VFD for Bridgeport - which one?

[mc-motorsports]

I would like to buy a VFD for a Bridgeprort Series 1 2hp mill, 3 phase.

My main goal is do double the spindle speed..
The other thing is I would eventually like to use in conjunction with Mach3 for controlling spindle speed.

Can someone reccomend a VFD for those two needs? I already have 3 phase via a rotary converter which works great. I would prefer to keep the 3 phase from the rotary for the reason of not having to rewire everything.

MC

[mc-motorsports]

Well, I called driveswarehouse.com and ended up ordering SJ200-015NFU2, it's what they reccomended.

MC

[Al_The_Man]

You would not necessarily have to rewire anything, the 240 legs go straight through anyway, usually the 240 is there, even if the RPC is off.
I would only go up to 120hz if it is a 4pole motor, which it most likely is.
I initially had an RPC on my 2hp knee mill before the VFD, now I don't bother to run the RPC.
Al.

[mc-motorsports]

Originally Posted by Al_The_Man You would not necessarily have to rewire anything, the 240 legs go straight through anyway, usually the 240 is there, even if the RPC is off. I would only go up to 120hz if it is a 4pole motor, which it most likely is. I initially had an RPC on my 2hp knee mill before the VFD, now I don't bother to run the RPC. Al.

I gave the tech guy a quick run down of what I have and what I want to do, he said don't run the RPC, it can actually burn up the VFD. He said it would be better off running single phase to the VFD anyway.

Will 120hz double the speed? Will this be half way safe for the motor? I'm honestly more concerned about the motor that I am the spindle. I rebuilt spindles for 9 years, I'll upgrade the bearings and make 100% precision fitment if the spindle fails... Being a 2hp motor, I was told by the local dealer, it's much more expensive to replace vs. the MUCH more common 1.5hp motor, I guess they are different foot prints, ect. But then again, if I took the time, I could put any motor on it and direct drive it vs. using the BP variable speed pullies and what not.

Anyone know how Elrod Machine is controlling the spindle for ridgid tapping? I'm assuming some kind of VFD or AC drive, but with feedback? How much are those drives?

[Al_The_Man]

Originally Posted by mc-motorsports I gave the tech guy a quick run down of what I have and what I want to do, he said don't run the RPC, it can actually burn up the VFD. He said it would be better off running single phase to the VFD anyway.

I would be interested in his reasoning for that statement?
I have run on both 1 ph and RPC with no problems.

Originally Posted by mc-motorsports Will 120hz double the speed? Will this be half way safe for the motor? I'm honestly more concerned about the motor that I am the spindle.

120hz will double the speed, I usually reason that a manufacturer of 4 pole motors will also make their 2 pole motors to the same spec, so the 4 pole motor based on this premise, should run at the same rpm as the 2 pole model.
So far it has worked out OK.
Normally for rigid tapping, it is best to have pulse generator feedback of some kind to the spindle drive or VFD for precise rpm control, and an encoder on the spindle to sync the Z axis servo to.
Al.

[mc-motorsports]

I would be interested in his reasoning for that statement?
I have run on both 1 ph and RPC with no problems.


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He probably wanted me to spend another $100 for the more expensive drive who knows... Just what he told me... I bought into it knowing a RPC has 2 legs from the single phase input and a "wild leg", figured he's probably right? Maybe?

Should I keep the RPC or run straight single phase? He said straight single phase... I'm not an electrical engineer. I do basic wiring and simple schematics, that's about it. I can tell a diode from a resistor from a capacitor from I don't know **** when it comes down to it. Any help is appreciated. I guess I get a 12 month warranty?

[Al_The_Man]

I would run it off 240 1 phase if it is capable of it. You won't have to hear the RPC running!
As I said, thats what I ended up doing with mine.
Its the original 2hp 4 pole motor.
Al.

[mc-motorsports]

This might sound kinda dumb, but I'm not an electrical engineer.... I have the VFD and I'm wanting to wire it up in the morning but I have some basic questions.

I'm going to get rid of the RPC (needed for other machines though) and wire this single phase 220v into the VFD, 3 phase out to the Bridgeport motor.

#1 Do I just wire 220v single phase to the VFD and then wire the VFD to the Bridgeport "forward/reverse" switch? Using the normal switch to turn the spindle on and off? I won't be controlling the speed with Mach3 at this time.
I'm wondering if this will work because I want to run the motor at 120hz. Would the motor start and stop ok with the standard switch between the VFD and the motor? Or would I need to start and stop the motor using the VFD?

#2 Can I mount the VFD to the wall or do I need to mount the VFD close to the machine? Right now, the power wires are over-head in EMT conduit and the machine is 12 feet away from the closest wall.

I've searched CNCZONE and read through the manual, still confused. The answers would probably be obvious once it's wired up and I actually figure out how the VFD works, but right now I'm still confused

[Al_The_Man]

You Cannot, or should not put any switching or disconnect device between the VFD and the motor.
There is no need for the FWD/REV switch as it is right now.
The motor/VFD is controlled solely by either the keypad or external low voltage inputs by contact closure.
The parameters allow different combinations of control of the inputs.
You can either run from the keypad or set up a remote push button or relay arrangement if wishing to run from the machine and the VFD is mounted at a distance from the machine.
If using single conductors in flex from VFD to motor, make sure they are twisted together for EMI reduction and do not forget to run a ground to the VFD and from VFD to motor frame.
It is preferable to keep the VFD as close to the motor as possible to keep conductor length to a minimum.
Al.