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VFD Wiring Question

AmericanMaker

Aluminum
Joined
Nov 23, 2020
Location
Franklin, TN
I just purchased a used lathe and used mill. Both are 220v / 3 phase motors. I hope to get them up and running today.

Today I will be adding a 220v circuit to my garage.

I need to figure out wiring so both machines can be powered by (but not at the same time) the 3HP VFD that I purchased. 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?

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 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.

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

 
There is a good reason why your VFD instruction book makes no reference to powering more than one motor with one VFD. You should toss the book and wire it the way you want to. There is no teacher like experience.
 
Are the two machines equipped with identical motors? The VFD needs to have some parameters set that depend upon the motor characteristics. You probably do not want to have to change the parameters when you change machines. If the motors are different, consider using two VFD's.

A simple way to set up one VFD to run more than one motor is to equip the VFD outlet with a four wire grounded three phase receptacle with the current rating that is appropriate for your load. Then equip each machine with a power cord made of SJO four conductor wire of the gage that matches your current and a plug that fits your VFD receptacle. Probably cheaper than a complex switch and totally foolproof as far as preventing both machines from running at the same time.

If one or both motors are rated 1 HP or less, you can get a VFD that will run it from 110/120 V single phase power (any wall outlet.) It will probably be cheaper than a 3 HP VFD and a lot easier to wire.

Larry
 
You might be able to wire them both to the same VFD somehow but your toggle switch might get complicated as you'll have to channel not only the three phase power but all the functions as well such as speed/reverse/start/jog etc.

Why not use that unit on your mill and get a cheap ABB ACS55 for the lathe? I've been using one on mine and they work great.

ABB ACS55-01E-04A3-2 inverter drive 1HP | eBay
 
Last edited:
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.
 
i have a "carry-around" vfd that i run several machines from when needed. no problems so far, i left everything on default.
 
Vfds are so cheap that you should buy one for each machine and wire them permanently


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