Dirty Genset Power - What works, what doesnt

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  #1  
Old 12-07-12, 07:33 AM
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Dirty Genset Power - What works, what doesnt

Sparkies -

In your opinion, with the contractor style grade/portable NON inverter gensets out there, what generally DOES not work with these *somewhat Dirty Power* gensets.

I have a Guardian for my secondary residence on a auto transfer switch.

For my primary, I have 2 EU Inverter Based Gensets.

I want to add a 120/240 Portable genset to the mix.

From what I have seen and know, alot of my friends have been using any joe-blow fine and it works for their tv, fridge, etc...


I've read and heard that modern Electronics just doesn't like dirty power.
This sorta contradicts with the results of people out there using the portable gensets with success. The only downside that I have seen blurbs about are applicance stores selling *more appliances* due to apparently gensets making fridges go bad.

I'd be curious to hear what you guys see out in the field ?
 
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  #2  
Old 12-07-12, 07:57 AM
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I've never had a problem with my UPS on generator power. Only if a heavy load kicks on will I momentarily hear a click, and then it clicks back to generator power. if they even like the power, I guess there's nothing wrong with the power.
 
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Old 12-07-12, 08:09 AM
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Have had and used many by different manufacturers in the 4KW and up power range without problems. We use them to run emergency communications trailers as well as jobsite tools. I think your worries are unfounded.
 
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Old 12-07-12, 08:27 AM
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Most/all modern electronics I've tried have worked quite well with an old fashioned mechanical generator. Computers, microwave, TV's, stove all worked without any sign of problem. Surprisingly it was plain incandescent light bulbs that would flicker with the minor frequency variation that my generator was putting out.
 
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Old 12-07-12, 08:40 AM
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IMO if you monitor the generators output and maintain 60hz you should have no issue running anything.

A simple kill o watt meter will accomplish that.

It comes down to the gens ability to maintain 60hz. Some are better some are not. It really comes down to your loads.

If you are running sensitive electronics, then try to start say a well pump, the voltage and hz will drop until the gen governor can recover. ( Thats a standard gen)

The AVR and inverter types overcome this fluctuation by using electrical means to keep the power stable.

What I do for an example is shut down all electronic loads when starting the well pump. Everyone showers etc then I turn the well pump breaker off. I then run the rest of the home, lights ,tvs, computers, fridge, maintaining a constant 60 hz.

My well pump is the only thing that will pull my mechanical governor gen power down briefly until the motor starts.

All homes are different on what they need to power so there are many variables on what gen is needed.

I am able to monitor but some people do not what the hassle or do not understand. Yes a AVR or inverter gen will keep a more constant 60hz but you have to pay the price.

IMO there is no dirty power. Its just the gens ability to maintain that 60hz. Motor size on a standard gen can overcome that in most cases, but you pay a price in fuel usage.

Not an electrician but just my take on the whole thing.
 
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Old 12-07-12, 02:14 PM
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Is it really just that simple...the ability of the Genset to keep up with the RPM's.
Interesting...

I would have though copper vs. alum. windings on the alt - and or I'm not sure how much the circuit/panel board plays a role with a regular good 'ole portable contractor style genset.
 
  #7  
Old 12-07-12, 05:34 PM
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It depends on the product and how it was designed. Some generators put out better power than other. I don't know how much damage could be done, but sometimes the appliance just won't work if the power isn't any good. If you can find a generator that has the total harmonic distortion (THD) spec'd and it is less than 6%, you are good to go.
 
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Old 12-08-12, 09:07 AM
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Other than old AC-powered synchronous-motor clocks, what devices "care" about the power frequency? These days almost everything has an input rating of "120V 50/60Hz" so frequency isn't critical for those devices. Certainly anything that internally runs off DC power won't be affected by poor frequency (and to some degree voltage) limits.

I realize your furnace blower and refrigerant compressors will not run at their rated speed--but does some slight variation matter at all?
 
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Old 12-08-12, 02:30 PM
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I ended up with a no-name (or at least one I've never heard of) generator last month. It ran the appliances and computers just fine. One UPS ran fine on it, the other (older) UPS kept switching on and off battery every couple seconds. I attributed it to dirty power, and an old UPS. I unplugged the UPS and plugged my computer directly into the generator and all was fine.

Personally, as long as the generator is putting out 120v, I'm not all that worried.
 
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Old 12-08-12, 02:40 PM
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I'm not an expert and am just repeating what I have heard from people more knowledgeable about said topic. For electronics, it all depends on how the power supply is designed. Well designed units won't have an issue. There could be components that don't like imperfect sine waves. Just like Zorfdt, I plugged my UPS into a brand new generator and it wouldn't use it. I plugged my pc directly in and it worked fine with no issues.
 
  #11  
Old 12-08-12, 02:50 PM
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I found this page: Power quality from various backup devices

He ha sposted several pictures of sine waves form different sources. There are sine waves from the grid, UPS batteries, inverter generators, and regular generators. The grid ones are nice as are some of the UPS. The cheaper UPS products put out modified sine waves which are square. At the bottom he has an example of sine waves from a cheap generator. From those pics, you can see what is meant by dirty power.

I was led to that link from this page about appliances and generators: Can Portable Generators Damage Home Appliances?
 
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Old 12-08-12, 06:15 PM
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That's an interesting article and shows the output from several inverters. The author seems to be more concerned with inverters & UPS's as unfortunately he only showed one cheap no-brand generator--and he doesn't even say if it's an inverter generator or a standard one.

I wish he had done more testing on generators, including inverter-output ones. I'm very curious to know if the "pure sine" inverter generators really are any cleaner than a cheap synchronous generator. High quality inverters like those sold for marine use cost far more than the inverter generators so I'm assuming there are some trade-offs in quality since the engine. fuel tank, alternator and frame do probably cost more than the inverter box.

I need to find a friend or neighbor with an inverter generator who'll let me do some testing. These are my 'scope shots of my $300 Wen 3500 watt regular generator (since replaced by a Champion 3500W with the same engine & generator but capable of delivering the full rated watts at 120V). The no-load output is "fuzzy" but way better than the one in the article.

 
  #13  
Old 12-09-12, 05:53 AM
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He does test an inverter generator. It was the Honda GU200i. It's abotu half way down the page.
 
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Old 12-09-12, 05:57 AM
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The article does say that the generator tested is a Honda EU2000i
 
  #15  
Old 12-09-12, 06:22 AM
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Oops! Sorry. I don't know how I got that screwed up.
 
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Old 12-09-12, 08:01 PM
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My bad. .
 
  #17  
Old 12-10-12, 05:27 PM
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These are my 'scope shots of my $300 Wen 3500 watt regular generator (since replaced by a Champion 3500W with the same engine & generator but capable of delivering the full rated watts at 120V).
Would that be one of the 8,600 recalled Champion generators that were sold at Costco? I read just today they were recalled due to fuel leaks.
 
  #18  
Old 12-10-12, 09:35 PM
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No...mine is older and has a good carb float...one of the 100,000 NOT sold at Costco
 
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