I read somewhere that if you don't run a small generator every 6mos or so it loses its residual magnetic field and then won't generate electricity. I know enough about how a generator works that this has some basis in fact but am still slightly skeptical. At the risk of asking a dumb question, is this true? Asking because I don't want to find out my generator isn't when I really need it.
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David
The chief cause of failure in this life is giving up what you want most for what you want at the moment. -
Huh? Sounds like an old wives tale to me. Permanent magnets do not lose their field very readily and electromagnets are so called because their magnetic field is generated via an electric current. -
It was post #22 in this thread below:
http://www.bt3central.com/showthread...nerator&page=3
I'm with Jack, sounds kind of weird to me.
Allegedly it comes from Briggs and Stratton, you should be able to check it.
Loring in Katy, TX USA
If your only tool is a hammer, you tend to treat all problems as if they were nails.
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Beware - If your generator is working backwards it will creat a black hole just like that huge particle collider
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Surprised, but I guess it is for real:
http://en.wikipedia.org/wiki/Excitation_(magnetic)
Some links said newer generators had built-in circuits for this.Comment
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For wound field generators, there must be a voltage produced at startup so that the field winding can get current. Generating this voltage initially relies on the residual magnetic field in the stator. I have heard of cases where, when cars had DC generators, an external battery had to be momentarily connected to the system to get the generator going if the car battery was completely dead.
Tom on MarrowstoneComment
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Loring, thanks for the link but it wasn't that post. It was somewhere else. I will look into it somemore. Of course I could always just start my generator and make sure it works...David
The chief cause of failure in this life is giving up what you want most for what you want at the moment.Comment
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I had trouble with the link mentioned, but found this link:
http://en.wikipedia.org/wiki/Excitation_(magnetic)
The article addresses re-excitation in small generators.You might think I haven't contributed much to the world, but a large number
of the warning labels on tools can be traced back to things I've done...Comment
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The 2nd Wikipedia link didn't work either. I did some more rummaging and found the link. I think I will just call the manufacturer when I get home and ask them.David
The chief cause of failure in this life is giving up what you want most for what you want at the moment.Comment
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I did not say there was a link; there was text allegedly sourced by the B&S customer education dept.. That same text appears elsewhere with the same attribution to B&S. However, there is never a link to B&S, nor can I find by Googling any such article by B&S "customer education." Which means the article is either old and no longer hosted by B&S or its a outright hoax perpetuated by well-meaning multiple copies, or maybe a erronious act.
In any case, anyone can publish almost anything on the web, I'd take it with a grain of salt until I had proof from some more authoritative site.
OTOH, if you genset won't start, it doesn't sound like it can hurt to try.Loring in Katy, TX USA
If your only tool is a hammer, you tend to treat all problems as if they were nails.
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Generally speaking... most 'real' generators (ones with decent voltage control) have some sort of electronic excitation system that provides a DC field current to the armature windings. The poles may retain a certain amount of residual field strength after sustained use (kind of like the old school experiment about stroking a needle with a magnet enough times to make it become magnetized itself), but it will almost always be fairly weak. Fairly small generators may rely on a permanent magnet of some sort to provide the field strength necessary (these are known as permanent-magnet alternators); one example would be the alternator in your car. While they usually are lacking in power and control compared to a regularly excited generator, they do have a few significant advantages - the design is almost always simpler (no brushes or slip-rings required) and therefore tends to be more bullet/idiot-proof (little to no maintenance required, and not much that can break).
Some small generators that I've dealt with have had provisions for 'flashing' the field from a bank of small batteries (such as 6v lantern type) in an emergency. Once they get up and running - and generating voltage on their own, various feedback circuits can usually tap off the output terminal voltage and create the DC necessary to provide full field excitation control. On a number of these units (low rpm diesel gen sets with salient-pole generators), the pole pieces generally have enough mass and retain enough magnetism after a number of uses that field flashing was all but un-necessary. I'm not sure how well that would work on say, a high-speed wound-rotor turbine with far fewer pole pieces.
Keep in mind that in the world I work in, a 'small' generator is something under a couple megawatts in generating capacity. The specifics of consumer-grade portable generators might be somewhat different in the details.
MonteAll right, breaks over. Back on your heads!
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If that's the case, mine is junk. I think most people spend $800-$1000 on them and then they just sit. I always say that I think people should run generators only in emergencies. You'd be surprised how many people try and heat their homes using a generator for weeks at at time! Other tips for home safety and heating: Make sure to change the furnace filter, always make sure the wiring is checked regularly and never go more than a year without cleaning out your air ducts.Last edited by curtismay; 01-27-2012, 03:20 PM.Comment
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I have an older Homelite generator I bought 25 years ago (maybe longer). It is only 650 watts and have never had a problem with it. I use it perhaps once every 5-6 years and it has always provided good electrical service when I do need it. Odd thing is it always starts and runs on the first or second pull and I have NEVER winterized it for storage, etc.. Guess I just got a good one.
ConwaygolferComment
LCHIEN
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