MEP018 10KW generator head availability

[bjornb]

After running beautifully a total of some 25 hours last fall, my generator failed with two windings shorted. Last week I found a cannibalized mep018 set, but it too had two windings shorted.
I don't think I have the expertise and/or tools needed to repair either one of these and joined your group today to see if any of you know if there are any good 10KW/60Hz/3,600 rpm generator heads to be had.
I'm in Virginia and, obviously, the price has to be right.
TIA

Bjorn

[nehog]

It wasn't the same two winding shorted, was it?

[bjornb]

Originally Posted by nehog

It wasn't the same two winding shorted, was it?

No, on my generator, windings T2-T5 and T8-T11 were shorted. The generator was set up for "split phase" operation to power the house. On the replacement I got, the T3-T6 and T9-T12 were shorted.

[bjornb]

Here are a couple of images of my MEP018 as it's mounted on the '69 xm757. In service, a 400Hz generator (MEP023A) was used to power the Pershing 1A that was hauled by this vehicle.

[nehog]

I wish you were closer... I'd love to take a look at the two heads, experience tells me that of the two, possibly one would be repairable...

[bjornb]

Originally Posted by nehog

I wish you were closer... I'd love to take a look at the two heads, experience tells me that of the two, possibly one would be repairable...

This is the replacement I have, I'll be attempting to take it apart for practice, since my original is in better shape and have nothing to lose, it will come apart later. Just don't know about fixing a short if it's within the stator winding...

[nehog]

Originally Posted by bjornb

... Just don't know about fixing a short if it's within the stator winding...

If the short is in the winding itself, it is virtually impossible to 'fix', you need to rewind. Rewinding a coil is not difficult however, and at least for the MEP-004, the manual covers rewinding the coils. There are a lot of old books on rewinding motors (the process for a generator head is identical) and probably some online too. Look for one of the Audels books for example. I may have a book here, but I don't see it right now (I've about 45 ft of ceiling to floor book cases in my office, all full!)

You are supposed to bake the varnish when done, but with today's available epoxy (two part) varnishes you may be able to skip that part. (or just find an old electric range oven and use it for this purpose only!)

The varnish is intended to keep the winding from physically moving, it is not insulation as such. A moving winding turn would 'rub' against its neighbors and eventually rub the wire's insulation off.

Sometimes (if you are lucky) the fault is at the splice where the winding wire (a solid varnish or enamel insulated wire) is connected to the lead wire (a stranded, rubber/cloth or plastic insulated wire). Sometimes these fail.

[bjornb]

Thanks, that reads like an encouragement. :-)
I have access to manuals like the TM 5-6115-275-14 and TM 5-764, but often a "teacher's" quick explanation is the way to go.

[Lloyd H]

The two Voltage sense leads V1 and V4 are common to the output leads so you may have only one ground to find, maybe you will get lucky, certainly worth a good look over. Lloyd H

[cadre]

I know where there is a MEP-018A that might be for sale. It's complete and I even have some pictures of it.

The current owner has never got it running, but he's never tried to get it running. I looked at it for purchase but passed it over.

If you're interested I can get in touch with the owner and see if it's still available. It's located in Blackstone, VA

Bobby,

Pictures of the MEP-018A

[Jim McIntyre]

Couple of things:

Thing 1. I disagree w/ nehog. Rewinding a generator is difficult. If you do it for a living, and have the knowledge and equipment, maybe not so much. But as a total noob? Wow. I rewound one little 400W generator a few years back. It is not easy. IMHO, a MEP-018 is not worth the grief of a rewind.

Maybe I'm an imbecile - Just curious how many other members have actually personally rewound a generator? Was it easy?

Thing 2. Are you sure these sets have shorts? I've worked on a lot of these sets and never seen a shorted stator. Let alone two with the same issue. Certainly it's not impossible, but I'm just questioning your method to determine it was shorted. How did you determine this? (best way I can think of is to disconnect the big 'dog-bone' cable at the generator and measure between the pins) If a visual inspection turned up burned windings, that would be noteworthy.

Did you overload your set before it failed? Did it emit smoke? Do you have a known-good voltage regulator? If so, then probably you do have a short. Otherwise, let's think this over...

[nehog]

Jim, in many ways you are right, it is not trivial, and I may have implied (or said!) it was.

I've done many motors and generators over the years, and I still will say it is not technically difficult as long as you work carefully. It is tedious, and takes a lot of time, however. Not many special tools are needed (an oven to bake the enamel/varnish is good, but epoxy varnishes are possible without baking.)

It is also possible to repair a winding if one wishes to try it. One bad coil doesn't condemn the others, if (big if...) you can get the bad one out, and a new one in without disturbing the existing winding, and that the existing windings are in good condition (not flaking insulation, for example.)

I also agree with your comment about seeing two failed stators. It is very rare to find one, and to have two is even more rare. But, to be fair, it can happen, I've seen stranger things.

[David Bentley]

I have a generator head off an MEP-018 available. Has under 100 hrs on it and was working fine when the nose of the camshaft broke off and trashed the engine. Pm Me... In Lubbock, TX.

[bjornb]

Following some research, my conclusion is that the reason for the generator head failure was an unbalanced load. The unit was set up for 240VAC and using just one leg (120VAC) for an extended period of time running a welding generator, the unit overheated...
Still want to find a replacement head or a complete "parts" mep-018a reasonably close to the western part of Virginia.

[930dreamer]

Originally Posted by bjornb

Following some research, my conclusion is that the reason for the generator head failure was an unbalanced load. The unit was set up for 240VAC and using just one leg (120VAC) for an extended period of time running a welding generator, the unit overheated...
Still want to find a replacement head or a complete "parts" mep-018a reasonably close to the western part of Virginia.

PM sent.

[Jim McIntyre]

Originally Posted by bjornb

Following some research, my conclusion is that the reason for the generator head failure was an unbalanced load. The unit was set up for 240VAC and using just one leg (120VAC) for an extended period of time running a welding generator, the unit overheated...

Unbalanced? sure it was unbalanced, but it takes an overload to burn a winding. Unbalance won't do it. Too much current will. (rocks and pebbles flying around in the generator might cause the problem too )