phase converter for Bridgeport

E

eddief

Eddie Fosnaugh
Just bought a 1.5HP Bridgeport Mill with variable speed and now need to get a rotary phase converter or VFD for it.

I read all I could here through the search function and was just seeing if there is anything new out there. Thanks!


Oh ya, ballscrews are NICE!
 
I have a 5 hp rotary phase converter that I'm not using anymore...got a new bigger lathe and needed a bigger one to run both lathes...that I could sell you. It is a Phase-a-Matic, and is still wired up with the 3 phase disconnect. All you would have to do is hook 220 to it, and the machine to the other end and you are running.
---------------Jeff Walker
 
Don't bother with a phase converter, on a single motor machine just buy a VFD. Find Automation Direct on the net, they sell VFDs that only need single phase and produce 3 phase, that will also provide all the motor protection that you will need.
 
I use a hitachi VFC on my 2 hp Bridgeport, works great, but will not give you instant reverse as it takes time to spin up. never been a problem as I don't do power taping and the like. I use a slightly smaller Hitachi unit on my 10" Southbend lathe. Both have worked flawlessly for about 4 years. THe smaller unit is silent, the larger one on the Bridgeport has a cooling fan (like in a computer) and is a bit noisy and annoying. I use the VFC to control direction, but leave it set at 60HZ and use the machine to set speed. Same with the lathe. If you want model numbers, let me know and I'll send you particulars.
 
eddief said:
Okay I have it narrowed down to this VFD drive here...

http://www.kimcontrols.com/item/GS222P0

My question is, since the mill has a variable speed motor, will I be able to change the speed with the turn dial on the mill or will I have to use the VFD?
Click to expand...

You should be able to use either. Which you use is up to you. Running the motor at a constant speed and using the mechanical won't bother the VFD, but if you leave the mechanical adjustment alone and use the VFD for speed adjustment you "may" wear a groove in the pulleys after a while. Using both together will broaden the RPM range and thus the size tools you can use effectively within the RPM limits of the bearings, whatever that is.
 
I have a variable speed Bridgeport and a 3 ph 2 h.p. lathe. A VFD is great on the lathe and the B'port is fine with a Cedaberg 3 hp static phase converter.
I think that a VFD is kind of a waste on a variable speed mill.

Jay, Idaho
 
You may want to be careful about using VFD for speed control on older Bridgepott motor not designed for it. I use the Bridgeport variable speed control system and merely leave the VFD set at 60HZ. Easy on the motor and it has worked fine for years now. Same for my lathe. The Bridgeport has all the speed variablity I've ever needed.
 
Why should I be careful? I've used them on both of my Bridgeport step pulley mills for 8 yrs. If I had a variable speed mill I wouldn't use the variable function as much.
Butch
 
Butch, as I understand it, some higher horsepower AC motors under higher loads do not respond well to off frequency power, especially at very low and very high frequency. Same it reportedly true for inverter power, especially square wave inverters. I don't know the particulars, but was merely passing along advice given to me by another I consider knowlegeable who owns a local industrial electrical supply house and is both a jorneyman electrician and an electrical engineer. I suspect that the low frequency, low speed - high load combination may be a problem with heat or armature brushes as well as high RPM in excess of bearing capacities, but again these are merely my speculations. I'll try to get a chance to speak with the guy who warned me off the practice and report back further.

Regards, Chuck
 
Butch Lambert said:
Why should I be careful? I've used them on both of my Bridgeport step pulley mills for 8 yrs. If I had a variable speed mill I wouldn't use the variable function as much.
Butch
Click to expand...

Older motors do not have as good of insulation in the windings and on the wire as a modern motor. The change came about due to the introduction of VFD's. While the output current of your VFD might be 40Hz, the voltage is switching (PWM-pulse width modulation) at 4-16 kHz depending on the IGBT design. At each transition there is a voltage spike. These spikes can break down the insulation on a motor with insufficient insulation and cause damage to the windings. This is why you see the term "inverter duty" on some motors because they were designed specifically for use with VFD's and have better insulation. Most regular domestic motors made in the last 20 years or so are probably fine. It's the old motors from the 70's on back (or crappy import motors) that were designed before VFD's were popular in small sizes that could have a problem. It doesn't mean that an old motor will fail, but they are more likely to than a newer one when used on a VFD. The only way to find out is to use it.
Greg
 
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