Community Forums

Norm Mac · 01-02-2013, 04:31 PM

I undersand the value of a pure sine wave inverter for sensitive electronics, but doesn't the generator output modified sine wave?

Wouldn't this cause my sensitive electronics to run on MSW anytime the generator is running? And only run on PSW using shore power or battery power?

Isn't the inverter non-functioning when the generator or shore power is provided? During these times it becomes the converter for charging the batts.

BFlinn181 · 01-02-2013, 04:35 PM

A generator creates a pure sine wave since it creates AC by a rotating armature rather than an electronic circuit like an inverter that creates a modified sine wave.

Route 66 · 01-02-2013, 04:53 PM

If you have the Onan QD, they generate DC and have an internal inverter that is pure sine wave.

wa8yxm · 01-02-2013, 05:56 PM

There are, far as I know, 3 types of generators for this discussion......

Small "Contractor" jobs, portables usually in the less than 4,000 watt range (NOTE not firm on that) and with motors that run at 3600 RPM are "Mostly sine wave" but can produce a very dirty wave with some very nasty spikes... Alas, I can not link you to the article on thiese as it is a "Members only" area... (I happen to be a member, tough I tell folks that I do not plan on renewing.. You see. when the Life membership expires... So do I).

The next type is larger traditional generators, Generally 5,000 watts and up, Genrally these units have low speed motors 1800, 1200, less than 3,000 in any case.. These tend to produce fairly clean power. A good example of this type is the Onan Emerald I sit on from time to time.

I have never scoped it, mostly cause the scope I had was not really good enough for the job. but they are fairly clean.

The third type is the Inverter generator, nearly all (In fact all that I have ever heard of) are True Sine Wave, clean and pure.

I tried to find the article, Odds are your local library has it but I could not find the article with the searches I used.

But they covered the issues with a lot of the contractor models.

I have no problem with any of the electronics in the house on the Onan.. I tend to use caution with smaller generators though less they are Inverter type.

There is no way a non-inverter generator can produce a modified sine wave/modified square wave..

Distorted sine yes, modified no.

Norm Mac · 01-04-2013, 10:50 AM

Thanks everyone... I didn't realize my Onan was pure sine wave. I am used to portable gasoline gennies that we use when the power goes out. The critical electronics don't like them.
The icemaker in the home fridge died twice during power outages, I think the portable genny did it.

vermilye · 01-04-2013, 12:38 PM

Here is a link to a site that shows the waveforms of a couple of different AC devices.

wa8yxm · 01-04-2013, 02:26 PM

Good link can you find one for an Onan Emerald 5500?

NOTE: In the earlier post I said small portables generally have waveform issues.. (true)

I hope I mentioned that SOME of them are very clean as well. One I had (1KW) was rated Less than 3% distortion (Total Harmonic) and once it had "run in" it made my UPS boxes very happy,,, (New it did not).