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Forum Index : Windmills : turbine conrtoller via pressure switch
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| carl1 Regular Member  Joined: 16/04/2007 Location: AustraliaPosts: 79 |
Hi to all I am going to control / switch on & off the wind generator via a low pressure switch, easy available: 20 to 300Pa wind pressure = ~ 15 to 40 knots wind speed Should be simple enough to put together for the not so electronic wizard like me. I am shortening the fields on the ac side before the rectifier using power thermistors NTC (AMETHERM SL32 2R025) two in series, 2x2ohm between each field, as well called "inrush current limiters" so the generator doesn't " hit a brick wall" when the fields are shortened. cheers Harald |
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vasi Guru  Joined: 23/03/2007 Location: RomaniaPosts: 1697 |
The pressure switch is like the ones used in washing machines? The sensor is inside a chamber and it have a tube where the air come inside, pressing the switch. I think it needs a large tube to capture more wind because it not have the wash machine chamber for pressure effect .... I think... Also I think you need to have a continuous air flow ... You will use a weather vane for positioning the switch on wind? Maybe you need slip rings for electric wires ... Hobbit name: Togo Toadfoot of Frogmorton Elvish name: Mablung Miriel Beyound Arduino Lang |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5119 |
I used a washing machine pressure switch on a car I turbocharged many years ago. It was a old Datsun 1600 ( 510 ), with a T04 Garret turbo I squeezed in there, feeding into a pair of SU's. I used a distributer from a Datsun 1800, has two sets of points see, 4th and 5th gear would use the 2nd set of points to advance the timing, independent of the vacuum timing. I wanted to retard the spark timing as the turbo boost pressure went up, so I used the washing machine pressure switch fed from the inlet manifold to switch over to the retarded set of point, backing off the timing about 15 degrees. The pressure switch had a adjustment, and I also had to use a heavier spring. This was in the days before car computers and electronic control. I later added a 2nd pressure switch to switch on a water spray into the turbo inlet at full boost. That little car ran over 20 pounds boost and scarred me to death, it was so quick and I could break traction in 3rd gear at 80kmh. Blew a head gasket every 2nd week, and ended up smashing a piston. Ahh, memories 
Anyway, back to the subject at hand. If you can find a vacuum switch, that would be easier to use in this application. Use a upside down plastic or steel bowl with a tube from its middle, will act as a venturi and create a vacuum in the wind. Its not directional, so doesn't need to track the wind. 
Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| carl1 Regular Member Joined: 16/04/2007 Location: AustraliaPosts: 79 |
Hi Vasi & Glenn I have tested a dozent different washing machine switches at their lowest setting. They will switch at speeds of 85 to 90km/hour, too high. I found low differential pressure switches used in air flow controll which will switch from: 0.2mbar = 20Pa = 2cm watercolum =~7m/s windspeed=15Knots. up to 300Pa+ = 20m/s windspeed/pressure = 40knots - perfect range. They will work as well with vakuum / suction, so with Glenn's omnidirectional sensor it's all set? I will do a test run with a bowl, maybe two bowls opposite, I think it should not matter it the bowl is up or down? ( up then no rainwater could go in). Harald |
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| grub Senior Member  Joined: 27/11/2007 Location: AustraliaPosts: 169 |
Try the pressure switch out of a dishwasher, they use less water height and should activate with less pressure. |
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| carl1 Regular Member Joined: 16/04/2007 Location: AustraliaPosts: 79 |
Hi grub I have tried some of them as well, a dishwasher uses a float switch for this level of water. Harald |
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| grub Senior Member Joined: 27/11/2007 Location: AustraliaPosts: 169 |
Most of the dishwashers I see use a pressure switch for water level and a float switch to sense flooding. Vulcan (Dishlex), Simpson and similar use a pressure switch usually found behind the lower front panel. Also the pressure switches on most common washing machines can be adjusted by the screw on it's back. Then there is the car vacuum advance setup you could consider too. Whatever you use, I hope you are successful. |
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| carl1 Regular Member Joined: 16/04/2007 Location: AustraliaPosts: 79 |
I did some test runs today with the differential pressure switch connected to an old float ( sphere, thank's to Glenn ) ) diameter 150mm with a hole on top 3.0mm. I was holding it out from a driving car, so test results are not to accurate , not important because its ajustable anyway. I just wanted to know what range I get out of it: This pressure switch has a range of 20 to 300Pa. at 20Pa it was switching @ 25km/h = 7m/s at 100Pa @ 40km/h = 11m/s at 150Pa @ 60km/h = 16m/s at 300PA - didn't bother to test, anyway beyond the range required. Harald I have to new switch over, they are nearly 100 Euros new, A$60 incl. shipping each. BTW: works upside down as well 
and some info for "grub" : I tried a dozent water level switches from different washing machines and dishwashers , adjusted them to their lowest level: the ealiest I got them switching was at a speed of 85km/h = 23m/s , that's much to high. - H. |
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