.....Faradays' law states "The voltage induced in the conductor is directly proportional to the rate at which the conductor cuts the magnetic lines of force"....The four factors - strenght of field, speed of conductor with respect to field, angel which conductor cuts field (90 degrees optimum),and lenght of conductor. Are these statements true and are these not the basic principles?
True but: If you work them all comes down to how much flux goes from one side to the other of the conductor (i.e. between inside and outside of a coil times number of turns) in a given amount of time that determines induced voltage.
I haven't heard of Betz, but will google it.
Basic idea is similar to the Laffer Curve with taxes vs. government revenue.
- You get power from slowing down the wind.
- The more you slow down a given mass of air, the more power you get from it.
- But the more you slow down the air going through your mill, the lower the mass of air you can pull power from.
- If you don't slow it at all you get no power because you left it all in the air. If you stop it you get no power because no air goes through the mill - you have to take less than all there is to keep the mill running. In between there's power, and at some point there's a peak in the curve.
Betz is the guy who figured out where the peak is (air leaves at 1/3 the speed it entered) and what percentage of power it represents (16/27, about 59.3%). This is the "Betz Limit".
His simplifying assumptions are very close to the real world case and actual mills can essentially only deviate from them by being not as good (finite number of blades, nonzero air friction, air leaves with some spin that represents more lost energy, etc.). About the only way they can do better than the assumptions is by affecting a little air just outside the "swept area", acting like they were slightly wider than they actually are.
So a "perfectly efficient" mill would turn 59.3% of the wind power into HP on the shaft and real mills fall somewhere below that. "Beating Betz" in a windmill is like beating the Carnot cycle efficiency limit in a heat engine. Don't bother trying. There's more energy there but it can't be captured.
Also wasn't Edison setting up dc stations before ac came along
Yep. The generators used commutators (rotating switches on the shaft) to rectify the genny's AC to DC. Downside: Voltage is limited because they'll arc over if you go too high. So you have to generate near the load (using the technology of that time) to avoid excessive resistive losses in the transmission system. AC had the advantage that it could be stepped 'way up (and back down) with simple transformers, so it could be shipped long distances. (Tesla teamed with Westinghouse to build what engineers had been dreaming about for decades: A system to power New York City with waterpower from Niagra Falls.)
... and that Tesla actually worked for Edison Co. which inspired him to create ac??
Tesla worked for Edison at first. But Edison was heavily invested in DC and wasn't interested in developing and marketing Tesla's ideas. (Foolish: He could have used rotary converters to turn it into lower-voltage DC for his existing distribution system after it arrived.)
