phase converter

[contractdesign]

Is anyone out there powering a bridgeport boss 1985 era machine, that does not have 3 phase power, with something other than a rotary phase converter. I've tried a static converter, no dice, and an AC Tech drive (smoked the transformer). I'm worried about the old motor windings. My machine runs on 230/3/60.

[RGeo]

I am not familiar with the particular Bridgeport machine you have. I do know that if you are just trying to run a 3 phase motor, a static phase converter will work and there are AC Tech drives that will work on single phase to run 3 phase motors.
The problem is if you are trying to run a machine with more than just a 3 phase motor, such as a CNC or machinery containing a control transformer etc.
When using a static phase converter, make sure that the two legs powering the line side of the transformer are the same as the incoming legs, do not use the generated leg to power control transformers.
When using an AC Tech VFD, only use it to run a motor, you cannot run additional devises with a VFD. I am being general, again I do not know your specific machine, what does the circuit power?

[contractdesign]

I am tring to run the 3 hp motor, and the relays for the motor controls. (Air motor for variable speed, start stop, and brake) The cnc side is seperate (mach 3 / gecko rebuild). I tried an AC Tech drive and the power transformer in the back that runs the control side of the Bridgeport started to smoke. The xformer still works, but I was advised that if I updated the xfromer the old motor windings would eventually fail because of the voltage output of the AC Tech drive.

[RGeo]

Contract Design,

It sounds like the mill itself is fairly simple. I would say that you could still use the AC Tech unit assuming it is rated for 1 phase in and 3 phase out.

Please use the proper Lock Out Tag Out procedure to insure your safety.

Connect the two hot wires from your 1 phase to the machine. Make sure that you are connecting to the two legs that feed the line side of your control transformer. Leave the other lead unwired. You would then need to connect the AC Tech unit between the motor starter and the motor.

You could then control the AC Tech a couple of ways:
Simple wire the unit so that the unit starts as soon as power is applied, you should be okay because you can shut down the unit though the E-stop and kill the source power. By using this method you will get an under voltage alarm every time you turn off power, it will then require a period of time (10-15 sec) for the alarm to clear then you can restart the unit.

You will have to remove the brake wires from the junction with the motor and wire them in parallel with the input to the AC Tech unit, (on the bottom of the motor starter). This will allow the brake to still operate when the E-stop is hit. Do not power the brake with the output of the AC Tech unit.

There is a way to turn the output of the AC Tech unit independently after your machine start circuit is energized. I do not recommend this method. I feel this type of control could lead someone to coming in contact with the spindle or tool with only electronic control as his or her safety. It is safest to rely on the E-stop when preparing to touch the spindle or tool, this way the spindle motor is truly deenergized.

It is true that older motors may not last as long as VFD rated motors when connected to a device such as the AC Tech, but many older motors last just as long. What do you have to loose?

Again, whenever you are doing maintenance or upgrades to a machine like this, always use the proper Lock Out Tag Out procedure.


Good Luck!!

[morbius]

I do not know if this helps or not, but this is what I am using to power 3 phase stuff on my bridgeport http://www.americanrotary.com/rotary...onverters.html (using 7.5 HP version). The remaining functions that are normal 120VAC are powered by standard outlets with surge surpression.

Cheers,
Roberto

[RGeo]

I agree with Morbius. Rotary phase converters are a cleaner and more surefire solution than either a static phase converter or a variable frequency drive. The benefits of using a VFD is electronic speed control, reduced in-rush current and the possibility of torque control. The down side are, funky wiring (in your case) and the possibility of line disturbances. I do see that you have speed control through an air motor.

I would opt for the Rotary if you can spare the money.

I was trying to help you out using parts you seem to already have.

RGeo

[contractdesign]

I am using a rotary now, I'm just tired of the noise.

[morbius]

Originally Posted by contractdesign I am using a rotary now, I'm just tired of the noise.

Then you might want to look here http://www.americanrotary.com/static...onverters.html and contact these folks. There are very helpful ! Kinda interesting, I and several friends are using rotary and and they are whisper quite.

[RGeo]

Contract Design,

I still think you can use the AC Tech or the static phase converter, just power the motor with AC Tech. Or if you wish to use the static make sure the original legs of power are powering your single phase stuff such as your transformer and motor brake. The created leg should only power the motor in other words.

RGeo