On Sun, Mar 05, 2017 at 07:13:22PM -0500, Gene Heskett wrote: > On Sunday 05 March 2017 17:16:36 John Hasler wrote: > > > Gene Heskett writes: > > > Very simple. With the glaring exception of the modern AC induction > > > motor that in 99% of the stuff we buy, ANY other generator can also > > > be used as a motor... > > > > Induction motors can function as generators. You just need to connect > > them to an appropriate AC source and drive them above synchronous > > speed. > > > Yes, there is that exception, they need an excitation current, true, but > in that case they make excellent brakes as they don't like spinning > above synchronous any better than they like running below it. And with > enough dc current you can come pretty close to stopping them dead in > their tracks. Certainly within one revolution. But the armature is > soft, and its not possible to maintain the magnetic field from its > shorted turns armature long enough to extract any output power from it > for more than a few milliseconds.
In other words Back EMF? I know a chap who found about that the hard way when he tried to get something from nothing by charging a battery from a generator which he turned by having a fan connected to it. :) He didn't get electrocuted or anything, the fan abruptly stops turning. -- The media's the most powerful entity on earth. They have the power to make the innocent guilty and to make the guilty innocent, and that's power. -- Malcolm X
