VFD Wiring Question

[simspace]

This week I purchased a used lathe and used mill. Both are 220v / 3 phase motors. I will be adding a 220v circuit to my garage with the hopes of getting both machines and running today.

But I need to figure out wiring, so that both machines can be powered by the 3HP VFD that I purchased, just not at the same time. That is, I will not be running both motors at the same time.

That's my question:

Is there a simple, safe way to wiring up the 3HP VFD to control both machines individually, using a main switch to toggle which motor receives power?

I have watched a bunch of videos regarding wiring up a VFD but there's not much out there on how to set up multiple motors on one FVD.

Someone I know suggested wiring both machines in series after the VFD and put a 3 phase switch on each machine to prevent power from getting to them unless switched on.

I'd love to get your opinions and ideas on how to wire this VFD safely (PDF link).

 

[tjb]

Glad to hear you found some equipment. What did you end up buying?

Regards,
Terry

 

[simspace]

Glad to hear you found some equipment. What did you end up buying?

Thanks Terry, here's my post on the mill and lathe that I purchased this week.

 

[Z2V]

Your VFD will have parameters to be set that are specific to the motor attached. HP, operating voltage, current draw, just to name a few. For the VFD to operate properly these need to be set correctly. Others will chime in but I think you might be better off with a VFD for each motor otherwise you will be changing many parameters each time you switch motors.
Like i said, there will be others chiming in on this.
Congrats on getting your machines

 

[matthewsx]

I would use an outlet and separate cords, but any switches on the machines themselves will be problematic.

Once you pay for extra outlets, switches, or whatever it takes to do this you’ll probably be at the cost of another cheap VFD.

Depending on the wiring of your machines you may want to get a static phase converter.

John

 

[markba633csi]

I believe it's doable, but in addition to the 3 pole switch between the motors and the VFD you will need to program two sets of parameters for the two motors. They may be similar enough that you can use one set of parameters, maybe
Remember that any flaky connections between VFD and motor when running can cause damage to the VFD output stage, this is why VFD output switching arrangements are generally discouraged
-Mark

 

[pacifica]

If you are ok with parameters( maybe a slow ramp up, max low hz torgue, and quick stop) and motors are identical on both machines the simple way would be to unplug one and plug the other one in. would be a shame to ruin vfd,though using that method.
Mark Jacobs is the expert in this area and can tell you the best procedure.

 

[mksj]

I agree with what others have already pointed out, it is not only that the motors are different but also the way that the operating parameters and controls work are different. At the cost of the VFD, it is much more practical to use two separate units. On the mill you would wnat to use what is known as 3 wire control with momentary run/stop buttons, on the lathe they typically use 2 wire which requires a sustained run command in either direction but requires some form of interlock system. Just connecting the spindle wires directly to the VFD is not recommend and also trying to operate the lathe from the control panel on the lathe is not practical. On the lathe you should use an external braking resistor if you are looking at under 3 second stopping times, but depends on the lathe and chuck. The VFD also needs the external braking circuitry for use of the braking resistor. VFD's cannot be used as a direct power source for the mill or the lathe, unless substantially oversized and there are issues with the protection circuity that make it impractical at this level/application.

 

[simspace]

I purchased a second Soyan Power SVD-E VFD. It will be here Monday.
In the end it's going to be easier and safer having a dedicated VFD than try to wire up a complex switch solution.
In the meantime, I'll get all the wiring done and hopefully get the lathe running today.

 

[simspace]

Your VFD will have parameters to be set that are specific to the motor attached. HP, operating voltage, current draw, just to name a few ...

I just discovered on the mill that the plate with the motor spec is missing.
The manual says the motor is rated at 0.5/1 Kw @ 60Khz for spindle speeds 800/1700 rpm.
But have no idea what the current draw is.

The lathe is 1.1/1.4 Kw @ 60Khz for spindle speeds 1450/2820 rpm.
The current draw is 5.4/5.6 Amps.

Based on that data is it safe to assume the mill's current draw is less than 5.4/5.6 Amps?