Advantages/disadvantages of VFD cable.

[jconnolly]

Is it a signficant advantage to use VFD cable (such as Belden 29502)?

What are the advantages or disadvantages compared to just using individual THHN or eqiv. conductors.

I'm running VFDs to three 11KW (15HP) motors through the same 2" conduit (under concrete floor) along with conductors for a fourth 4KW (5.3hp) motor not on a VFD. Conduit is 19' (6M) to a junction box that breaks out to the four motors.

 

[controlsdude]

If you have mulitple VFD's going to motors and your running the wiring in the same conduit, I would recommend using the VFD cable. You would get noise problems created by using the THHN in the same conduit.

Its better to have the wiring ran in seperate conduit or in the same conduit but with VFD shielded cable.

 

[dpc]

The output of a VFD contains a lot of high frequency energy that can cause all sorts of interference especially with analog signals and low-level digital signals running nearby. The normal power conductors function as a very nice antenna to radiate this RF noise. The special VFD cables have shielding and ground conductor configurations to reduce the radiated energy.

STEEL conduit will certainly help reduce EMI from the conductors (if it is properly bonded), but PVC conduit, even in concrete, will not reduce the EMI much.

 

[rovineye]

Disadvantages can be cost, weight, size, availability for some.