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Portable Generator Power Quality Questions

Fusionstate

Fusionstate

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Nov 24, 2023
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Couldn't find a specific forum for this question. For my application, it doesn't apply to HAM Radio operations, but I figured, Y'all know something about RF noise, so here goes.

What are the opinions regarding the quality of power the portable generators make; I have a Firman 3500- How much RF do they generate; And is it harmful to computers? I'm considering adding a filter like this to the output of the genny: https://www.amazon.com/dp/B016EJ5DU2?tag=worradfor-20

I've seen some videos of scope shots on youtube and the sinusoidal portion looks approximate enough, however, there is some RF surfing on the waveform.

Regards.
 

If you're running expensive radio gear you need to run what's known as an "inverter generator" as these put out a perfect 60 Hz sinewave.
If it doesn't say "Honda" on the case, don't buy it.
My Honda inverter generator generates no RF interference whatsoever. Other brands can be very noisy with RF junk.

That's my two cents worth of generator advice, having lived off-grid for parts of my life !
 
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Fusionstate said:
Couldn't find a specific forum for this question. For my application, it doesn't apply to HAM Radio operations, but I figured, Y'all know something about RF noise, so here goes.

What are the opinions regarding the quality of power the portable generators make; I have a Firman 3500- How much RF do they generate; And is it harmful to computers? I'm considering adding a filter like this to the output of the genny: https://www.amazon.com/dp/B016EJ5DU2?tag=worradfor-20

I've seen some videos of scope shots on youtube and the sinusoidal portion looks approximate enough, however, there is some RF surfing on the waveform.

Regards.
Click to expand...
The criteria for HF radio and generators and computers are as you know, stability and RFI. What affects the these factors are a few things. Generator head windings, spark plug/boot type and any control electronics. The Firman's are not great for stability/clean waveform. They are cost cut generator heads, that do not have good windings. The total harmonic distortion of a Firman, depending on who you ask, is typically greater than 20%. For stability and cleaner sine wave, I would get a generator with 5% or better and be sure it is using a resistor plug or has a resistor spark plug boot.

In respect to inverter types, they tend to generate RFI, more so than the rotor/stator traditional gen head. As BC Coyote said, the Honda's are generally cleaner. But they cost like 5x as much as a Chinese clone.

73,

SL
 
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SuperLid said:
The criteria for HF radio and generators and computers are as you know, stability and RFI. What affects the these factors are a few things. Generator head windings, spark plug/boot type and any control electronics. The Firman's are not great for stability/clean waveform. They are cost cut generator heads, that do not have good windings. The total harmonic distortion of a Firman, depending on who you ask, is typically greater than 20%. For stability and cleaner sine wave, I would get a generator with 5% or better and be sure it is using a resistor plug or has a resistor spark plug boot.

In respect to inverter types, they tend to generate RFI, more so than the rotor/stator traditional gen head. As BC Coyote said, the Honda's are generally cleaner. But they cost like 5x as much as a Chinese clone.

73,

SL
Click to expand...
Thanks.

So will adding an EMI filter improve the harmonic distortion rating?
 
BC Coyote said:
If you're running expensive radio gear you need to run what's known as an "inverter generator" as these put out a perfect 60 Hz sinewave.
If it doesn't say "Honda" on the case, don't buy it.
My Honda inverter generator generates no RF interference whatsoever. Other brands can be very noisy with RF junk.

That's my two cents worth of generator advice, having lived off-grid for parts of my life !
Click to expand...
Agreed. I’ve had a Honda 2200i inverter since 2008, superb power inverter. I can run my furnace, a tv, and three 75 watt light bulbs no problem. Since it only has a one gallon tank you do have to gas up every 4-5 hours. Where it really shines is powering sensitive electronics.
 
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SuperLid said:
But they cost like 5x as much as a Chinese clone.
Click to expand...
They cost 5 times as much as a Chinese clone, and last at least 8 to 10 times longer, so it is much more economical in the long run to just buy the Honda.
You will also save yourself a ton of aggravation by buying a Honda instead of a Chinese clone. And as a bonus your house and/or shop likely won't burn to the ground if you run a Honda.
 
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I have never had a problem with my generator. I know the waveform looks pretty clean but honestly never really looked at it REAL close, mostly because I never had a problem. The brand is a Wallenstein, made in Ontario Canada. It uses an Italian made alternator unit driven by a 13 hp Honda engine and makes 7200w peak/ 6500 watts continuous. I looked up the name on the alternator to get some info and found out it was actually made by a very reputable company that makes everything from small standby units to massive industrial generator units. That combo was pretty pricey but has given GREAT performance over the many years I have had it. The only issue I have had was a sticky governor linkage that would not allow the engine speed to come up to what it should be. Five minutes and a shot of WD-40 took care of that. Sure I could have bought a Champion brand with supposedly higher output for less than half the price, but I fully believe this is a case of you get what you pay for. Oh......after a whole year of non-use it started on the second pull.........I forgot to turn the switch on first. LOL The battery died long ago and I just never replaced it.
 
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Captain Kilowatt said:
I have never had a problem with my generator. I know the waveform looks pretty clean but honestly never really looked at it REAL close, mostly because I never had a problem. The brand is a Wallenstein, made in Ontario Canada. It uses an Italian made alternator unit driven by a 13 hp Honda engine and makes 7200w peak/ 6500 watts continuous. I looked up the name on the alternator to get some info and found out it was actually made by a very reputable company that makes everything from small standby units to massive industrial generator units. That combo was pretty pricey but has given GREAT performance over the many years I have had it. The only issue I have had was a sticky governor linkage that would not allow the engine speed to come up to what it should be. Five minutes and a shot of WD-40 took care of that. Sure I could have bought a Champion brand with supposedly higher output for less than half the price, but I fully believe this is a case of you get what you pay for. Oh......after a whole year of non-use it started on the second pull.........I forgot to turn the switch on first. LOL The battery died long ago and I just never replaced it.
Click to expand...
What you have, sounds like a high quality unit, without a doubt. The Champion units are actually one of the better Chinese clones. They do have a 5% THD alternator and have overvoltage protection, in the event of a high going AVR failure.
 
BC Coyote said:
They cost 5 times as much as a Chinese clone, and last at least 8 to 10 times longer, so it is much more economical in the long run to just buy the Honda.
You will also save yourself a ton of aggravation by buying a Honda instead of a Chinese clone. And as a bonus your house and/or shop likely won't burn to the ground if you run a Honda.
Click to expand...
I think the Chinese generators are reliable. But the inverters are not clean like a Honda. You can't go wrong with a real Honda, they just cost a lot more. I have several gensets from US, China and one Honda. The Honda cost $1600 and the Chonda was $400. The backup beast, is a US made Briggs with a 16 HP Intek engine. That genny laughs at the loads I throw at it.
 
I also have a Generac GP5500, it’s loud but it’s a beast of a generator. Generac also now has a line of inverters similar to the Honda’s. Have not really checked them out.
 
SuperLid said:
No
Click to expand...
The above answer was to the question: So will adding an EMI filter reduce the harmonic distortion?

Well, I just went and did some research on THD and the Firman THD level. It's been a while so in researching THD, I see why now, the answer to the question is, No.

I'm believing the distortion to the 60 hz sine wave has already occurred in the generator, due to the, what, Trigonometry and phase influences of the nth order harmonics.

And, , , In reading the Firman manual, it states the THD is, Standard. Okay, what is a Standard level of THD. Turns out it's, 25%

To me that sounds like bad for switching power supplies and other electronics.
 
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Fusionstate said:
The above answer was to the question: So will adding an EMI filter reduce the harmonic distortion?

Well, I just went and did some research on THD and the Firman THD level. It's been a while so in researching THD, I see why now, the answer to the question is, No.

I'm believing the distortion to the 60 hz sine wave has already occurred in the generator, due to the, what, Trigonometry and phase influences of the nth order harmonics.

And, , , In reading the Firman manual, it states the THD is, Standard. Okay, what is a Standard level of THD. Turns out it's, 25%

To me that sounds like bad for switching power supplies and other electronics.
Click to expand...
Yes, to all of that. I was surprised that Firman would sell something that poor, but they do. I would not but one myself.
 
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At some point I'm going to put an old BK 5 Mhz scope on the output, under load to get an idea as to the power quality.

However, I recall, back in the early 80's, I wanted to look at some signals on the main board of a laser scanner. When I touched a component with the scope probe, it blew the fuse in the scanner. Had something to do with the grounding between the scope and the scanner.

How likely is it, that probing the output of the genny will blow a fuse or something if I plug the scope into the generator output and then probe the same power source? Seems as though it should be fine.

Regards.
 

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