Question on power factor and harmonic distortion

Thread Starter


Joined Dec 12, 2012
Some friends of mine are moving into an apartment building that contains its own hydroelectric generators, and supplies all of its own power. The website claims they generate 6 Million KWH annually, of which they consume 4m kwh and sell 2m kwh to the utility. The math works out to a generating capability of almost 700 kw. US based, so 120v 60hz.

My question is: Since this building is a somewhat closed electrical system and lacks the "inertia" of a larger electrical grid, is it more susceptible to distortion of the waveform, surges, and under-voltage? Will someone turning on a dryer affect the entire building?

I ask because if the smaller electrical system is more susceptible to harmonics and surges, investing in a UPS with line conditioning for sensitive electronics may be well worth the cost.


Joined Mar 14, 2008
Offhand I would think the source impedance of such a large generator would be pretty low and the fluctuations in your building due to large appliances turning on won't be any worse than that of a comparable building powered from the grid. But that's just my guess. ;)


Joined Feb 12, 2009
I think harmonics and surges are slightly more likely but modern electronics should be able to cope.

If they sell power to the utility then they will be "grid tied" so the frequency will be synchronised to the grid.