Big Generator

Well, i grabbed these two generators on sale, just one will push the arc welder to work on 3/16 plate, but it's a lil anemic and wouldn't power anything else while welding (like the microwave oven, boat electronics, battery charging), but two will operate it just fine. Oh, i hear someone saying "circulating currents!", but wait! These are wired as multiple 120v windings, so if i put all of them in each generator in parallel, then put the two generators in series, i get my 60a@240v, and no circulating currents!

Then, i rotate the frame of one generator 90 degrees from being sync'd to the other one, and that gives me 2phase power. If i rotate it 60 degrees, then swap the power leads 180 degrees, i get phase3 of a traditional 3phase system. The phase2 line can be made from the phase1 and phase3 line. Alternatively (no pun intended) i have the 75a@208v 3ph generator i got 10 years ago which i can't use because of the neighbor... but 1) that's too much electricity for one small boat, and 2) 208vac isn't 240vac.

These generators won't be running full time, possibly not even once a week. I plan on a much smaller 10a@120v to supply most power, and even it won't be run but 30 minutes a day at most (think microwave oven), if that. I have ten 15watt pv solar panels i will be using to give me some power straight to batteries, and i wish to look into concentrating thermal solar, wind, and OTEC power.

Anyhow, this page isn't finished, but neither is the generator, so here's some pics in progress:

Piece fitting:

Here's the generator mounted on the idler rails, being manually turned, with the rotor shaft in a solid coupling to the drive shaft. There is no binding when spinning either the stator or the rotor in any combination. There will be zero radial loading on the flex coupling.

A really bright pic so you can see what's there, because the rest are dark.

Now the pics forming a series thru a clockwise rotation:

Jumping ahead, in case you don't want to wade thru the how-to, here's a trial fitting of all shaft, it's bearings, the pulleys, and the rubber couplings. These couplings are stiff enough, yet have enough give that they tolerate some misalignment. The blue pillow block bearings are on the underside of the H bridges because the iron housings last longest when under compression, not tension, and since the engine will be above, pulling above, i put the bearings where they'll last longest.

You may have thought, looking at the first pic on this page, that putting the rotation disks on the one generator made the assembly take up a lot more room. In this pic below, you can see the disk-less generator is sitting up on a steel channel to align with the disked generator, and the channel is only raising it 1.5 inches. That's not excessive, and considering i want unrestricted airflow all around the generators, once totally enclosed, i have 3 inches clearance between the generators themselves and the enclosure walls, which i'd have even if i used no disks.

Attaching rotation disks. These disks were rough cut out of 1/2 inch thick steel plate by my favorite steel supplier, Besco, in Birmingham. I cleaned them up, welded flanges to them, fit them to the generator, trued them with the grinder.

Attached:

Building a body grinder holder. I want the grinder held tangent to the rotation disks, and it's more simple to make the holder tangent than to make a holder and try to hold the grinder in it at tangent.

Using the grinder holder to round the disks and remove all torch grooves. Why not use a lathe?, because i didn't have one, this assy weighs 200lbs, is 2ft long, and 14 inches in diameter. Even if i had a lathe which would hold this, i likely could not have moved this to the lathe and back again without breaking something. See the visegrips to the left? Those are holding the input shaft of the generator, and another set are holding the other end of the shaft in the generator end bell, so i am rotating the generator housing and the rotation disks, on the stationary shaft, making the outer edge of the rotation disks true to the shaft.

Watch out for disk clogging. Enough of that and it stops removing material, and the motor tends to burn up the more you push it:

Here it is, rounded, rough from grinding on the abrasive disk's outer edge.

Flat, on tangent, to smooth the waves in the plate's OD caused by grinding fast on the OD of the disks.

Here is where you really must watch for disk clogging, i went thru 5 disks doing this.

I think it's neat how the grinder snuggles into the 3 inch channel.

And here it is all finished, after some power sanding with 40 grit.

It's a generator thing, it's going to rust, etc, i am not going to spend time with 160 grit!

Here's the two idlers that keep the generator from going left-right and off the idlers that hold it up. Naturally, all those nuts will be replaced with nylocks before it's run.

A view up under the generator:

I just thought i'd mention, the welds on the back of the rotator plates aren't the only welds there are, they are just the only welds you've seen until these two closeups. I did not weld all the way across for several reasons, mostly no stress from the generator in the middle, and i didn't want to risk warping anything. Anyhow, i did a short hot quick pass, then ground it down some so the generator aluminum wasn't sitting on weld bead.

Here's how i use a grade 8 bolt, the only way to align stuff while also holding it together. The unthreaded shoulder of the bolt passes completely thru both pieces of material, here the steel angle and the aluminum generator. Also, the bolt hole is nearly a press fit, i tap the bolts home with a hammer. You may also note the different sized washers. There's a reason, see the following text and photo.

Note the off-center ring imbossed into the washer in the pic below, to the left of the center hole? That's where the nut contacted the washer. The washer is the "correct" one specified for the bolt, however, you can see that only 1/2 the bearing surface of the nut was actually on the washer! So the load on the nut and the bolt was also offset. So i tend to buy "undersized" washers that actually fit the bolts.

Aluminum can cold flow, and so in the above photo i put a "proper" sized washer nearer the aluminum so there's less stress right up against the bolt, seeing as how it's already a press fit. And as i needed two washers there anyhoo, it just made sense to use the appropriate ones for the tasks. I've been known to drill washers to suit me.

This is what you get if you torque a grade 8 bolt thru a lesser grade nut. The bolt can rip the threads right out of the nut.

 

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