We have a LV-MCC in our commercial outlet having a 480 VAC, 15 HP VFD with line and load reactors in series with it. The VFD is sized for 22.0 A (normal duty), the motor has a horsepower rating of 10 HP (yes this is comparitivey lesser horsepower than what it should be, but it is to be replaced in future with 15 HP motor) and the circuit breaker is having a trip rating of 60 A. However, the line and load reactor is rated for 25 Amps. With respect to the reactor selection catalogue (the manufacturer's guideline), it is recommended to use the 25 amps reactor (for both line as well load).The catalogue recommends the reactor rating based on the VFD Amps (of course different for normal and heavy duty) rating and not the motor HP. So, with respect to the guidelines mentioned,
- Does upsized reactor will have any adverse effects on the behaviour of the system or affect the life of motor?
- How is the reactor rating decided, is it dependent on VFD amps or the motor HP? (As far as I know, the VFD rating is selected using the FLA rating of the motor and it's service factor, and an upsized VFD wont cause any hindrance in the desired operation of the motor, except the increased cost of VFD.)
- How can I calculate the reactor ampere rating for the specified motor HP or VFD ampere rating?