VFD and multiple motors

O

Orion Thomas

Joined
Jan 19, 2023
Messages
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I am wanting to use two different motors, one for my 2x72 and one for a 9" disk, and using a single VFD. KB electronics said this is fine but power must be interrupted going into the VFD before switching or you can fry it. Is there a particular plug to use for that four wire connection? I don't want to use switches to make it impossible to flip something a accidently.
 
Just use a 4 wire plug of your choice. Wire the FEMALE plug into the vfd and the male ends into the equipment.
 
I suspected but I overthink everything and I know just enough about electrical work to know I should usually ask first. Thanks.
 
I have a 4 prong pigtail on my disc. I just unplug and plug in when needed.

You can use a rotary switch box. Turn to off position for a few seconds before switching machines. I think a bunch of people use them
 
I'm completely ignorant of the rotary switch box is this to interrupt power to the VFD or to switch between motors although you do mention unplugging?
 
I believe he is talking something like this. Would be between the VFD and motors. I plan to eventually do this as well. I have a power kill switch between Wall plug and VFD to make sure all power is disconnected though before I switch over. Sequence I'll be using is select the motor I want. Power up the VFD, then ramp up speed. Any changeover do a full shutdown on the vfd, select motor then power back up.

Please - no sales links!
Here is an image of a three phase rotary switch:
1674385285233.png
 
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Running two grinders off one VFD

Ok so I am going to take my old grinder and set up with my SGA. Will add a second grinder for everything else. Who is running another tool off one VFD ? What do I need to know and what additional parts do I need? Thanks
www.bladeforums.com www.bladeforums.com
 
I use a rotary switch to switch between my 3HP 2x72 grinder, 1.5HP drill press and getting ready to add a 2HP 9in disc grinder. The VFD is a KBAC-29, good up to 3HP. I've had no problems for 5-6 years.

 
I did the plug and unplug thing for a couple of years and got very tired of it as I go back and forth a lot. The plug finally started having problems from the frequent switching. At that point I finally broke down and bought a switch and wired it right. I can't emphasize how worth it it is if you think you will be going back and forth very often. It's not that hard and well worth the small cost and time investment.
 
I think it's worth having the switch if you're using the vfd on equipment that is permanently mounted and close to each other.

I've got a small garage shop with a ton of equipment packed in, most of it on wheels.

I use the same vfd for my grinder, lathe, bandsaw and disk grinder, all of which are on wheels. It makes it impractical to just use a switch.

I've got my vfd mounted to a piece of 1/2" plywood with a handle and holes drilled in the top, the holes line up with hooks on all my equipment so that I can easily mount the vfd on all my equipment. Works pretty good.
 
Another method that works well blends Andy's situation with most folks bench mounted equipment.
Use a three position three-phase switch. You want a 1-2-3 switch, not the 1-0-2 type. The 1-2-3 switches cost about $10 on Amazon. It will run three bench machines or two and a socket/cord ... read on.
Hardwire the belt grinder and disc grinder (for example) to 1 and 2, then and wire a female socket on a 10-foot cord to the third position. This allows sending power to another device not on the bench (or mobile device) that needs speed control or three-phase power.
 
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