Centroid Community CNC Support Forum

Is there a VFD that has enuf to power the 220 side of the machine by just connecting to the top of the fuses and my 400s panel would run as normal? Meaning I would not have to run the control wires from the DC 310 to the VFD.
Or do I just go with a rotary and power it that way?
3hp spindle motor.
I’ve read conflicting blogs on this.

I am a bit confused...I think you are asking if you can use the same power feed to both the control box and the VFD. That will work fine. That gives the VFD power, but unless you plan to run the motor completely manually, you will also have to run control wires from the controller to the VFD, to coordinate the motor with the control.

In short, a VFD needs a power input. It then needs to be told what to do with the power, in the way of what speed and direction you want the motor to run. This can be done with buttons on the VFD in a completely manual way, but usually you let the controller "talk" to the VFD through 18 gage control wires so speed and direction...and emergency stop...can be handled together with the job being run. Try to imagine running a program that goes wild, so you hit E stop but the spindle keeps turning at 5k rpm in your part.

I think RLW was asking about putting a VFD upstream of the entire control; feeding the VFD output into the 3-phase supply terminals of the M400S control cabinet; and continuing to use the reversing contactor set that is already in the cabinet to turn the spindle on and off.

That is a bad idea for a variety of reasons. Wire the VFD downstream of the disconnect, and use it to directly, and only, power the spindle motor.

Completely agree with Marc. VFD downstream of the cabinet disconnect switch and its fuses.
Can you show pictures of your cabinet including the Disconnect switch and fuses? What print number do you have? We can look it up.
3hp VFD's are available to drive your spindle motor from 220VAC Single phase. Automationdirect.com GS2 or GS3 series is one source.
If you want the control to control spindle speed, you WILL have to run the control wires from the control.

Thanks for the input. I have access to a rotary phase converter and maybe will go that route for now.

RLW - the rotary phase converter is the way to go unless you want to convert the whole machine to single phase power. This usually entails adding smaller VFD's for ancillary motors like the coolant pump and conveyors, or swapping those motors out for single phase motors. For fractional Hp motors, it's often cheaper to replace the motor than to purchase a VFD. If you go the VFD route, you will need a separate VFD for each 3-phase motor - you cannot run two motors from a single VFD.

As many have already pointed out, you cannot use a VFD as a replacement for a rotary phase converter. However there are now companies producing digital phase converters for this purpose that can replace the rotary phase converter and the extra, large motor that goes along with it - see https://www.phasetechnologies.com/produ ... se-perfect.

If the spindle is only 3HP, I would go with a VFD to control just the spindle. A rotary is going to be MUCH more money.

Marc, is he going to need anything special to connect it to his vintage control?

RLW, can you post a report or the Centroid Serial number usually found on the back of the console or the control cabinet? Do you have a schematic? If so, what is the drawing number?

A DC3IO has all the necessary hardware for spindle speed control.

There is a slight chance that he will need an additional software unlock code for programmable spindle speed. There was a brief period around 1999 - 2003 or so when Centroid charged extra for that, but I don't recall exactly when that ended.

If you enter a command like "M3 S1200" at the MDI prompt, and it tells you something like "option not available", then you don't have the unlock, and need it if you want programmable speeds.

My guess is that K20334 shipped sometime in 2005, and includes programmable spindle speed capability.

The attached schematic shows generic inverter connections for a DC3IO system.