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 to 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
Try 3 to 5 MFD and make sure it is not staring under load, once it spins up to speed close the coolant valve . Be carefull not to allow too much back pressure so that it slows the pump down. You will need to leave the capacitor online.
"Karl Townsend" wrote in message news:eTIlf.410$ snipped-for-privacy@newsread3.news.pas.earthlink.net...
Thanks for the tip.
Don't outbid me.
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
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