Cable size - VFD / Capacitor bank

Sj,

I hope that these are two separate applications, because I don't know of any VFD manufacturers who are happy with capacitors on their load side, and capacitors on their line side can cause the applied line voltage to rise above the rated voltage of the drive.

Take the nameplate amps of the motor and size the cables for 125% of this value. For motors fed from a VFD, if the cable length is over 50-feet (15 meters) or if the motor is not specifically designed for use with inverter drives, also include 3% or 5% load reactors sized for the motor.

For the capacitors, check the manufacturer's literature or the NEC for cable sizing. Don't forget to include a suitable disconnect and overload protection. If you are applying capacitors to motors for power factor correction, and the capacitors are placed after the motor starter, you will probably need to change the starter's running overload protection (heater) because the motor will be seeing more current than the starter's heater.

OK? --JMM