Oct 7, 2013 · 2-2 Size the cables per the VFD rule (which to be clear is 125% of the MAXIMUM RATED input current, not just what you plan to use with the connected motor), then size the breaker per the …

Sep 26, 2017 · Conductor sizing is dictated by the NEC, many VFDs are made in and for places where the NEC is not valid and the rules are different, but WE still must follow the NEC when installing them.

Jun 16, 2022 · You need to size the wire to the VFD at 125% of it's rating. Wire from the VFD to the motor would be 125% of the NEC ampacity for that motor. Use max or less rating for the VFD. 80 …

Nov 20, 2012 · The VFD controls a 300HP motor, 480V, 3 phase. The VFD draws 385Amps. The motor FLA is 357 Amps The designer wishes to protect the VFD with a 400A 100 percent breaker, but he …

Feb 28, 2024 · The code requires you to follow the manufacturers instructions for sizing the ocpd on the inlet to the VFD. You are required to use conductors with an ampacity of at least 125% of the rated …

Jan 23, 2011 · Do you size the branch circuit conductor for a soft start at 125%. 125% of what? Let's put it this way, sizing conductors for motors controlled by soft starters is no different than sizing them for …

Mar 23, 2022 · Attached sketch i have panelboad breaker #1 feeding VFD 20HP rated. The 20HP vfd is feeding 50A fused disconnect at the 20HP motor 480V three phase. My questions are as follows: 1. …

Jun 18, 2020 · The input to a VFD is a sine wave for the voltage but the current waveform is a series of pulses. Line reactors or filters take the edge off of this. I don't think you would gain anything from …

Oct 6, 2017 · A 100HP 125A output VFD will have an input of around 97.6kVA (pulling this off of an Allen Bradley VFD chart). So if that transformer is used ONLY for that drive, it's fine. Sizing a transformer …

Jul 17, 2025 · None of that, however, would change anything with regard to the VFD-to-motor conductor sizing. Again, here in North America those conductors are sized at 125% of the FLC value in a look …