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If you think I'm stupid and lowly educated, why SIEMENS hired me then Punks? - Page 15

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Posted by Ulysses on August 5, 2009, 2:27 pm


overload -




order to


Is this something that was known or theorized before they were first built,
or was it discovered the hard way?

So, would a typical 3-phase alternator which has the rotating field coils
fed directly by brushes and slip rings be called a synchronous generator?

Posted by harry on August 5, 2009, 8:47 pm

It could indeed. It could be no other!
BTW, You should not think of "motors" and "generators".   They are the
same thing.
Think of AC machines and DC machines.

Posted by clare on July 31, 2009, 2:35 am
 On Thu, 30 Jul 2009 10:54:09 -0700 (PDT), harry

I know the theory of induction motors.I've run induction generator (3
phase with caps to make single phase power)
 I also know the theory of dc, wound feild and PM motors, and the
difference between a DC an a universal motor - and the
advantages/disadvantages of series, shunt, and PM DC motors.

Also how to apply that theory. I've built and driven my own electric
car too - and not from a kit.

Posted by daestrom on July 31, 2009, 1:53 pm
 harry wrote:

Your post is describing the starting mechanisms of induction *motors*.
We've been talking about induction generators.  While they are
constructed the same, they are not operated the same.  You don't need a
starting capacitor for a generator, the starting is done by the prime mover.

Induction *generators* need magnetizing current supplied to the stator
in order to create a magnetic field for the rotor to spin in.  This is
either supplied by the grid or external power source if you connect it
to another supply, or by the reactive power of an external capacitor
bank.  Without it, the magnetic field and output voltage quickly
collapse you end up with nothing.


Posted by clare on July 30, 2009, 3:17 am
 On Wed, 29 Jul 2009 10:29:14 -0700 (PDT), harry

 The capacitors supply the feild current (off phase) to make it work.
I am unaware of any way to make an ofline induction motor generate
without capacitors installed. If there is a documented way to do this,
please provide the link.

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