine is equipped with a tachometer it would not give a true indication of the AC generators output frequency because of different pulley sizes. The shaft speed of the PowerMite™ must be turning at exactly 3600 rpm. The speed can be measured by using a stroboscopic thahometer or by plugging an AC frequency meter into the power outlet.
And
If the Power-Mite® is running over l0,000 rpm will it damage
hand tools or lights?
ANS: No, tools and lights are AC/DC and they run more efficient at
higher cycles up to 75 HZ.The Power Mite can withstand
intermittent speeds up to 10,000 RPM with out damage, if
properly installed.
Not sure how 60Hz at 3600 means 75 at 10,000 but still don't want 75 Hz either.
Inverter generators like the Honda are very different, going from 3 phase AC rectified to DC then inverted back to AC at the exact frequency needed so they are RPM independent. My Onan 4000 just has an RPM governor and tries to stay at 3600 rpm but it not perfect goes from 58 to 63Hz depending on load.
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