Generators: Rated as 'clean power'. How can I tell and is there something to clean it

[RoyKing]

Standby Alternators | Hospital Alternator Manufactuers | Mecc Alte is good site to see the latest in genset design. I'm also a fan of the MEP 802A & MEP 803A the surplus tactical field genset from mil surplus. My latest install was rather serious 36kva with mecc ecp32 with digital voltage regulator and DeepSea 7200 line monitor controller running the 200A Generac transfer switch, in level 2 sound cabinet. However my personal needs are much smaller I'm using 6kw mil surplus I got from guy who buys them and rehabs them and he gave me a three warranty on parts. To me clean is how much noise on the sinewav and how much frequency and voltage fluctuation on starting large loads mainly the AC. Also from experience in bad situations get the fuel will be the problem, propane suppliers were overwhelmed, gas stations closed or dangerous to visit, so I made the choice of Diesel. 22 days of no power no phones and waiting in line armed for gas was an eye opener I don't want to repeat

 

[grsthegreat]

when i supplied clean power to computer rooms, there is a whole lot of things that go into effect besides just the supplied power. isolating transformer noise in lines, isolated grounds, etc.

All i know is my 22kw Generac powers my entire house. i have 2 whole house Siemens surge suppressors (FS140) one on house and one on shop panel. everything i own works great on generator power, all TV's, sound systems, computers, modern appliances, built in refers, etc. even my UPS devices have no issue with it.

 

[dragoneggs]

How to check for "clean power" simple. Just look at the waveform under a load with an oscilloscope. If it doesn't look like a sine wave, than it is not clean.

Most solar inverters are the antithesis of clean. Most produce square waves at best.

Is 'clean' power associated with a sine wave only. Can square wave be clean as well? I thought clean had to do with the 'jitteriness' of the signal. Now you know why I last one quarter in EE/CS before transferring to ME school.

 

[RoyKing]

switching power supplies give you square wave but they can be rounded off with more circuitry, clean has to do with lots of things, power factor, anything time you not on the sinewav would be consider noise, could also have higher frequency traveling along, over under shoots. When I was talking to a mecc alte support engineer he got into talking about how they wind the cores, and steel versus alum cores. Seems the alum cores can't handle the overload of lock rotor in rush. Ideally you want to be able to handle a 300% overload for 20 seconds, and life of the genset falls drastically after core gets hot enough to degrade the epoxy. If the exhaust vents look dusty it been run hot. So mean load should only be 60% of rated output.

 

[BrokenTrack]

Grounding has some to do with it as well.

I have always grounded everything, but a person on this site called me out on the practice and said that it can effect modern electronics. I looked into it, and he was right.

How much of an effect that is with "clean" power, I am not sure, but I found out, grounds have to be planned out, not just added whily-nily!

 

[Mark @ Everlast]

Clean is basically the ability of a generator to adhere to a true sine wave form (in our context), within 5%. The harmonic distortion, is the spikes, and overshoots, and stuff that can damage electronics.

I will tell you from my experience, that if a generator isn't advertised as clean, it isn't clean. But also we have found that there are a few we have found one or two that don't live up to their promises. Just saying...one is yellow and starts with "C". But for the value the Northern Tool Powerhorse line is great and clean. A newer one is the Ai power generators too.

But if it uses key words like "great for jobsites, emergency power, construction" it isn't going to be clean. If it uses words like " great for computers, electronics" or "can be used to run your new 3000.00 flat screen TV" it probably is clean, and will spell it out later in the information.

But if you don't see it say "clean" or safe for sensitive electronics, it isn't clean, pretty much guaranteed, unless the company is awful at marketing.

These days, all the name brands put out clean versions of their generators. Name brand, though, has nothing to do with being clean or not. Take generac for example. Clean? nope. Not in their basic lines. Anything in the GP line is pretty bad for electronics. But get into one of the models with an X in the number, IIRC, they are almost all clean, but double the price.

Then you go to lines like the PowerHorse, not a name brand, but a company brand from Northern tool, they are all rated that way, even their 27,000k unit.And a 1/3 of the price or less.

 

[RoyKing]

You mention grounding, there should only be one ground and everything route to it. Usually in the meter can or main breaker is where the neutral and ground are tied. Most ground stakes are not worth much, the clamp always loosens and corrodes and most are not down deep enough. Should be 20 ohms or less. Spend the $20 and buy the exothermic welder to connect the ground wire to the stake it welds it. You can find them on Ebay Pick the rod diameter and ground wire size. sand and clean then light it with propane torch and smash the pot with two hammers to inspect it. I always put 20 feet of rod down if I can. Also when installing transfer switch use that no loc stuff on all connections even if not using alum wire. I used a small brush and coat all the connection after I tighten them. It stops the corrioson of the alum buss bars and the screws from freezing up. Especially if it is in an exterior box.

 

[Industrial Toys]

I guess, "CLEAN" can mean different things to different people. To me, clean means the absense of noise (Interference and harmonics), apparently some generators are bad for harmonics. I can't comment on that as I don't know much about it.

Then there is the issue of not having pure sign waves. Many inverters make square waves electronicically, much cheaper to do than making pure sign. So I guess, people have taken pure and clean to mean the same thing. I would disagree.

 

[k0ua]

Is 'clean' power associated with a sine wave only. Can square wave be clean as well? I thought clean had to do with the 'jitteriness' of the signal. Now you know why I last one quarter in EE/CS before transferring to ME school.

The rapid leading edge of square waves produce transients. Many devices do not like these waveforms, not to mention all of the RFI that these waveforms generate and radiate.

 

[k0ua]

Take the average 12 VDC to 115 VAC inverter. These things produce RF energy from DC to Daylight. Just trashmasters. Just operate one, and then turn on a radio. You will find out real quick. Almost all of these devices generate square waves, NOT sine waves. Square waves are cheap and easy to generate, and by definition are BAD. At least bad for any kind of sensitive electronic device. They work fine for things without electronics as long as you don't attempt to operate a radio nearby. Sine waves are expensive and hard to generate. Follow the money.