What is your duty cycle for the application...
What we call "Supercharging" is using a 460 VAC VFD with a mtor wired for 230 VAC rather than 460. And the VFD has to have a HP rating of twice the motors HP rating. There is some gain to doing this relative to obtainable speeds.
I always calculate the required RPM/Torque/Gearbox etc then choose a motor size and VFD accordingly. I fail to understand this process of supercharging.
I realize the motor doesnt know or care what size it's suuposed to be. up until it saturates and/or melts, a 2HP motor is only good for 2 HP no matter how you manipulate the voltage / current etc.
Supercharging – Hands On Experience
I am a long experienced industrial electrician. If you told me to intentionally miss-wire a 3-phase motor to 240vac, while knowing that the system is 480vac, I would tell you that this is guaranteed to FRY.
But, a customer had a unique application. They needed to reduce the time of transport on an assembly line. The motor only needed to run about 15 seconds out of 60 seconds, so approximately 25% duty cycle.
I was EXTREMELY reluctant to Supercharge. But I went to a LAB with the VFD vendor, and we played in the lab.
I went to the plant, which is a critical supplier, so failure was not an option. In five minutes, I changed the connections in the motor, and modified three parameters in the drive and we ran the motor to TWICE the rated RPM all day long. After running the motor this way, I personally touched the motor, it was cool to touch, or almost less than room temperature.
I am a believer in Supercharging.
Here is the theory: A 3-phase motor will develop full torque at 60hz (1725rpm) and give it’s best performance at that level. If you were to push beyond 60hz, which if a simple conveyor, that you might get away with it.
But if the motor has a substantial mechanical load, when you exceed 60hz, there is torque-slip, and the motors actual horsepower will be reduced.
The purpose of Supercharging is to intentionally miss-wire the motor to DOUBLE the windings. The motor is protected because entering the correct parameters into the VFD will CURRENT limit the power to the motor and prevent it from destruction.
When you miss-wire the motor, you achieve full horsepower and torque all the way up to 120hz.
The only thing we were instructed to do, was verify with the supplier of the equipment, that it would be ok to run at twice the intended speed (120hz / 3600rpm) for “x” amount of time.
Our mechanical motor/drive train vendor approved in writing, and the system has run years without issue.