Another Switch Question for Two Motors on One VFD

G

Gables

Joined
Dec 20, 2009
Messages
40
I have read various posts regarding running multiple motors from one vfd. I would like to put one of these switches upstream of my VFD to push power to a heat treat oven or the vfd with standard 3 wire, 240v, 30 amp, single phase power. Downstream of the KBAC-27D vfd I would like to put in another of these switches to run one of two 3ph motors. Would this switch work for both? I am new to 3ph wiring and don't quite understand my needs.

http://www.amazon.com/Positions-Cha...Y2/ref=sr_1_16?ie=UTF8&qid=1310750459&sr=8-16
 
Gables said:
I have read various posts regarding running multiple motors from one vfd.

I would like to put one of these switches upstream of my VFD to push power to a heat treat oven or the vfd with standard 3 wire, 240v, 30 amp, single phase power.
No
The 20 amp switch is not rated high enough to handle a 30 amp load.
You may burn the switch running the oven


Downstream of the KBAC-27D vfd I would like to put in another of these switches to run one of two 3ph motors.
Maybe yes. Each motor requires 4 wires. 3 legs and a ground. Just switch the 3 motor legs.
They list 12 pins, which may give you 4 inputs#1, 4 inputs#2 and 4 outputs....but the picture looks like 3 pins per....???

http://www.amazon.com/Positions-Cha...Y2/ref=sr_1_16?ie=UTF8&qid=1310750459&sr=8-16
Click to expand...

3 Positions On-Off-On Changeover Control Rotary Cam Switch 20A
 
Last edited:
For the VFD switch, you don't switch the ground.

Just ground both motors, and switch the legs.

I am no electrician, but I don't think you are supposed to switch a ground, leaving something not grounded when not in operation.
Pretty sure ground should always be ground...
 
Fellhoelter said:
For the VFD switch, you don't switch the ground.

Just ground both motors, and switch the legs.

I am no electrician, but I don't think you are supposed to switch a ground, leaving something not grounded when not in operation.
Pretty sure ground should always be ground...
Click to expand...

I think you're right.
The important part is that the 20A switch will not handle the motor, but not the 30 A oven load.
See if you can get a 20 to switch between motors and a 30 to switch between oven and vfd.
 
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