3 phase for a tool with 2 motors

[verbotenwhisky]

Wouldn’t try that. VFD’s like to be ”tuned” to the motor they‘re running. Plus you loose the advantage of variable speed. They are cheap enough to get one for each motor anyway.

I have both static converters and VFD’s in my shop, horses for courses. I also have a 5hp three phase motor I’m hanging onto in case I want to build a rotary converter (actually started setting it up but decided I didn’t need it yet).

john

That is why I said "and phase conversion is all you are planning to use it for." If you plan to use them for a motor control you cannot run more than 1 per VFD. The other issue is the sine wave cheap VFD's are prone to causing which can muck up your electrical power and cause damage to electronics, put 2 together and play the electrical version of Russian Roulette.

If I owned the machine I would either put single phase motors on it or bite the bullet and buy a good quality properly sized RPC.

 

[PNW_Guy]

Considered a VFD for the spindle and a stepper motor for the power feed? A setup can be super simple - we're not talking electronic leadscrew here, though it is, of course an option. Control boxes with forward/reverse and a simple knob for speed are readily available. Some also have extra features like cutout from a signal from a switch, acceleration control and can be whisper quiet with the right driver chip inside. Sometimes the old ways are not the best way.

That's not an option.

There's a single 3 phase cord and plug on the mill and the integrated X & Y axis power feed is also 3 phase. It's not a Bridgeport with a power feed bolted on. It has distinct feed rates, not a dial that shows percent of motor speed.

Sure, it would be possible, but there's no reason for it.

 

[PNW_Guy]

I work on packaging equipment that uses a single inverter to operate 2 unmatched motors simultaneously.
There is no special tuning to the inverter to accomplish this task.
The drive frequency is adjustable, both motors run at the same frequency.
One motor is often 2.2Kw , the motor operating simultaneously is often .25 to .5Kw
I have not seen complications from this non-theoretical implementation

This is the direction my buddy decided to go. I've always heard that you can't run 2 motors on a single VFD, but clearly it can happen.

The spindle and power feeds have their own speed control, and both motors run at a constant RPM. Just like in your example. His electrician is scheduled to feed power to that part of his shop in a week. I'll know soon enough.