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

On 2/24/2017 2:19 PM, wrote:
On Thursday, February 23, 2017 at 10:21:35 PM UTC-6, Martin Eastburn wrote:
Good - Uncles was three phase... No VFD. It had a controller or
something that kept blowing up. I supplied snub circuits to him and the
problems went away.

Martin



Unless your Uncle had 3 phase power direct to his shop, or used a rotary or static phase convertor to turn single phase into 3 phase, his lathe had a VFD. There are only a few ways to get 3 phase power. Rotary or static phase convertor. Three phase power direct from the utility company. Or a VFD variable frequency drive. The VFD has the advantage of providing variable drive for a 3 phase motor. The other methods only operate the motor at one speed, full. So the other methods would require pulley changes to vary the speed on a lathe. No variable speed with a dial button.