DIARY ENTRY FOR 24 OCTOBER, 2009
The conversion process required scavenging the magnets from the GE. There is enough room on the rotor of this one to use the same number of mags. That offered the promise that this conversion would produce roughly the same amount of power as the GE, too. Some simple bench tests showed that this was likely to be so.
Some additional notes, after reading comments about my diary entry:
October 25, 2009:
In the process of re-carving I noticed that the root was given an angle that would correspond to a TSR less than 4, while the tips are about 5. That's an oops on my part a few years ago when I made the first set of blades, but they actually work well on these motor conversions I make. There may be a little more "oomph" to get started turning with so much twist.
It's always spinning, even in the lightest breeze. You can feel the cogs when you turn it by hand, and the blades visibly "step-step-step" to start and stop, but that's no inhibition to turning in any wind that would produce power.
The winch is rated for 2000 pounds, and the manufacturer refers to a safety factor of 4, though I think that's a bit optimistic considering its size. It's the biggest worm-gear winch in the Acklands catalog. In my application, I'm putting about 1200 pounds on it just at the start of raising, so my operating safety margin is higher, but not large. No, I'm not completely fooling myself =)
I had to lower the tower to adjust the tail angle, then after Saturday's wind showed me that the tail was too light, I lowered the tower again to put weights on it. So in one weekend I raised the tower three times. The winch performed just fine, but one thing I did notice is how hot the worm gear gets. The grease would get very liquid at these temperatures and I stopped cranking half-way to re-grease. Not sure if that's a sign of doom or perfectly normal. Considering a bigger winch anyway.
October 26, 2009:
A storm front came in at about 10 PM, so I can report that all's well, with about 60kph up there (35mph or so). The tail is just about to furl in these gusts - a little fast but there's little I can do about it now.
I think the stator reactance is already limiting the output below 15 amps. I can't be sure until I look over the PICLOG data tomorrow, but the analog gauge isn't going much higher than 12A.
For the sake of knowing what happens, I hit the "kill" switch. Not a lot happened except it made less noise, indicating that it was running a little slower. This isn't a big surprise, because the stator resistance across phases is 3.5 ohms. Not much of a "short", is it? The GE generator, running in parallel-star had a stator phase resistance of about 1.2 ohm, so there was much more authority at the kill switch because the shorted current was proportionately higher.
Well, unless I resorted to re-winding the stator wires, I couldn't expect much better. This project wouldn't be finished this year if I'd tried doing that. My one remaining theory about motor conversions is the construction of the rotor and trying to re-use these squirrel cage rotors by turning them down on a lathe. Though the magnets stick frimly I'm thinking that the flux circuit isn't the best. Re-making the rotor, with thick cylinders of iron to plunk the magnets onto, is the way to go.
I have little to complain about because this old motor was (like the others) free, the magnets were scavenged from the old crashed genny, and the shop time to re-work the rotor was also free. It's running well in both light and moderate winds, which is where 90% of my wind is anyway.