VFD wire type
Put this on another forum earlier but this is probably a better place because the other is more of a user group and not a DIY builder focused forum.
Could one of you sparkie experts educate me?
Hooking up a new VFD to a new spindle. 220V 3-phase. Have two choices of VFD cable. Which is better?
1) four conductors, each insulated, with shield wire
https://www.wireandcableyourway.com/...vfd-cable.html
2) three conductors (insulated) with three shield wires that touch shield the whole length
https://www.wireandcableyourway.com/...vfd-cable.html
From online reading it sounds like I need to bond the shield to the ground at each end anyway to prevent noise so is that the purpose of the three smaller shield wires that touch the whole length?
Which option above is better for less noise or is there really that much difference for a fairly short run (50') so just go with the cheaper one?
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Re: VFD wire type
The less expensive would be fine. Only connect the shield at the panel end to prevent a ground loop.
EDIT:
I didn't read the specs very well, you want to use the 4 conductor cable, to keep the safety ground isolated from the shield on the motor end. As above only ground the shield on the panel end.
Last edited by Jim Dawson; 03-18-2017 at 03:16 PM.
Re: VFD wire type
Do you really need 12 gauge wire? I used 16 gauge on my spindle and that was overkill.
Last edited by DonFrambach; 03-18-2017 at 03:47 PM.
Re: VFD wire type
From my experience of installing VFD's over a number of decades, I have never used shielded cable from VFD to motor, for the most part, what I have used is liquid seal metallic flex conduit, with TEW/MTW in the flex, the 3ph conductors need to be twisted together with the ground conductor ran along side them (untwisted).
This ends up with the conduit, which is essentially a shield, grounded both ends.
The earth conductor goes to the VFD and continues on to the motor frame.
the effect of grounding and bonding both ends essentially eliminates ground loops.
The definition of a ground loop, BTW is when there is a potential difference between one point of ground and another.
The oldest motor I fitted a VFD to was originally installed in 1959!!
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
Re: VFD wire type
How much current is your spindle rated at? Its in the nameplate. I accidentally ordered a 14GAU VFD cable, 4 conductor and mesh shielding and it was a huge diameter cable.
Based on other member's recommendation and like DonFrambach, I ordered a 16AWG/4C cable from McMaster-Carr at a buck 'n a half per foot. Rated at 18Amp @86° F 600V.
No-Conduit-Required Double-Shielded Control Cable
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