SRSG Synchronicity Test

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Original poster: "Ian McLean" <ianmm-at-optusnet-dot-com.au> 

Hi all,

Thanks for the tips on checking my motors sychronicity after grinding the
flats.

BTW, the grinding went fine, although I might need to shave a little more
off one of the four flats to make it even and balance the motor up a little.

I attached a square of white styrene sheet with a thick black cross drawn on
it to the motor spindle with a rubber grommet.  I put it under a flouro
light.  Apon applying the 240VAC, I couldn't really tell, guess my eyes
weren't trained for it, so I hooked the motor up to my variac.

Starting at 0V, motor starts spinning at about 50VAC, the sound of the motor
is noticeabley different, and you see the light and dark fan shaped shadows
moving around in a circle.  The variac hums.  The motor sounds like it is
'hunting'.  Between 50 and 80VAC, the motor tries to synch, but slips.  This
also makes a unique sound, and you can see the shadows going stationary, but
then slip and move around again, then go stationary, etc. etc.  At 80V and
above, the shadows remain rock-solid stationary (I can see them now !!), and
do not move anymore.  The motor moves smoothly.  The motor does sound
different as I up the juice from 80VAC to 240VAC, but I guess this is just
the sound of increased power and torque.  The speed seems to remain
constant.

If I slowly move the variac back down, the motor loses synch at about 50VAC,
and below 50VAC, my variac starts humming in a nasty way, and the motor
sounds noticeably different and starts hunting again.

I cannot grip and slow the spindle of this 600W motor, before or after
modification, so am not sure yet wether it will hold synch under load, or
whether I might need to grind the flats a little deeper.  Seeing as I cannot
grip and slow it at all though, I think it will be OK.

I guess it worked :) :) :)

Thanks all,
Ian