shaggy
Hot Rolled
- Joined
- Sep 29, 2010
- Location
- Oakland CA
...or, POS static converter won't properly run VN12(!)
Long story short... My new-to-me Van Norman #12 w/ GE 1-1/2 hp 3 ph. motor - runs just 'OK' at the slower speeds on a Phase-A-Matic PAM-300, which came w/ the machine, but w/ that setup will not pull the two highest spindle speeds.
So I hooked up a 3500rpm 3HP 3-phase motor as idler motor, using the PAM-300 as starter. I'd hoped even this bare-bones RPC would be a vast improvement, however it only just pulls the second-highest speed, but still not the top speed.
I haven't yet rigged run caps or compared legs - it was a quick and dirty setup, by which I hoped to see some improvement over the static converter.
I'm not sure w/ this setup if the PAM is completely out of circuit once the idler motor is running (Previously I'd tried switching the wild/center leg OFF with a toggle switch, to no discernible effect).
A few thoughts.. the VNs 1-1/2 horse motor is getting pretty light-on when compromised by a static converter. Add to that the VN12s helical drive spindle and gearbox, which require substantial torque to get in motion.
I have no illusions about the static converter. It's basically crap, but probably good enough for starting an idler motor.
What I don't understand is why the 3HP idler motor is (so far, and set up the way it is) providing such limited improvement.
Next on my list is a/ make the idler motor remote -- the din of it up close prevents hearing any problem in relays and switchgear, and b/ measure the 3-ph legs once the setup is underway and under load. Maybe add basic run caps, nothing fancy.
Speaking of run caps, what sort of values are we talking about for a ~3HP rig? I see up to 150uF added to the legs on one design. That is a lot of run caps - I'm used to seeing on the order of 3uF, 7.5uF for oil-filled -type motor caps.
I like the idea of keeping the machine, motor and switchgear original, so a VFD has little appeal (though I'm open to persuasion).
But I need this (basic as possible RPC) to be no-fuss. I don't want to get anal about precision-balancing run caps, etc. I believe an RPC can be as simple and effective as I've read, and that I'm almost certainly missing something.
Thanks for any feedback!
Long story short... My new-to-me Van Norman #12 w/ GE 1-1/2 hp 3 ph. motor - runs just 'OK' at the slower speeds on a Phase-A-Matic PAM-300, which came w/ the machine, but w/ that setup will not pull the two highest spindle speeds.
So I hooked up a 3500rpm 3HP 3-phase motor as idler motor, using the PAM-300 as starter. I'd hoped even this bare-bones RPC would be a vast improvement, however it only just pulls the second-highest speed, but still not the top speed.
I haven't yet rigged run caps or compared legs - it was a quick and dirty setup, by which I hoped to see some improvement over the static converter.
I'm not sure w/ this setup if the PAM is completely out of circuit once the idler motor is running (Previously I'd tried switching the wild/center leg OFF with a toggle switch, to no discernible effect).
A few thoughts.. the VNs 1-1/2 horse motor is getting pretty light-on when compromised by a static converter. Add to that the VN12s helical drive spindle and gearbox, which require substantial torque to get in motion.
I have no illusions about the static converter. It's basically crap, but probably good enough for starting an idler motor.
What I don't understand is why the 3HP idler motor is (so far, and set up the way it is) providing such limited improvement.
Next on my list is a/ make the idler motor remote -- the din of it up close prevents hearing any problem in relays and switchgear, and b/ measure the 3-ph legs once the setup is underway and under load. Maybe add basic run caps, nothing fancy.
Speaking of run caps, what sort of values are we talking about for a ~3HP rig? I see up to 150uF added to the legs on one design. That is a lot of run caps - I'm used to seeing on the order of 3uF, 7.5uF for oil-filled -type motor caps.
I like the idea of keeping the machine, motor and switchgear original, so a VFD has little appeal (though I'm open to persuasion).
But I need this (basic as possible RPC) to be no-fuss. I don't want to get anal about precision-balancing run caps, etc. I believe an RPC can be as simple and effective as I've read, and that I'm almost certainly missing something.
Thanks for any feedback!