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power wiring practice of variable frequency drives
- Thread starter dlrd
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BAHTAH
Senior Member
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- United States
Re: power wiring practice of variable frequency drives
No special wire required for VFD. Installation may be shielded or unshielded. The manufacture publishes the maximum conductor size for a specific drive and there are distance limitations to consider between the drive and motor which are also published in the manufactures installation manual.
No special wire required for VFD. Installation may be shielded or unshielded. The manufacture publishes the maximum conductor size for a specific drive and there are distance limitations to consider between the drive and motor which are also published in the manufactures installation manual.
Re: power wiring practice of variable frequency drives
One other item to keep in mind about VFD installations, most VFD manufacturer's only provide 60 degree C lugs for their equipment. If you use THHN wire and assume 75 degree C ampacity rating then you might come up a little short on wire capacity at the lug. Learned this one the hard way.
One other item to keep in mind about VFD installations, most VFD manufacturer's only provide 60 degree C lugs for their equipment. If you use THHN wire and assume 75 degree C ampacity rating then you might come up a little short on wire capacity at the lug. Learned this one the hard way.
tony_psuee
Senior Member
- Location
- PA/MD
Re: power wiring practice of variable frequency drives
Provided the wire meets NEC 430.22(A). This may be more of an issue on the drive input side as it is 125% of drive rating, not motor nameplate. I would strongly suggest reviewing the recommended grounding instructions and following them. Although special cables are not required, depending on distance between the motor and drive may be worth using. The last feedback I got from a VFD OEM was their recommendation is to use conductors wrapped in foil and terminate the foil at the motor ground and VFD ground to help reduce/eliminate high speed switching frequency carrying into the motor.
Provided the wire meets NEC 430.22(A). This may be more of an issue on the drive input side as it is 125% of drive rating, not motor nameplate. I would strongly suggest reviewing the recommended grounding instructions and following them. Although special cables are not required, depending on distance between the motor and drive may be worth using. The last feedback I got from a VFD OEM was their recommendation is to use conductors wrapped in foil and terminate the foil at the motor ground and VFD ground to help reduce/eliminate high speed switching frequency carrying into the motor.
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