🚀 go-pugleaf

> grossman@bbn.com (Martin Grossman) writes: /  8:17 am  May  3, 1989 /
>
>I need to get a sync motor running and need help
>
>The motor face place reads:
>
>	synchronous
>	voltage 120
>	frequency 60Hz
>	1 phase
>	torque 90inch ounces
>	capacitor .85mfd
>
>
>	it has 3 leads.
>
>	I measured the resitance on the leads as follows:
>
>    black           blue           red
>      o              o              o
>      |              |              |
>      --- 750 ohms -- -- 750 ohms ---
>      |                             |
>      ------------1500 ohms----------
>
>
>Question:
>	which leads do I hookup the 120V ?
>	which leads do I hookup the capacitor ?
Blue to one side of 120VAC line.  Other side of line to both the
red lead and one side of the capacitor.  Other side of cap to black.
That is, black in series with capacitor, to red; red and blue
to line.  If it runs backwards from what you want, put the
cap in series with the red instead of with the black, so black goes
directly to the line and red is thru the cap.  Note that this is
simply connecting the cap between black and red, and connecting line
to either black or red (other side to blue).
>	what type of capacitor (.85mfd) do I use ?
If you can possibly find one, it should be rated for AC motor run
service; I don't recall what's standard, but I think something like
"150 VAC".  Usually the exact value isn't toooo critical, and 1.0 uF
would likely be OK, but try some place like Grainger -- they very well
may have such a beast.  You can use a plastic film DC-rated cap, too,
but you may have trouble with failures due to the fairly high AC current
in the cap.  I wouldn't expect the failures to be spectacular, so feel
free to try if it comes down to that.  Should be rated at at _LEAST_
200 VDC.  I'd look for one with low series inductance, simply because
that probably also means low effective series resistance.
>	what should the voltage rating of the capacitor be ?
(see above)
I'd also fuse the circuit.  I'd try a 2/10 amp fuse, or better, 
measure operating current and use about 2* that.
>
>PS
>1) This is a motor used for a telescope clock drive.
>2) The motor has a built in gearing so shaft rotates 2RPM
>
>respond via email to:
>	grossman@bbn.com
>		or
>	uunet!bbn!grossman
>----------
Sorry, neither of those addresses worked for me .. I tried.