VFD and Servo in the same conduit?

[Murphy625]

Can I get away with running the power cables of a VFD and a servo motor in the same metal conduit if both cables are shielded?

The 2 motors are never operating at the same time but they are 50 feet away from the control box and only 24 inches from each other.

The encoder cables are kept seperate from power.

My main worry is that the high frequency emissions from the VFD will have a negative effect on the servo drive even though the servo is not running at the time.

Could I be running into a problem designing it this way? Or will the shielding on the wires and the fact that the motors never run at the same time nullify any worries?

Thanks!

 

[Skogsgurra]

Despite your handle - which implies that you should expect the worse to happen - I can assure you that you are completely safe from an EMI point of view. Power cables can take a lot more beating than signal cables can. Or rather, the equipment at their respective ends can take it.

With shielded motor cables you actually have two EMI barriers between cable A active conductors and cable B conductors - and vice versa. You will probably never see anything above a few hundred millivolts and with a high Thevenin impedance at that. So nothing can happen. But keep the signal cables out of that conduit.

 

[DickDV]

Hee's a second vote, exactly as skogs has stated

 

[Murphy625]

Thank you!!!

 

[REDDOG]

Code requires the cables have the same voltage rating and the encoder is listed for the votlage of the system. Can not mix power and power limited system in same conduit. Shields are good for high frequency but not so good at 60 hz.