Twas the night after christmas, and all 'round the house, not a creature was stirring, except the turbine,
which had picked up an awful growling sound. Can't be good, so I shut it down for the night to check on
it in the morning. It was windy in the AM, but instead of starting up promptly when I released the shut-down
switch, the blades merely crept around and started making that nasty noise again. Not good.
From the ground I tried a few tests, which made a short-circuit between wires seem likely. I disconnected
the wires at the base of the tower, and most showed continuity, picking up the resistance in the generator's
windings. Then I found one pair with virtually no resistance at all. A short-circuit? Where? Anywhere in the
tower from top to bottom. The tower would have to come down. I haven't tipped the tower down since
the fall of 2010. The winch and all the necessary tools were still in place, and I had the sense, last time, to
write notes about doing it properly. The only snag was noticing that the winch needed grease when the
tower was half-way down, but the grease-gun was still in the garage. Something to add to my notes.
Once the tower was down, I set about looking for the fault. I disconnected the generator, and checked all
of its wires for continuity through each phase, and shorts across phases. All Okay (whew!). Then I checked
the tower wires. In the photo below the meter is seeing no resistance ("0.000") in two wires that are
supposed to be separate. The problem is definitely a short between these wires in the tower.
Come to think of it, I remember a day, not long ago, when the wind shifted from west, to north, then east,
then completed a full 360 degree turn by the next morning. Opening the top of the wire conduit, I can easily
see how twisted the wires are now. There must be half a dozen twists in the wire. Since this could be the
cause of the problem, I swivel the whole thing around and around about 4 or 5 times until these wires come
back straight. Short-circuit disappears. I think I am at the bottom of the mystery, but it means that there is
damage to the wire insulation, somewhere inside the tower head. It has to come apart now, too.
When I got the tower's head apart, I saw the source of the trouble. These two wires were scraped during
all the twisting, scraped in the same place, and then further twisting brought the two bare wires together.
I replaced these wires, by splicing in new lengths of wire. I finished this just as the sun sets. During these
short winter days (9AM to 4PM) there isn't much time to get a lot of work done. What work I can do is
hindered by the stiffness of these cold wires. The wind came up in the afternoon, carrying dark clouds with
it. I came back into the house chilled to the bone.
The next day it's even colder, and a hoar-frost has settled on everything. I get out a hair-dryer to remove
the ice crystals before re-assembling the wires and terminals (water must not contaminate any electrical joint,
even when it's frozen). While the tower is down, I have this opportunity to examine everything, including
looking in the generator to see the state of the magnets inside (excellent) and the condition of the blades
(minor wear). The tail hinge was fine too (last year I found a fatigue crack in it). Finally satisfied that it could
go back up in the air, lifting the tower took just a few minutes to prepare, a few minutes to carry through,
and a few more minutes to tidy up afterward. I always seem to bring out every tool I own, and a spare, while
doing jobs like these!
There wasn't enough wind to start it yesterday when I raised it, but it finally re-started in the wind this morning.
Nice and quiet. Ahhh.
