OK. He had 3 phase power straight from the utility company to his shop/machines. He used the device you describe to get variable speed for his lathe with a 3 phase motor. Not a VFD to provide 3 phase power and the variable speed from single phase power on the input side. I would guess devices now days that need variable speed and get 3 phase power on the input side have a better way to get that. Maybe a VFD can take 3 phase on the input side and produce 3 phase on the output side for the motor and provide variable speed too.


On Friday, February 24, 2017 at 8:53:37 PM UTC-6, Martin Eastburn wrote:
As I recall his was not a VFD it was a Vacuum tube speed controller
using waveform shape. The parts blown were replaceable. He had
3-phase. He was very wealthy and built a 3 story metal shop for his big
motor home and the rest for an office and shop. Two others got smaller
machines in the class and had a little club. He is now at rest
in a family site on the property.

Martin