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Author Topic: any suggestions on picking a gasoline power genera  (Read 13336 times)

KA3WXV

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any suggestions on picking a gasoline power genera
« on: October 05, 2001, 01:20:28 PM »

I would like to buy a portable generator 2500 to 5000 watts for the following purposes.
1. For running my sump pump (1/2 HP 120 VAC)when power fails 2.Field day or ARES/RACES activations.
3. To run my oil fired hot air furnace in the winter
if power fails.
I would plug the "appliances" directly into the generator. estimate 100 hours of service over the next 5 to 1o years.

Questions.
A. Do I buy cheap $500 or spend $1000 to $1600 for a medium priced unit.
B. What's a good way to judge the quality of the generator do I worry about harmonic distortion being 6% or less?  do I look for a Honda engine or is B&S
OK?

Whats the best way to ground the unit. Are the grounding requirements different when the generator is used in the field vs connected up to an oil fired heater in the house.

I realize this is a long question. It's really meant to start a good indepth discussion on this topic.I think most of us just "wing it". Probable NOT a good idea.  Also, are there any good books just on this subject?  Any comments?

George
KA3WXV

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KC7YRN

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any suggestions on picking a gasoline power genera
« Reply #1 on: October 05, 2001, 03:51:52 PM »

You're asking all the right questions. You can probably get better answers than these, but here's what I know.

The really cheap generators have a reputation for failing quickly if used for more than brief power outages.

Grounding the frame of the generator to nearby earth should be good. The last thing you want is a static spark when you're refueling. Bond it to your RF/lightning ground if you're plugging in radios.

Everyone I talk to enthusiastically pushes me to Honda engines, but let's face it, Briggs and Stratton engines are running a lot of reliable small equipment.

It sounds like you've already taken startup surges into account. That 1/2 hp motor takes less than 500 watts to run but may take from three to six times as much to start.

I don't know whether harmonic distortion really matters. Electronic equipment with switching power supplies should be pretty tolerant, other equipment might be touchier. Anyone have good information?

73 de KC7YRN Fred
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KB9YUR

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any suggestions on picking a gasoline power genera
« Reply #2 on: October 05, 2001, 09:05:05 PM »

Once you decide on a certain wattage, make sure the generator waveform is pure
sinewave, not modified sinewave. I currently own two Honda generators, one a 1000
watt unit and the other 3000 watts. They're the EU1000 and EU3000 models.
Some equipment will not work properly getting a modified sinewave waveform from the
generator (like most generators on the market), or may even overheat and burn out.
73
George ...
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KD7BCV

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any suggestions on picking a gasoline power genera
« Reply #3 on: October 08, 2001, 12:51:14 PM »

A few years ago, a wind storm took down power to our office.

We snagged a name brand 5kw generator from the local rental company and tried to run our file server and two or three workstations off it.

Using a medium sized UPS for power filtration, we could not get any power output.

To make a long story short, the engine was running at too low a speed so the generator was producing AC at less than 50 hz.  A friendly tech wandered by with an instrument that could detect the output frequency and adjusted the carburetor to increase the speed.

So, switching supplies can be sensitive to grossly misadjusted inputs.

Let's keep this thread going, I'll try to post an inteligent question, if I can.

73

KD7BCV
Chris P

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K3UOD

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any suggestions on picking a gasoline power genera
« Reply #4 on: October 08, 2001, 03:58:53 PM »

If you want to hook your house up to a generator you should really have a transfer panel.  I have a 10 circuit GenTran unit.  Easy to install and easy to use. Square D and Generac also make transer panels.

 Much safer than jury rigging.  Also eliminates the danger of backfeeding into the power line and possibly killing a power company lineman.  See the following link for a great step by step guide:

http://www.popularmechanics.com/home_improvement/home_improvement/1998/3/install_backup_generator/

I've also heard nothing but good about Honda generators and generators using Honda engines.  Built for continuous use and the quietest mufflers on the market.

Note:  If you have a well you may have to have a 240V generator to run the pump.
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N7UJB

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any suggestions on picking a gasoline power genera
« Reply #5 on: October 09, 2001, 02:29:21 PM »

Howdy,

I also use both of the higher end Honda generators, ( Eu3000 and Eu1000).

My shack is totally off grid, with the closest power lines more than a mile away.

The Eu3000 is usually run a few hours a day, to recharge my battery bank, when
the Western Wa. weather dosen't proviode enough sun, for the solar panels to do
their job.

The Eu series of generators are totally different in design, than the normal $500
to $900 generators. The EU series generates high current DC, which is then
converted to AC, using an excellent inverter.

The output is VERY clean, always regulated, and always 60.0 hertz.

The big advantages to this setup is that the engine speed is based on load, verses
the 3600 rpm used by all the other generators.

This makes it VERY quiet, STINGY on gas and little or no RFI......

Definalty worth the extra bucks !!!!!

DennisB
N7UJB
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KC7YRN

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any suggestions on picking a gasoline power genera
« Reply #6 on: October 09, 2001, 04:34:29 PM »

Wow, those look good! They have 12VDC output too -- are you using that? How clean is it?

Fascinating about the generator that wouldn't run a UPS.
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WA0ROX

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any suggestions on picking a gasoline power genera
« Reply #7 on: November 01, 2001, 01:24:29 PM »

UPS AND GENERATOR
here at work, we use a very large ups for our computer system, one day someone decided our big catterpiller 1.2 mw generator wasnt big enough, so since the ups was rated at 175kva, they bought a 175kva generator set to use on the computer ups. THere is one problem they found out about, the ups runs till the generator starts and switches in, then the generator has to power both the ups and the load till the batteries are charged up in the ups.  This causes a load  twice as large as the load to the computers for a while and the generator didnt work as expected. They should have read the book on the ups.
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W5HTW

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any suggestions on picking a gasoline power genera
« Reply #8 on: November 03, 2001, 08:13:09 PM »

Just thought I'd toss in some comments re my generator.  

I have an old Sears (Craftsman) 3500 gas generator which has served me well.  It can power the MFJ non-switching power supply cleanly, which then powers the 706 for emergency communications.  However, I use it mostly for powering the furnace and the refrigerator during power outages, which are very frequent here in the high desert of New Mexico on rural power.  It does both well.

But ... my household well is a 230 VAC pump, and I can not run anything else but the pump (and one working light) to fill my water tank.  Then with the tank full, I can disconnect the pump and switch back to the 230 VAC for the house.  The generator has one 230 VAC output, two 120 VAC outputs, and a 12 VDC output useful for powering small DC items, but this is not, I don't believe, good for powering 12 VDC digital radios, nor would it supply sufficient amperage for full power operation.  .  

I got the generator used, for the sole purpose of powering a 225 amp welder for portable welding work around the ranch.  It does that well at up to 180 amps on the welder but above that it starts to run quite hot.    And it runs hot at lower amperage if I weld very much extensively.

I ran it for a while during an 8-hour power outage, to keep my refrigerator running, and noticed the lights in the room were quite dim.  Tried the TV and saw vertical foldover.  Next day I checked the generator and found the AC output voltage was set at 92 VAC.  There is an adjustment, and I turned it up to 120 VAC (230 VAC AC) and it has been fine every since.  

Many generators have such adjustments.  Mine also has an automatic 'no-load idle" so that it drops down to an idle when the load is minimum, but even a 100 watt light bulb pushes it back to full speed.   That is convenient for long term power if you plan to take a nap and leave the generator running, but it won't power anything on low speed.   I found, too, at this altitude (over 6,000 feet) if it idles longer than about 5 minutes, then when the load switches on, it tends to flood, due probably to the carb being not correctly set for this altitude. (Or it could be a dusty air filter!)   One of these days I'll resolve that!.  

It runs the computer if I choose, with no noted problems.  It will run other ham rigs in the shack as well, but not with the amplifier, which would be a waste anyway.

It is a B&S engine, I believe 6 HP, OHV.  A good engine, far as I can tell.  

73
ed
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KD5IR

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any suggestions on picking a gasoline power genera
« Reply #9 on: November 22, 2001, 12:16:57 PM »

I purchased a generator from Northern tool about 18 months back. It is rated at 8000 watts surge and 6600 watts continuous---it will operate the following with no problem---2 std size ceiling fans , a medium frig-cycling on and off , 2 sets of neon lights with 3-40 watt bulbs ea. , 2 small window a\c units-and it will also power a 1hp. water well for 3~5 minutes until the pressure cuts the pump off at ~60 psi......this is probably about the max load given its rated load.  the generator has a 13 hp honda engine running at ~3750 rpm---noload---the noload voltage is abt 265 volts---as the load increases the voltage drops to about 120 volts at full load and the rpm will drop correspondingly----if you plugged a linear amp into the generator with no other load --the voltage would probably be too high--and fluctuate too much given the sensitivity of some of the more and expensive tubes in use in most modern amplifiers today...The other part of this story--involves the method that i use to feed the power into my breaker box---first I turn off my main breaker at the power pole outside my home---I live in the country so most residential homes won't be equipped in this fashion.....After I have turned off the breaker---I can plug a power cord from the generator into a 50 amp\240 volt wall receptacle that normally feeds my crackerbox welder---what this does is to feed the output of the generator BACKWARDS into the welder receptacle thru 2 20 amp breakers into the 200 amp  main breaker panel that feeds all the various electrical circuits in my home----it works very well---BUT---it is a potentially very dangerous method in that when the regular power comes back on you can really destroy your generator if your main breaker isn't turned off-----BUT , as long as you keep your electrical ducks quacking in the same direction all is well---those idiot proof panels that "everyone" should use are quite expensive--at least for my budget they are----this is just one method of interfacing a generator to your needs , kd5ir, sandy kuteman
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KD5IR

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any suggestions on picking a gasoline power genera
« Reply #10 on: November 22, 2001, 12:26:24 PM »

I need to clarify one sentence--I stated that the no load voltage was ~265 volts---that is true when measuring across both "hot wires" or it would be ~133 volts when measurng between the neutral and one hot lead--- obviously the voltage under load would drop from 133 down to 120 volts  , hope i didn't cornfuse anybody but myself , sandy kuteman  
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KD7PKO

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any suggestions on picking a gasoline power genera
« Reply #11 on: January 04, 2002, 09:30:00 PM »

I think this is an excellent topic for hams to discuss. Let me give some of my background, but please keep in mind I am not tyring to push any name brands or specific products here.

  My name is Chris Smith and I am a Power Generation Service Engineer with a diesel engine distributor in Sparks, NV. I have worked in and around two-way radios for most of my career. My father, W7HRY, is a long time ham and is thrilled I have joined in. My primary interest in ham radio is QRP and, you guessed it, power generation and the development of remote, off grid repeater sites.

  I think one of the best parts of being a ham will be exchanging info with other hams. Let's face it, I don't know squat about homebrew HF stuff but hope to learn alot from others. One thing I do know a fair amount about are generators and the related switchgear. I sure don't know it all,but I can probably find somebody in the industry to answer your question if I can't. BTW, everybody including me has an opinion and, one of those, and they both stink...

  I will try to stay on topic here as much as possible. If you have a specific question please e-mail me at nvhammerman@prodigy.net. In the interest of security please include your call in the header and avoid using attachments. I can then summarize the answer and post it here. Perhaps the folks at e-ham might consider this as a seperate topic in the future.

Now with the answers/more confusion:

  The fact is all small gasoline portable generators are pretty mediocre. Some are better than others, but they are few and far between. So lets compare some generator basics.

  First off, in the industry we call them "gensets" regardless of size or fuel. Secondly the equipment that actually connects the AC output to your stuff is called "switch-gear" (read in extension cord here!?!) so please excuse my use of jargon/lingo here.

  Gensets typically use 4 pole alternators or 2 pole alternators. 4 pole ones run at 1800 RPM and 2 pole units run at 3600 RPM. Generally, the faster an engine runs, the more fuel it uses, the more noise it makes and the sooner it wears out. Most small gas gensets run at 3600. This allows the use of small inexpensive engines. Manufacturers, including the company I work for, call this cost effective engineering... And they sell it as "lightweight, portable, inexpensive....." You know what I mean.

  Enter the world of 1800 RPM units. These gensets are usually stationary mounted and not very portable. They often are run on diesel fuel and can last for 15,000 to 20,000 hours of continuous duty. They are also very expensive.

  As a result most of us consumer types are left to choose from the gensets at Costco or Home Depot.

 "Great, Chris, I guess I'm just screwed now..."
Well, kind of, you just have to shop around to find the lesser of all evils.  

Shopping points:

  When it comes to the engine don't lose much sleep on the brand. Try to purchase one that has overhead valves (OHV) because they don't carbon up as bad.

  Be carefull of units that are "Powered by:" because you often pay for the engine makers name and wind up with an electrical end that is junk. Honda, Kawasaki, and most Japanese units are pretty good. Just for the record, I would not buy an Onan/Cummins portable based on the fact I have seen a lot of engine failures.( if my boss happens to read this I will be looking for a job...) If you are willing to spend a couple hundred bucks more at a local full service specialty shop ie: "Joe's Outdoor Power Equipment" you will probably have better luck than the box stores. Our buddy "Joe" will probably be willing to let you hear the genset run "UNDER FULL RATED LOAD" to compare noise levels. You just won't get that service at "the depot", sorry guys, stick with lumber.

Don't sweat what type of voltage regulation system the unit has. None of the portables use true automatic voltage regulators. Most use some type of capacitor system and cause radio noise, you get what you pay for...Look for units that offer some type of AC output voltage adjustment since these usually use a shunt type regulator versus capacitors.

For field day use or RV's, sizing of 3500 to 6000 watts will probably work OK. For just field day types of ops, get one of the ultra quiet "suitcase" units. 800-1000 watts will run most everything in the shack, with the exception of a 1500W amp of course!

For large club field day events, check with a local genset dealer or rental yard. They will be able to set you up with a 30kw or so unit to provide power to all the ops on site. Here's a hint, ask if they would be willing to donate use in the interest of serving the community. Most salesmen welcome the "free advertising" since the equipment just sits most of the time.

Regarding connection to your home for power outages:

  If you don't have the proper, code approved, and properly installed switchgear (transfer switch) DO NOT "RIG" IT UP. At best your genset will get burned up and you or someone else can be killed at worst. I won't go into anymore disertations here. Please post any questions. If somebody wants to run a UPS or large pump, please post your "load info" and I will try to help out.

The ARRL HANDBOOK has a pretty good section on AC theory that can be extrapolated for generator understanding. Also check out some of the independent power/off-grid/solar web sites. They usually offer some genset load calculation guidelines you can download. Just a word of caution: most of their "free advice" is geared to promoting their "product of the month" so ask them lots of tough questions about their products if you buy mail order.

 Thanks, and sorry for the "windy" post. Go see "Joe"
73, KD7PKO
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