Shielded vfd cable

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reyamkram

Senior Member
Location
Hanover park, il
I have a Belden 29501F VFD cable 4C14 when I was in the drive cabinet I noticed the shield for the vfd cables are not connected and if I'm not mistaken The Shield is supposed to be connected on each end is that correct and we have been having issues with motors sometimes they get real hot and burn out and we need to replace them type of motor
Baldor motor 2 HP not an inverter Duty
Any and all information is very much appreciated thank you
 
Yes, you need to ground both ends or the shields on VFD cables. It’s different from instrumentation signal and communications cables where you only want to ground one end. In comm/signal cables you are using the disks to protect against external noise getting IN to the wires. With VFD cables, you are creating a faraday cage around the load wires to keep the EMI and RFI from getting OUT of the wires into other things.

But their effect on preventing motor damage is a minor benefit, mostly just from being triplexes (twisted). Your motor issues are not likely related to the lack of shield grounding.
 
Jraef said:
Yes, you need to ground both ends or the shields on VFD cables. It’s different from instrumentation signal and communications cables where you only want to ground one end. In comm/signal cables you are using the disks to protect against external noise getting IN to the wires. With VFD cables, you are creating a faraday cage around the load wires to keep the EMI and RFI from getting OUT of the wires into other things.

But their effect on preventing motor damage is a minor benefit, mostly just from being triplexes (twisted). Your motor issues are not likely related to the lack of shield grounding.
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Thank you very much for your reply at the company I work for we did discuss replacing the regular induction what inverter Duty Motors if I'm not mistaken they can handle the heat better and their frame is designed kind of like a heat sink and thank you again
 
In audio circuitry, cable shields are always attached to metal chassis's at their connectors. Thus they act as an extension of the chassis.
 
ptonsparky said:
What voltage? What distance? Are you using load reactors? Is the overload setting correct? Are you sure it is not a mechanical issue
Get inverter duty motors.

I've never used that cable, but would think at least one end for the shield. Drive end. The EG conductors are connected. Correct?
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The voltage is 480 there are no load reactors there is seven individual induction Motors the closest one is 2 ft and the furthest one is 35 ft from the drive panel as far as the overload the engineers did not set up overload parameters inside the drive because they would be going off a lot it's an experimental machine that they've been experimenting for last year the motors drive a conveyor again thank you for your reply
 
reyamkram said:
The voltage is 480 there are no load reactors there is seven individual induction Motors the closest one is 2 ft and the furthest one is 35 ft from the drive panel as far as the overload the engineers did not set up overload parameters inside the drive because they would be going off a lot it's an experimental machine that they've been experimenting for last year the motors drive a conveyor again thank you for your reply
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Each motor pulls about 1.5 to 1.8 amp each leg
 
reyamkram said:
The voltage is 480 there are no load reactors there is seven individual induction Motors the closest one is 2 ft and the furthest one is 35 ft from the drive panel as far as the overload the engineers did not set up overload parameters inside the drive because they would be going off a lot it's an experimental machine that they've been experimenting for last year the motors drive a conveyor again thank you for your reply
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That answers why.
I would expect motors to burn up if the amperage is not monitored.
Check the operating amperages and install a larger motor if need be.


I see the 1.5 to 1.8 amps but still no overload setting and they expect it to exceed FLA frequently.
Expect motor failure.
 
reyamkram said:
The voltage is 480 there are no load reactors there is seven individual induction Motors the closest one is 2 ft and the furthest one is 35 ft from the drive panel as far as the overload the engineers did not set up overload parameters inside the drive because they would be going off a lot it's an experimental machine that they've been experimenting for last year the motors drive a conveyor again thank you for your reply
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So do you have 7 motors and 7 VFDs? Or 7 motors running from ONE VFD?

If you have multiple motors running from the same VFD, you absolutely must have individual motor protection for each motor. If each motor has its own VFD, but the motor size information was not programmed into the drive to set up the protection, the drive is likely not running them correctly either. That can absolutely lead to burning up the windings.

No amount of shielding will fix a lack of attention to details…
 
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