Awl--
So I been agonizing over this, reading Fitch's stuff, bunch of other stuff, and everyone seems to have trouble balancing the lines.
So I'm about to bite the bullet, and shell out some hefty bucks for converters that supposedly hold +/- 5% between any leg--which is still not great--but I cain't quite get the straight story from the various commercial sources. Some suggest they somehow load/unload caps with load, which others say is not so great for pyooters/cnc, etc.
Phaseperfect.com has very pricey digital converters, 1% regulation--not rotary, not static, just pure 120 deg 3 ph, they say. With really good amps. But, cnc mfrs I talked to hem and haw about the digitals, but the specs are sure nice. Heavy, but not quite as heavy as rotaries.
But the gents at
Forget caps and all the bullshit, the guy said, just get the biggest assed idler you can!!! THIS is what stabilizes voltage!
So, I happen to already have an rpc "bank": a phaseamatic, a Steelcase (commercially supplied rpc's), and regular motors: a big-assed baldor Super-E 10 hp beauty (very expensive), and a current-gluttonous Magnatek, I think.
So I fired up the Steelcase, which gives leg-to-leg variations of about 30 V!! Phaseamtic not much better.
So I used these to fire up the Baldor (just a motor), then *shut off* the Steelcase/phaseamtic, and just measured voltages on the baldor. +/- about
15V, no load, on 240 input. Not bad!!The magnatek also gave good results, but different.
wow.....
I'll have to measure this under load, but the baldor seems like it will solve a lot of my problems--and likely save me $2K+++.
I would spend the money, if I really had confidence in what I was getting. But if all CNC grade rpc's are is a bigger-assed motor, sheeit, I already got those!
Btw, phase-a-matic uses baldor motors, but specially made, and they run really really not-- over 200 deg!!!
Supposedly "real" rpc idlers are not just motors used for their 3rd leg, supposedly different, but at this point, I don't know who/what to believe anymore.
All I know is, that baldor leaves me sig'ly better off 3ph-wise than I was.
I'm still willing to pay for a "professional" solution, but I'm not sure there really is a better one, unless I go with something like Phaseperfect's digital, which not everyone agrees is great for cnc anyway.
Iny idears/comments?