Re: High speed induction motor update

On Sat, 18 Aug 2007 10:15:27 GMT, "colin"
<colin.rowe1@xxxxxxxxxxxxxxxxxx> wrote:

Hi,

If anyone remembers I was messing about trying to modify a 2 pole 240vac
induction motor to go at higher speed and lower voltage driven from a d***
based 3ph pwm setup.

well I got some of that magnetic paper wich goes black in the presence of a
magnetic field,
I put a circle of it in the center of the stator but was very little to see,
it apears the paper only goes black if the megnetic field goes
perpendicularly through the paper,
wich it doesnt with it aranged this way.

but anyway I had a realy extra strong cup of coffee and traced how id
conected the 4 windings to the 3phase
(there were 16 slots wich made it awkward)
and realised id got one phase backwards.

changing that it now runs at a whoping 20krpm.
it realy starts to sing,
and its not realy balanced well enough as it only made for 1500rpm.

it was only an experiment,
I only put a few turns of wire loosly through the slots,
I also need to bore the rotor out so it can sit in the middle of a 1M long
12mm dia shaft.
I think I might need to trim the cooling vanes on the rotor too.
however I realy need a motor 2"x2" this one is a bit to big to fit in easily
at 70x70,
its from an old 8" floppy drive to drive the main spindle.
ive been looking around at all sorts of junk,
but nothing just the right size yet.

my usual stockists only seem to have larger motors.

Colin =^.^=


Modern chem lab centrifuges and turbomolecular vacuum pumps use
magnetic suspension bearings and ac drive. They measure rotational
speeds in kilohertz.

John

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