RE: Synchronous Motor - How to determine . . .

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

Original poster: "Mccauley, Daniel H by way of Terry Fritz <twftesla-at-qwest-dot-net>" <daniel.h.mccauley-at-lmco-dot-com>



I'm just curious, if not an electric flourescent light, what would you
use???

Thanks
Dan



Dan,

The quickest way is to place a piece of white or black tape across
the rotor, and observe the spinning disc under ordinary flourescent
light (not electronic fluorescent).  If the motor is locked in sync 
properly, the faint blurred pattern will not rotate.  You can unplug
the motor and then the pattern will rotate as the motor spins down.
Just before the motor locks into sync as you raise the voltage,
a hunting (unsteady) sound may be heard.  The sound will
suddenly become very steady as the motor locks into sync.
Some folks use a neon bulb and build a circuit to act as a strobe
to see if the disc is synched, but I just use the fluorescent light
method which works well.  Some folks have trouble seeing the
pattern until you gain experience viewing it.  

Sometimes if the motor can't quite lock with the rotor installed,
the use of a larger than normal run capacitor will help it to lock
(assuming the motor uses a run capacitor).  Another way to
assist the lock-up is to power the motor from a 140 volt variac,
or a step-up transformer which outputs 140 volts.

John


>
> I have my synchronous motor with the rotor set-up.  How am I able to tell
if
> my motor is running at the correct speed and that the rotational weight of
> my rotor is not slowing the motor down.  Any easy way to determine this?
I
> don't have access to any type of motor tachometer whether it be a physical
> connect one or ones that use a light beam and a piece of tape on the
shaft.
>
> Thanks
> Dan
>
>
>