My son and I just landed our keeper lathe, a Cincinnati 13x48 Hydrashift with a 3HP motor. I have a VFD but don't want to use it with this lathe as it needs to be connected directly to the motor, so I want to build 5-10HP RPC. I have been reading and studying for days, to me it looks like the Fitch 1998 design would be best for my needs. I have everything except the damn motor, going out this week to find one, everything else is laid out on the tailgate. I don't currently have any other 3 phase requirements, but who knows, maybe a milling machine will find it's way into our shop one day.
So is this still the "go to" design? Cost is no object as I have pretty much everything except the motor.
Thanks!
I probably had enough relays and capacitors in the Hell box to build six to ten RPC's. Among other quirks, I hoard Mercury-Displacement contactors and Crydom SSR's.
As with rather a lot of PM'ers, "other demands" on time, etc. so I just
bought mine from Jim Gorman, "Phase Craft". He has retired now, no longer builds them. I didn't even bother to see which "design tribe" he based his units on. They JFW.
Jim's the guy to ask, if he dasn't mind the bother vs fishing or wotever.
That said, when one selected a Phase Craft, the selection criteria included pole-count, eg: idler motor "base" RPM. He optimized for that characteristic as well as for HP. That may be a part of WHY his units "JFW".
Ergo I bought my idler motor (a brand-new Weg, Brasil, 10 HP Open Drip Proof case style)
FIRST. ISTR it was about $384, shipping included.
I just yesterday ordered a 27 KVA Delta-in, Wye-out transformer for it. It will be gaining a 5 HP supplementary idler, arranged so I have a 5 HP, 10 HP, or 15 HP idler "array" line side of the one transformer. My max starting load is a 7 HP, unloaded spindle, but no clutch. Two like that, actually. My max running load is likely to be 3 HP., average running load mebbe 1 to 2 HP.
Find the idler motor
first.
Give a thought to the "supplementary" idler concept. You may be able to reduce the need of diddling balance caps, still have the stones for starting and/or running heavy loads.. or operating lighter ones with less idler noise and fewer wasted ergs.
The Delta-Wye transformer is simply because I DETEST corner-grounded or high-leg Delta existing "outside of its box".
2CW