RE: Salient Pole Modification

["David Dean" <deano-at-xxxxxxxxxxxx> (by way of Terry Fritz <twftesla-at-xxxxxxxxxx>)]

Hi Herbert,

750W/HP so 450/750 = 0.6 HP
Also rule of thumb for PSC type motors is approx. 20uF/HP so 16uf would put
it at
about 3/4 horse max.

As far as cutting the flats, the best method I have found is to install the
disk
on the unmodified motor (preferably with the electrodes mounted to the disk
exactly
as it will be used) and run it to get an amp draw. Then take the motor apart
and
mill some flats, but not a lot. Put it all back together, and take another
amp draw.
Keep repeating this procedure until the amp draw is 85 to 95 % rated FLA at
rated voltage.
This will give the best compromise between torque and lock up at low voltage
without
over amping the windings. Yes it is a lot of work to take the motor apart
and put it
back together several times, but one motor I did that way locks at about
130V and gives
almost 40 degrees of adjustment over a 130 volt change. (Min voltage for
lock 130, max
available 260, nominal input 240). I set the physical position of the motor
for best
results at 160V in, then I can advance or retard 20 degrees wile running by
adjusting
a small variac that feeds the motor.

later
deano

> -----Original Message-----
> From: Tesla list [mailto:tesla-at-pupman-dot-com]
> Sent: Thursday, November 09, 2000 7:54 PM
> To: tesla-at-pupman-dot-com
> Subject: Salient Pole Modification
>
>
> Original poster: "Herbert Mehlhose" <herbert.mehlhose-at-kdt.de>
>
> Hi everybody,
> I just received the motor for the SRSG I'm planning for my new coil.
> The motor is rated as follows: 230V, 3A, cos phi 0,87, 0,45kW, 2870/min,
> 50/60Hz.
> A capacitor of 16uF is already mounted.
> I ordered this motor (Made by Bauknecht, they build washing machines,
> so I assume, this motor was intended for that use), as it seems to be
> ideal
> for a 3000/min SRSG (50 Hz in Germany).
> My rotary disk will be G10 with aluminium ring, diameter 18cm (about 7
> inches),
> that's quite small, so the power of the motor should be ok, even with
> calculated
> losses due to the flats I will make in the armature. To run at 3000/min,
> this motor
> should get 2 flats.
> My problem is, that I cannot identify any starting windings with thinner
> wire
> and also no dead stator poles, i.e. poles without any run windings
> around them as
> described in syncmot.zip.
> How can I determine how many poles the flats in the armature should
> span?
> The stator has 24 poles all in all.
> I think I remember an append of John Freau, wo said, that for a 2 flat
> motor, the
> flats should span a maximum of about half the diameter of the
> armature??? Can
> anybody confirm or give some more exact value, please.
> As to the HP: this means horse power, I assume. In Germany we call this
> PS
> (Pferdestaerke), a measuements for the power of cars. Now the official
> measurement
> ist kW. If 1 HP is equal to 1 PS, my motor would have about 0,6 HP.
> I'm almost sure, that my assumption HP = PS is correct, but can anybody
> confirm that?
> Thanks very much for any advice,
> Herbert
>
>
>