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Re: sync motor RPM ???
---------- Forwarded message ----------
Date: Wed, 22 Oct 1997 07:18:02 -0400 (EDT)
From: FutureT-at-aol-dot-com
To: tesla-at-pupman-dot-com
Subject: Re: sync motor RPM ???
In a message dated 97-10-21 00:13:42 EDT, you write:
<< ssnip> I checked it to see if it
> was running 1800 RPM's but I don't think it is. Fluorscient lights should
> blink at 60 HZ and make the shaft appear to be stopped but it doesn't. I
> connected a neon light in parallel with the motor and use the light in the
> dark to see if the shaft appeared to be stopped but it isn't. I put a
diode
> on the neon so it would blink at 60 Hz and tried again and the shaft still
> does not appear to be stopped. The shaft keyway can not be seen even if I
> move the neon light all the way around the shaft 360 degrees in the dark.
>Any ideas?
>Gary Weaver >>
Gary,
It's hard to tell if the motor is locked by observing the shaft.
Try making a round cardboard (actually any material) disc
about 5" in diameter and colored white. Attach the disc to
the motor shaft, and use a black magic marker to draw a 1/4"
wide straight line across the diameter of the disc, so that the
line passes through the center. Now when you start up the
motor, and observe under fluorescent lighting, you should see
TWO black steady lines on the disc, which will be at right
angles to each other and will form 4 quadrants.
To make it easier to see, turn down the variac so the motor loses
lock, then turn is up again, etc. and you'll be able to see when the
lines become fixed in position by strobe effects. The black lines
will not be clear, but will appear smeared greatly, thus making
it a little difficult to see. Also, at a certain (low) variac setting, the
motor will make a hunting sound as if it is trying to lock, then if
you turn up the voltage a little more the hunting sound will slow,
and then disappear, and a steady sound will emanate from the
motor indicating that it is locked.
Hope this helps, synching for today and tomorrow,
John Freau