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#1927799 - 06/19/10 12:14 PM 10kw 20hp generator rpm's?
05ChevyI5 Offline


Registered: 03/17/10
Posts: 247
Loc: NC
I've got a Honda powered(GX620)10kw generator. Honda specs the rpms@3400. Is this max rpms? So with a load I'll see less rpms?? I've set it up @3400 with a slight load. shrug

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#1927827 - 06/19/10 12:46 PM Re: 10kw 20hp generator rpm's? [Re: 05ChevyI5]
J. A. Rizzo Offline


Registered: 08/31/05
Posts: 477
Loc: Chicago, IL
The generator head is probably configured to give you 120v at 60Hz when the rotor turns at 3600 RPMs, so turning at 3400 probably gives you about 113.3 volts at 56.7 Hz. Most of these small generators don't have load-variable speed adjustment, so you have to sort of wing it with getting the voltage and frequency you need at the load level you expect. I run my GX390 at about 3780 RPMs with no load and it bogs down to about 3600 at about half load. That seems to work well to allow motors to start up and not see the lights flicker too much. What does Honda recommend as the maximum speed? And better yet, what oil are you using? :-)
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#1927829 - 06/19/10 12:47 PM Re: 10kw 20hp generator rpm's? [Re: 05ChevyI5]
05ChevyI5 Offline


Registered: 03/17/10
Posts: 247
Loc: NC
OOPS! Post correction. I set it up @3600 slight load.


Edited by 05ChevyI5 (06/19/10 12:55 PM)

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#1927832 - 06/19/10 12:48 PM Re: 10kw 20hp generator rpm's? [Re: J. A. Rizzo]
05ChevyI5 Offline


Registered: 03/17/10
Posts: 247
Loc: NC
Originally Posted By: J. A. Rizzo
The generator head is probably configured to give you 120v at 60Hz when the rotor turns at 3600 RPMs, so turning at 3400 probably gives you about 113.3 volts at 56.7 Hz. Most of these small generators don't have load-variable speed adjustment, so you have to sort of wing it with getting the voltage and frequency you need at the load level you expect. I run my GX390 at about 3780 RPMs with no load and it bogs down to about 3600 at about half load. That seems to work well to allow motors to start up and not see the lights flicker too much. What does Honda recommend as the maximum speed? And better yet, what oil are you using? :-)

3600. Amsoil HDD 5w-30.

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#1927837 - 06/19/10 12:57 PM Re: 10kw 20hp generator rpm's? [Re: 05ChevyI5]
daman Offline


Registered: 09/23/06
Posts: 10416
Loc: Bad Axe, MI
Here's a little info for ya i asked a wile ago when i had RPM concerns,since got it dialed in and alls well.


link
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#1927842 - 06/19/10 01:02 PM Re: 10kw 20hp generator rpm's? [Re: 05ChevyI5]
J. A. Rizzo Offline


Registered: 08/31/05
Posts: 477
Loc: Chicago, IL
Like I mentioned, I have mine set up to run at 3600 at 1/4 to 1/2 load, trying to keep the voltage and frequency close to normal to make sure things run right. At 3800 RPMs, the GX390 starts to misfire once in a while, so I have it set up to run about 3750-ish at no load and that seems to be about the right calibration. YMMV. What are you running with it? Backup for house power? Or are you running a specific load like a welder or power tools, etc.? I recommend a tachometer because things that are sensitive to voltage and frequency can be damaged if they're off kilter. If you run AC-powered clocks for a few hours, you may notice that their time is off after a while. They must run off the 60 Hz AC power frequency instead of an internal frequency source. My AC clocks used to run a few minutes slow after a few hours on generator, and that was because the generator originally was set up to run at 3600 RPMs at idle and it bogged down to 3400-ish at half load, so the frequency was low and the clock ran slower. My DC-powered clocks were all fine.
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#1927846 - 06/19/10 01:06 PM Re: 10kw 20hp generator rpm's? [Re: daman]
J. A. Rizzo Offline


Registered: 08/31/05
Posts: 477
Loc: Chicago, IL
Originally Posted By: daman
Here's a little info for ya i asked a wile ago when i had RPM concerns,since got it dialed in and alls well.


link


I put a small tachometer on mine to keep an eye on it. This one from Northern Tool works OK.

I would be more concerned about the frequency than the voltage.
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Tradition is nothing but an excuse to not be creative.

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#1927894 - 06/19/10 02:13 PM Re: 10kw 20hp generator rpm's? [Re: J. A. Rizzo]
JimPghPA Offline


Registered: 08/22/09
Posts: 2753
Loc: Pittsburgh,PA U.S.A.
Originally Posted By: J. A. Rizzo
Like I mentioned, I have mine set up to run at 3600 at 1/4 to 1/2 load, trying to keep the voltage and frequency close to normal to make sure things run right. At 3800 RPMs, the GX390 starts to misfire once in a while, so I have it set up to run about 3750-ish at no load and that seems to be about the right calibration. YMMV. What are you running with it? Backup for house power? Or are you running a specific load like a welder or power tools, etc.? I recommend a tachometer because things that are sensitive to voltage and frequency can be damaged if they're off kilter. If you run AC-powered clocks for a few hours, you may notice that their time is off after a while. They must run off the 60 Hz AC power frequency instead of an internal frequency source. My AC clocks used to run a few minutes slow after a few hours on generator, and that was because the generator originally was set up to run at 3600 RPMs at idle and it bogged down to 3400-ish at half load, so the frequency was low and the clock ran slower. My DC-powered clocks were all fine.


Either your governor or the governor sensitivity needs attention (adjusted or lubed), or it is a darn poor design.

Generators that run at 3600 RPM's should remain pretty much right on, at 3600 RPM regardless of load, 0 to 100 percent of rated. There are a few that sense 0 load and will cut the throttle back to a low rpm. But other than that, if it is a 3600 RPM design it should stay at 3600 RPM.

My cheepo Coleman Power Mate stays right at 3600 RPM now that I set the sensitivity on it properly. New, it was WAY out of adjustment.
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Boy will I be happy when ALL vehicles on public roads are autonomous.


JimPghPa


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#1928480 - 06/20/10 08:32 AM Re: 10kw 20hp generator rpm's? [Re: JimPghPA]
daman Offline


Registered: 09/23/06
Posts: 10416
Loc: Bad Axe, MI
Originally Posted By: JimPghPA
My cheepo Coleman Power Mate stays right at 3600 RPM now that I set the sensitivity on it properly. New, it was WAY out of adjustment.

Would you care to explain how that's done?
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#1929200 - 06/21/10 03:25 AM Re: 10kw 20hp generator rpm's? [Re: daman]
JimPghPA Offline


Registered: 08/22/09
Posts: 2753
Loc: Pittsburgh,PA U.S.A.
Originally Posted By: daman
Originally Posted By: JimPghPA
My cheepo Coleman Power Mate stays right at 3600 RPM now that I set the sensitivity on it properly. New, it was WAY out of adjustment.

Would you care to explain how that's done?


It has been a while since I did this.

My Coleman Powermate 5000 /6250 has a 10 HP Tecumseh HM on it. If it were a B&S or some other brand of engine the governor and sensitivity would probably be a different set-up.

Be sure the air cleaner, and spark plug are clean, and the spark plug is set properly.

USE EAR PROTECTION (PREFERABLY BOTH PLUGS AND MUFFS). I CAN NOT EMPHASIZE THIS ENOUGH. THESE ENGINES WILL DAMAGE YOUR HEARING WITHOUT EAR PROTECTION.

First, with the engine warmed up and generator loaded to 1/2 rated (I use electric heaters) set the RPM's to 3600.

There are several ways to do this. I used a frequency meter. You could use a tack, but you would require access to the end of a shaft. Or you could use an analog alarm clock that runs on 120 AC. Compare the second hand to a battery powered clock. The second hand on the AC clock will vary according to if the RPM's are high, right on, or low.

After you set the RPM's there is a long lever arm made of two pieces of metal with a screw part way along it to adjust (this is the sensitivity adjustment). Shut the engine off and let it cool so you do not get burnt. If you loosen that screw and change the angle of how the two arms align you are actually changing the amount the spring has to pull on it to get the carb throttle plate to the same position. There is a sweet spot where the spring with the amount of stretch it will be at will give good response through-out the entire load range.

You may have to re-adjust the RPM setting after you change the lever arms alignment to get it back to 3600. If you get the lever arm right, the idle and load RPM's will be steady at 3600.

If your engine requires adjustment of the sensitivity you will probably notice the engine hunting in RPM's at some range of the throttle such as idle or light load.

BTW: I spoke to a mechanic who works on these generators and he said that in general they come from the factory set at an RPM above 3600. And running them even a little above 3600 for long times is very hard on them, and shortens their life. So set the RPM to exactly 3600 at 1/2 load.

Again it has been a while since I did this, but looking at the set-up on the engine on my generator this is what I remember.

Remember the angle the arms were at before you change them in case you have to change them back. You could scribe a short line that shows how they align right now.


Edited by JimPghPA (06/21/10 03:27 AM)
_________________________
Boy will I be happy when ALL vehicles on public roads are autonomous.


JimPghPa


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#1929285 - 06/21/10 08:50 AM Re: 10kw 20hp generator rpm's? [Re: JimPghPA]
boraticus Offline


Registered: 04/19/09
Posts: 2533
Loc: Canada
I'd use an electronic tach that runs off a spark plug lead. Very accurate.

Setting the RPM on my diesel power plant isn't difficult to do but reading the rpms is. No spark plugs means my electronic tach won't work on it. I had to buy a Treysit Sirometer to read the engine speed. I was skeptical at first on how well it would measure the rpms but it's pretty accurate! My gen set runs at 1800 rpm. The electrical frequency is very important. Voltage can vary with little effect. I was speaking to an electrician yesterday and he told me that most 115 volt devices will run on anything from 110 to 130 with no ill effects. Improper frequency on the other hand can play havoc on all sorts of things.

As per previous recommendations, set the engine to run at 3600 rpm under normal loads.

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#1929305 - 06/21/10 09:18 AM Re: 10kw 20hp generator rpm's? [Re: boraticus]
meep Offline


Registered: 02/20/07
Posts: 2395
Loc: Southeast
you would rather have the frequency above 60 than below. lower frequency runs the risk of magnetic saturation in motors, transformers -- meaning that coil of wire starts to become a short and overheats. Undervoltage does the same thing, just from the other end of the equation, which is why brownouts burn out compressors.

Mikey
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2006 Tundra 2wd
2002 MDX (wifey!)
2003 town and country, in various state of repair

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#1929840 - 06/21/10 07:51 PM Re: 10kw 20hp generator rpm's? [Re: meep]
JimPghPA Offline


Registered: 08/22/09
Posts: 2753
Loc: Pittsburgh,PA U.S.A.
Higher RPMs are tough on the engine.
_________________________
Boy will I be happy when ALL vehicles on public roads are autonomous.


JimPghPa


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#1931479 - 06/23/10 08:49 AM Re: 10kw 20hp generator rpm's? [Re: JimPghPA]
meep Offline


Registered: 02/20/07
Posts: 2395
Loc: Southeast
Originally Posted By: JimPghPA
Higher RPMs are tough on the engine.


yeah... i bought a robin-subaru motor a couple years back. it was rated 6.5 hp at 4400 rpm. but it's max sustained rpm was 3600.

that genset MUST be able to maintain 3600 to prevent damage to electrical equipment.
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2006 Tundra 2wd
2002 MDX (wifey!)
2003 town and country, in various state of repair

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#1931536 - 06/23/10 09:36 AM Re: 10kw 20hp generator rpm's? [Re: meep]
scurvy Offline


Registered: 02/19/07
Posts: 2243
Loc: Chicago IL USA
For a frequency meter, my Fluke 76 RMS multimeter is very handy indeed, but a more field-expedient solution would be a Kill-A-Watt unit. Incredibly handy to have around the house.
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