On Wed, 07 Dec 2005 21:55:22 GMT, "Karl Townsend"
remove .NOT wrote:

I'm rebuilding a hardinge CHNC...

The machine will be single phase with a VFD for the spindle.

I just found out the coolant pump is three phase. It is 1/10 or 1/20 hp.
Using a clamp type ampmeter it just tickles the needle on the 6 amp full
scale setting. I'll guess .1 to .2 amp per phase.

So, would it work to just use a run cap accross L1 L2 L2=wild legto start
this thing? How large should I try?

If needed, I could use a start delay timer and bring in a cap accross L2 L3.
Need this? How large?

Karl


Don't know if it'similar to your pump but the 1/8 HP
centrifugal suds pump on my Schaublin mill needs 16uF start and
4uf run capacitance. Because of their lower efficiency these very
small 3 phase motors are more difficult to single phase convert
and have dead lousy starting torque. Fortunately this is not much
of a problem with a centrifugal pump unless you're you're using a
high viscosity neat cutting oil.

Because it's a centrifugal pump minimum torque demand is with
the delivery turned OFF. In practice it makes precious little
difference.

Jim