a faster motor

[[email protected]]

|> I would like to find a small inverter (or circuit to build one) which can
|> put out a small amount of THREE-phase AC. The idea is that it would be a
|> good and safe source of power for small experimental tests of how things
|> work that need three phase power to work. It could be used to demonstrate
|> small three phase motors. 24 volts or less. Adjustable frequency would
|> be cool.
|>
|> --
|> |---------------------------------------/----------------------------------|
|> | Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below
|> |
|> | first name lower case at ipal.net / [email protected]
|> |
|> |------------------------------------/-------------------------------------|
|
| If you have a 3 phase supply, then arrange 3 good coils in an equilateral
| triangle. Put a shaft in the middle and, on this shaft hang an aluminum film
| can (if available these days). Failing this, put a beer can on the shaft so
| it is free to rotate. Energise the coils. Try it with a paper clip hung so
| it can rotate. Reverse one coil and see what happens. Once started see if
| it will keep running if one coil is turned so it doesn't contribute to flux
| at the center.
| Once you have finished with the induction motor, try going synchronous. Use
| a very small and light compass needle (the kind I used was one of the little
| half inch diameter toy compasses.
| I have done this- mind you the coils were originally field coils from a 5HP
| shunt DC motor and the AC supply was at 220V, 60Hz. The coils did get hot
| but the motors did work.

Or another option would be to build a permanent magnet type three phase
syncronous motor/generator and attach a hand crank.

 

[Don Kelly]

|> I would like to find a small inverter (or circuit to build one) which
can
|> put out a small amount of THREE-phase AC. The idea is that it would be
a
|> good and safe source of power for small experimental tests of how
things
|> work that need three phase power to work. It could be used to
demonstrate
|> small three phase motors. 24 volts or less. Adjustable frequency
would
|> be cool.
|>
|> --
|>
|---------------------------------------/----------------------------------|
|> | Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address
below
|> |
|> | first name lower case at ipal.net /
[email protected]
|> |
|>
|------------------------------------/-------------------------------------|
|
| If you have a 3 phase supply, then arrange 3 good coils in an
equilateral
| triangle. Put a shaft in the middle and, on this shaft hang an aluminum
film
| can (if available these days). Failing this, put a beer can on the shaft
so
| it is free to rotate. Energise the coils. Try it with a paper clip hung
so
| it can rotate. Reverse one coil and see what happens. Once started see
if
| it will keep running if one coil is turned so it doesn't contribute to
flux
| at the center.
| Once you have finished with the induction motor, try going synchronous.
Use
| a very small and light compass needle (the kind I used was one of the
little
| half inch diameter toy compasses.
| I have done this- mind you the coils were originally field coils from a
5HP
| shunt DC motor and the AC supply was at 220V, 60Hz. The coils did get
hot
| but the motors did work.

Or another option would be to build a permanent magnet type three phase
syncronous motor/generator and attach a hand crank.

You can put a crank arm with two (can use 1 but two is better balanced)
magnets in front of a copper disk which is co-axial and free to rotate. Turn
the crank- lo-induction motor. Replace the disc by a second arm of the same
radis with magnets and get a synchronous hand cranked motor- provided that
you don't try to accelerate or put much load on it.
Lots of simple devices work well.