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Generator harmonics question(s)

Started by Unknown November 26, 2017
    Years ago I adjusted a neighbor's generator so that it put out 60
cycles at 120 volts. I used a TEK 465B 'scope to look at the
frequency. I saw the major 60 cycle waveform and then a lot of smaller
waveforms at higher frequencies. I was told that these harmonics were
typical of small generators. 
   Today I am replacing the voltage regulator on a small generator and
adjusting the governor. I expect I will see the same thing as with my
neighbor's generator.
   Looking inside the generator all I see is rotating coils inside a
stationary coil. The rotating coils are energized with DC from the
voltage regulator.
   Looking at old power plant pictures and video it looks as if those
giant generators were built the same way. And many of them are still
in use today.
   But I know that the  sine wave from the wall has been very good for
almost since, if not since, the first generator installation at
Niagara Falls.
   So how do they get the good clean AC from these big generators? Or
maybe it's not so clean and is instead filtered. If so how is this
done? And can I do this myself without too much effort? Is the effort
even worth it?
   Until the voltage regulator failed on my generator it ran my stuff
at home just fine. The fridge, freezer, lights, phone and router. I
didn't try any computers. So maybe I don't need to even consider
filtering the generator output.
   But I do see a lot of generators that advertise "pure sine wave
output" from an inverter that is part of the generator electronics. So
maybe a pure sine wave is important for some electric or electronic
stuff. Clocks for example.
   Anyway, thanks for reading. And for any answers too.
Cheers,
Eric
On Sun, 26 Nov 2017 11:18:08 -0800, etpm@whidbey.com wrote:

> Years ago I adjusted a neighbor's generator so that it put out 60 >cycles at 120 volts. I used a TEK 465B 'scope to look at the >frequency. I saw the major 60 cycle waveform and then a lot of smaller >waveforms at higher frequencies. I was told that these harmonics were >typical of small generators. > Today I am replacing the voltage regulator on a small generator and >adjusting the governor. I expect I will see the same thing as with my >neighbor's generator. > Looking inside the generator all I see is rotating coils inside a >stationary coil. The rotating coils are energized with DC from the >voltage regulator. > Looking at old power plant pictures and video it looks as if those >giant generators were built the same way. And many of them are still >in use today. > But I know that the sine wave from the wall has been very good for >almost since, if not since, the first generator installation at >Niagara Falls. > So how do they get the good clean AC from these big generators? Or >maybe it's not so clean and is instead filtered. If so how is this >done? And can I do this myself without too much effort? Is the effort >even worth it? > Until the voltage regulator failed on my generator it ran my stuff >at home just fine. The fridge, freezer, lights, phone and router. I >didn't try any computers. So maybe I don't need to even consider >filtering the generator output. > But I do see a lot of generators that advertise "pure sine wave >output" from an inverter that is part of the generator electronics. So >maybe a pure sine wave is important for some electric or electronic >stuff. Clocks for example. > Anyway, thanks for reading. And for any answers too. >Cheers, >Eric
No "inverter" can beat the sine-wave quality of a good M-G (motor-generator) set. ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | STV, Queen Creek, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | It's what you learn, after you know it all, that counts.
In article <dp3m1dln0mil8o747s4k82la0uc2vu81hv@4ax.com>, 
etpm@whidbey.com says...
> > Years ago I adjusted a neighbor's generator so that it put out 60 > cycles at 120 volts. I used a TEK 465B 'scope to look at the > frequency. I saw the major 60 cycle waveform and then a lot of smaller > waveforms at higher frequencies. I was told that these harmonics were > typical of small generators. > Today I am replacing the voltage regulator on a small generator and > adjusting the governor. I expect I will see the same thing as with my > neighbor's generator. > Looking inside the generator all I see is rotating coils inside a > stationary coil. The rotating coils are energized with DC from the > voltage regulator. > Looking at old power plant pictures and video it looks as if those > giant generators were built the same way. And many of them are still > in use today. > But I know that the sine wave from the wall has been very good for > almost since, if not since, the first generator installation at > Niagara Falls. > So how do they get the good clean AC from these big generators? Or > maybe it's not so clean and is instead filtered. If so how is this > done? And can I do this myself without too much effort? Is the effort > even worth it? > Until the voltage regulator failed on my generator it ran my stuff > at home just fine. The fridge, freezer, lights, phone and router. I > didn't try any computers. So maybe I don't need to even consider > filtering the generator output. > But I do see a lot of generators that advertise "pure sine wave > output" from an inverter that is part of the generator electronics. So > maybe a pure sine wave is important for some electric or electronic > stuff. Clocks for example. > Anyway, thanks for reading. And for any answers too. > Cheers, > Eric
For the power line there is enough load to smooth out many things. The 'pure' sine wave is mostly just advertising hype. Just about all the modern electronics use switching power supplies and unless the incomming waveform is really bad it will have almost no effect. While I did not play with it too much, I have one of the Harbor Freight $ 90 generators. The voltage regulation on it is not all that great, but an old computer and monitor I hooked to it for a test worked fine. I bought it mainly to power a drill in an out building and an electric pole chain saw. As many of the clocks depend on the AC power being exectally 60 Hz it is doubtful they will keep very accurate time on any home generator. The power grid will slightly speed up and slow down the frequency, so that over a long period of time (say a month) the time will even out.
On 11/26/2017 3:06 PM, Ralph Mowery wrote:
> In article <dp3m1dln0mil8o747s4k82la0uc2vu81hv@4ax.com>, > etpm@whidbey.com says... >> >> Years ago I adjusted a neighbor's generator so that it put out 60 >> cycles at 120 volts. I used a TEK 465B 'scope to look at the >> frequency. I saw the major 60 cycle waveform and then a lot of smaller >> waveforms at higher frequencies. I was told that these harmonics were >> typical of small generators. >> Today I am replacing the voltage regulator on a small generator and >> adjusting the governor. I expect I will see the same thing as with my >> neighbor's generator. >> Looking inside the generator all I see is rotating coils inside a >> stationary coil. The rotating coils are energized with DC from the >> voltage regulator. >> Looking at old power plant pictures and video it looks as if those >> giant generators were built the same way. And many of them are still >> in use today. >> But I know that the sine wave from the wall has been very good for >> almost since, if not since, the first generator installation at >> Niagara Falls. >> So how do they get the good clean AC from these big generators? Or >> maybe it's not so clean and is instead filtered. If so how is this >> done? And can I do this myself without too much effort? Is the effort >> even worth it? >> Until the voltage regulator failed on my generator it ran my stuff >> at home just fine. The fridge, freezer, lights, phone and router. I >> didn't try any computers. So maybe I don't need to even consider >> filtering the generator output. >> But I do see a lot of generators that advertise "pure sine wave >> output" from an inverter that is part of the generator electronics. So >> maybe a pure sine wave is important for some electric or electronic >> stuff. Clocks for example. >> Anyway, thanks for reading. And for any answers too. >> Cheers, >> Eric >
> > As many of the clocks depend on the AC power being exectally 60 Hz it is > doubtful they will keep very accurate time on any home generator. The > power grid will slightly speed up and slow down the frequency, so that > over a long period of time (say a month) the time will even out. >
I have 60 Hz. batteries in my wall clock.