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Wire selection for primary and remote switching on VFD...
- Thread starter FOMOGO
- Start date
- Joined
- Feb 2, 2013
- Messages
- 3,820
You may wish to use 12 gauge copper stranded wire for 3hp on the input and output.
Control wires can be smaller say 16 or 18 gauge as they aren’t carrying very much current.
Unless you’re operating high end electronic equipment , shielding is of little concern or consequence
Control wires can be smaller say 16 or 18 gauge as they aren’t carrying very much current.
Unless you’re operating high end electronic equipment , shielding is of little concern or consequence
- Joined
- Feb 2, 2013
- Messages
- 3,820
If your cables are in very close proximity to the dro, there is a possibility of emf interference.
If a few inches of proximity is allowed between the cables of the vfd and the dro, you shouldn’t have trouble
If a few inches of proximity is allowed between the cables of the vfd and the dro, you shouldn’t have trouble
FWIW the electrical code (here) states that you need to have primary feed capable of full rated power of the VFD, so #8 it seems a bit silly but I think their rationale is that under certain fault conditions the VFD could continuously pull much higher current than the #12 would support. That's assuming the breaker would be capable of providing said current. In practical terms 3HP = 17A @240V full load, so #12 and a 20A breaker would support it. Another rule is branch circuit should not be loaded more than 80% of breaker so a 20A breaker and #12 copper will work but will violate the 80% rule. If it were me I would consider #10 especially if the breaker is any significant distance from the VFD. If you do use #12 copper make sure the breaker is 20A max.
If there was ever an electrical "issue" with insurance involved they may be looking for an excuse. I'm not up on the code state side, but I imagine the code is pretty similar.
Edit: Armoured cable may help somewhat with EMI. Keep the cable between the VFD and motor as short as possible that's the noisy cable with the sharp edges that will produce most of the electrical noise.
If there was ever an electrical "issue" with insurance involved they may be looking for an excuse. I'm not up on the code state side, but I imagine the code is pretty similar.
Edit: Armoured cable may help somewhat with EMI. Keep the cable between the VFD and motor as short as possible that's the noisy cable with the sharp edges that will produce most of the electrical noise.
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