Re: Phase controller question.

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Christoph Bohr" <cb-at-luebke-lands.de> 

Hello John, All.

 > I don't understand why the motor would change from a 220V motor
 > to a 90 volt motor after modification.
Me, too. But I had it running one time when received it from an ebay seller
and it sounded completely normal and quiet at 220V.
'though this already proves it was a 220V unit I double checked the
nameplate and wiring instructions and there is not even a way to wire it for
110V,
the only plausible alternative in europe, thers is only wiring to be made
for clockwise / counterclockwise operation.

 >  I understand that the motor may lock into sync at 90 volts, but generally
the full supply voltage
 > is supplied to the motor anyway.
This was, what I experienced with the other motors ( only 2 ) I modified for
other RSG's before. They sounded normal at 220V but got a little warmer than
prior to grinding flats.

 >  Did you rewind the motor
 > windings or something?

No. Only new paint and new bearings. rewinding a motor woulb be a bit too
advanced for me ;-)

 >  If you supply only the minimum voltage
 > that can lock the motor into sync, then it may lose sync under load
 > when the rotor is attached.  Or perhaps you have the rotor attached
 > already?

I have the complete rotor disk attached. When I have it running at 90V under
fluorescent light I can see how it syncs. When I take a cotton cloth and
press it against the spinning disk, I can see how the angle of the attached
pattern slowly moves  ca 30 degree away and then the motor looses sync (
This can be heard and seen clearly ). It really takes pretty much force (
additioinal loading ) to get the motor out of sync. Strange....

 >  Generally if the motor is run at such a low voltage, it
 > may have trouble remaining sync'ed over the full variac phase
 > controller range.

I still had no chance to veryfy this, but at least it does not sound as if
it was loosing sync. But I will ckeck this when I have my fluorescent lamp
back.

 >  Maybe the system is only giving a
 > limited phase adjustment range because you're feeding the motor
 > such a low voltage?

This of course might be true. In this case it seems like I will have to set
the phase manually....., anyway, this worked before there were phase
controllers.

 >  I would use 220 volts for the motor and not
 > use the stepdown transformer unless something unusual is going
 > on that I don't know about in your system.

The sound and rapidly rising current draw of the motor force me to stay at
90V. Even at 110V the sound becomes somewhat awesome...

The good news is: I made a blown static RQ-gap yesterday from scrap parts
and made a first run with it today. Together with the finally fixed
MOT-Stack
I at least was able to achieve 4,5 feet streamers at ca 2,5KVA ( non PFC )
and performance was fery smooth. I never thought a static gap could perform
this good
in a maggie. The gap setting was still pretty narrow and resulted in
something that sounded at bit higher than 200BPS. So I think it is not
unrealistic to expect 6feet when the RSG finally runs properly ant the
MOT-stack has its 6th MOT back.

Thanks for your feedback

best regards

Christoph Bohr