Monday, February 2, 2009

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WIND MILL

This is a sail type slow speed Wind Turbine . I have selected this type after studying various types of blades. I did not select the 3 blade airfoil type as that works only at high wind speeds . Where as the sail type is majestic in movement and works even at low wind speeds.The design of the blades is very simple with 4mm wire frame .The design of the blades is very simple with 4mm wire frame . Each frame is covered with a plastic cloth which was replaced now with a0.5mm aluminum sheet using pop-up rivets. Each sail assembly swivels around a 12 mm steel pipe with springs at top and bottom to yield when the wind speed exceeds the limit. This acts as a speed governor. The assembly rotates at 40 rpm and with two set of steps the speed is increased to 400 rpm and a derated permanent magnet DC generator which generates about 150 Watts. This charges the 12V 120Amps Battery. A solar electric panel is also connected to the same Battery. This battery used to light the 200 LED path lights made out of bamboo and coconut shell. The Lights deteriorated within one year due to men and animal interference and the attack of white ants.

The Assembly rotates on a brass lined sleeve, I have used a 25ft surplus Electric Pole with a addition of 6ft steel structure at the bottom which is welded to the base plate with a hinge and fixing bolts. For installation we use pulley block with a prop pole . We have used 4 Anchors with adjustable U-bolts. The Unit has survived two mishaps one with the entire assembly coming down due to bad concreting of the anchor and 2nd time with the unscrewing of the 4 flange nuts, fortunately the blade unit was hanging from the shaft and had not come down.



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