Friday, August 21, 2009

The Alternator and Hub

I have been writing about the epileptic power distribution and generation in Nigeria and how I built my home made wind turbine to supply 3500watts (>2 horse power) to my home in Abuja. I stumbled on a note on the internet about a government project ( in Katsina aimed at harnessing wind energy for local communities. Nice to know that Government has caught on – I have also noticed uncountable solar street lights in various Nigerian towns and wish them luck on their project. We have seen how to make the blades, so I will go to the motor:-
The Alternator
I spent days on end at Deide (a suburb of Abuja) Pantaka looking for PMC Alternators that were light enough to haul up in the air, and most importantly drive at least 12 volts on a low RPM. Due the poor electric power generation in the country, there were large alternators to be found everywhere, these would serve well for a large wind turbines but not the tiny one I plan to build. I checked on ebay for turbine generators, but considered my rules, I decided against importing a wind generator on eBay. I eventually found a 2.5 Horse Power 230 Volts, 4000 RPM motor that looked like it seen better days. After cleaning it up, and changing the carbon brushes, it was good enough to use.

Unfortunately, they couldn’t find a hub to fit the motor when I bought it, so that meant I had to machine a new hub to fight the motor and also hold the wings.

My old friends from university all came to visit me over a “private matter”, while we were drinking out, I happened upon a broken down machinery and lo and behold, in it sat a light weight Treadmill motor. Though the motor was not rated, it compared better than the 90 volts one I bought earlier. Luckily this time, there was a fly wheel with a pulley for a 6 track belt drive. Just what I have been looking for.

Picture of the new motor
The Hub
I had initially fabricated a pulley for the first motor, but it rattled and vibrated dangerously when I fitted the blades and ran the motor with the aid of an electric fan. You can clearly see the wrong holes are not aligned- the lines show where they should have oriented from

The vibration was due to miscalculated angles for the blades. The three blades were meant to be at a 120 degree intervals, but my over enthusiastic “Turners” drilled the hole by sight. I guess nobody taught them the rule – measure twice and cut once! From now on, I must be present while all my job is done.

They now all weigh a little over 7kg each. I also noticed that the blades weighted significantly different from each other. So i had to plane-off each blade to bring them all to the same weight. They now all weigh a little over 7kg each.

Cheap fix, weld in the wrong holes and re-bore new ones in the right place At first I didn’t want to start from scratch, so I tried to fill and drill the six holes at the right angle again. But after buying the second motor with a flywheel, I went ahead to drill the new hub.

Show picture of the new hub with holes

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