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Generators & Electric Motors General Discussion Antique Generators and Old Electric Motors: Questions and answers about restoring and showing old power generation systems.

Generators & Electric Motors General Discussion

general question about Generator


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  #1  
Old 07-17-2012, 04:16:23 PM
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Andrew Albrecht Andrew Albrecht is offline
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Default general question about Generator

If i generator is back fed from the utility co. will it mess up the generator?
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Old 07-17-2012, 04:22:49 PM
Douglas123 Douglas123 is offline
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Default Re: general question about Generator

Probably will. Did you see any magic smoke!!
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Old 07-17-2012, 04:41:11 PM
Isaac-1 Isaac-1 is offline
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Default Re: general question about Generator

Chances are it will, but it also serves anyone right that was back feeding a utility line. Back feeding can kill linemen that are trying to restore power, most people seem to think what is the big deal about a little shock from a generator, well even on a direct connection a little shock can be fatal, however for linemen working on powerlines that generator is back feeding through the supply transformer and stepping up to several thousand volts which is a lot worse than a 120V shock.

Ike
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Old 07-17-2012, 04:45:09 PM
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Default Re: general question about Generator

no. i am asking because a coworker has a neighbor with a 5000 or 6500 gen. for sale cheap. he had it on when power came back on, and he wasn't home. now no output. just wondering if its fixable?

WOW never thought about it that way. when i ran my small one the other week i just ran an exstention cord to the frig. I guess that why they make transfer switches.
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Old 07-17-2012, 05:05:56 PM
Isaac-1 Isaac-1 is offline
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Default Re: general question about Generator

It depends on the generator design, if it has a voltage regulator (even one of those little capacitor types) it may have just cooked the voltage regulator or even the output breaker, if on the other hand it was a simple unregulated generator most likely the output windings are cooked. I would not spend any more than scrap metal value on it personally, well to tell the truth I would not do even that as even if you fix it you only have a cheap consumer generator.

Ike
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Old 07-17-2012, 05:20:37 PM
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Default Re: general question about Generator

Thanks. i will check into it more before i buy it. He did say it was one of the better name brands. and for my once a yr use it would be fine. Plus i like the challenge of fixing something.
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Old 07-17-2012, 05:38:25 PM
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Talking Re: general question about Generator

Andrew, when you et close, do a "Sniff Test"..... if you smell "Burnt" leave it where it sits, and walk away.....
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  #8  
Old 07-17-2012, 05:46:04 PM
Isaac-1 Isaac-1 is offline
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Default Re: general question about Generator

The sad thing is most of the "better" brand names are nothing more than the cheap made in China junk with a different paint job. About the only portable consumer brand models I consider better would be ones built by Honda or Yamaha. Stay away from Generac, they spend all their money on advertising to convince people they are not junk.

Ike
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Old 07-17-2012, 05:51:14 PM
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Default Re: general question about Generator

Ok thanks guys. My other post is where i did pick up a generac and have questions there. But the good thing is i only payed $49.00 for it. I got it running but just want to check and make sure the last guy didn't turn screws all over the place, if ya know what i mean.
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Old 07-17-2012, 09:47:38 PM
Graycenphil Graycenphil is offline
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Default Re: general question about Generator

Quote:
Originally Posted by Andrew Albrecht View Post
no. i am asking because a coworker has a neighbor with a 5000 or 6500 gen. for sale cheap. he had it on when power came back on, and he wasn't home.
If you do get it, you should point out to him that what he did was illegal and dangerous. It seems he left home with the generator running, conected to the house, and the house still connected to the utility. If instead of turning on the power, a lineman had been working on the other side of his transformer, he could have been electrocuted.
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Old 07-17-2012, 10:10:18 PM
dougreig dougreig is offline
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Default Re: general question about Generator

Yes. I know someone that it happened to.
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Old 07-17-2012, 10:21:01 PM
dougreig dougreig is offline
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Default MEP-003A wiring issue

I purchased a Mep-003A from an auction. I bought the generator "sight unseen". The generator came with the wires that come out of the generator motor were cut and removed. I have purchased a new wiring harness for the generator. But, I cannot read the numbers on the 10 short wires coming out of the generator motor. Would anyone know if the wires coming out of the gen motor that are placed in the rubber isolator in a standard sequence? If so, I would like to know how to find out the sequence is laid out in the rubber isolator. Can anyone help with that? I have attached a pics of the issue. Thanks in advance.
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Old 07-18-2012, 06:20:43 AM
armandh armandh is offline
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Default Re: general question about Generator

if there is a wiring diagram a little work with a volt/ohm meter should sort things out.
there appears to be 10 heavy and 2 light gauge wires
the heaviest wires are likely the output [stator]
this suggests a hi/low Y configuration

6 of the wires will show continuity in pairs
mark them as such pairs

the remaining 4 should show continuity and one of them [T0]
should read the lowest resistance equally to the other 3

what pair goes with what phase of the fixed Y needs to wait until the generator is operating

with the loose pairs wired in a Y with the T0 all connected
but the hot ends [6 of them] not connected
feed a test excitation voltage and with the engine running

all 6 should be near the same voltage to T0
call it the test out put voltage
then
measure between the 6 leads

there are 4 possible states HI, med HI, LOW, near zero

near zero indicates the correct phasing for parallel [don't do it yet]
highest, 2 times the test voltage, indicates correct phase but the pair is 180 degrees out of phase
swap the two ends of the pair and retest. a hi or low mid voltage indicates a wrong phase relationship

only swap one pair ends and re test at a time as it can get confusing
in the end you will have low Y Identified
as to which is the a,b,or c phase it is arbitrary

if you have no clue to the safety measures needed working around LETHAL voltages get professional help please!
I am assuming it is not a 400 Hz unit and thus a waste of time.

Last edited by armandh; 07-18-2012 at 06:46:17 AM.
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  #14  
Old 07-18-2012, 07:45:56 AM
Kevin K Kevin K is offline
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Default Re: MEP-003A wiring issue

Quote:
Originally Posted by dougreig View Post
I purchased a Mep-003A from an auction. I bought the generator "sight unseen".
Unless you paid scrap metal price - what you would get if you hauled it to the junkyard - or less, that's a terrible way to buy a generator. It's always what you don't know that will bite you.

You can pick up manuals here:
http://www.greenmountaingenerators.c...d-support.html

And here:
http://igor.chudov.com/manuals/Milit...tors/MEP-003A/
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Old 07-18-2012, 08:50:20 AM
Isaac-1 Isaac-1 is offline
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Default Re: general question about Generator

Kevin, it can also be a great way to get a deal, over the last few years I have bought 5 or 6 generators from GL auctions and in most cases made my purchase decision based on some low resolution auction photos, so far all have needed some minor to moderate work to get running, but were still great bargins. How else do you buy something like a 30KW Kohler FR-II diesel for $1,200 (plus another $300 or so and a few hours of time to get running), this is not exactly scrap metal pricing, but not anywhere near retail value either.

Ike
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Old 07-18-2012, 01:27:43 PM
Kevin K Kevin K is offline
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Default Re: general question about Generator

Isaac, what you say about getting a good deal is true. But don't forget that you used your considerable knowledge, skills, and time to turn a non-functioning lump of iron into a fully functioning generator. Not everyone has the ability to do that. If the original poster had the necessary skills to be playing the "buy sight unseen" game, he would not be on the forum asking such a simple question. If you don't have considerable experience with the equipment you are buying, the outcome is almost always better if you wait for a fully functional, tested unit to become available and make the seller a reasonable offer.

A great way to get the necessary experience is to pick up a couple of units for scrap pricing. When you're done playing, you can get most of your money back by making a trip to the scrap yard. Once you've "Paid Your Dues", become familiar with the equipment, and know what to look for, you can begin to think about playing the auction game. It's what you don't know that will bite you. For example, there are a couple of 10Kw MEP's on CL locally with 400Hz heads that the seller wants about $3000 each for. Good luck! You can only suppose that he bought them without knowing what they were, and now he's trying to pawn them off on someone else.
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Old 07-18-2012, 01:47:35 PM
grif grif is offline
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Default Re: general question about Generator

I think one thing missing in a lot of the "What's it Worth" threads is a total lack of recognition of the difference between hobby, and "other".

A hobby machine might be really good looking, with a toasted gen head but a good engine and control section, really worth only scrap, but as a hobby machine, can give somebody like me hours of non-alcoholic bar time fun, and a lot of good experience for later acquisitions, that may be more appropriate as a live backup unit, or a flip unit for profit. A machine picked up at auction for actual use, or sell for profit is a whole different animal.
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Old 07-19-2012, 11:45:50 PM
Seafarer12 Seafarer12 is offline
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Default Re: general question about Generator

Grif,
You got that right. It probably has a 10 hp engine on it. Perfect gocart material.

As far as back feeding a little generator it is probably toast. For one thing when the power came back on it would force that little generator to sync up to the grid. Either speed up or slow down, not good on equipment. Then when it ran out of fuel it would try to motor till something took it out and tripped something. We call that reverse power, also not good.
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Old 07-20-2012, 05:09:35 PM
Ken86gt Ken86gt is offline
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Default Re: general question about Generator

Going back to the original question- I doubt that a small generator would have lasted any length of time trying to back feed the utility while the power was out. So, I suspect that the generate was not ever back feeding the utility in the first place and that the generator is fine. Have you tested it?
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