View Full Version : 270v 3-phase alternator?

06-27-2005, 11:17 PM
Just found a 3-phase 5kw alternator that outputs 270 volts. I thought about using this to power some 3-phase equipment. The problem is that it's 120hz output.

Is there a way to get this down to 60hz? Wiring? Speed? Will a VFD handle 120hz input?

Thanks, Ken

06-28-2005, 01:44 AM
Just curious--what was it used for in its first life?

06-28-2005, 08:37 AM
There was a line of power hand tools that that required 120 cycle current. They were used on assembly lines and in other factory settings. They were used because they would not work anywhere but in the factory. The owner had to buy and maintain the generator but it was cheaper losing the tools to theft. I think that they were made Chicago Pneumatic and were called 'Hy-Cycle'. The generators were sometimes used to make machines run twice as fast as they meant to. It worked OK for little while.

06-28-2005, 09:46 AM
I don't think any common VFD will handle 120Hz on the input. If this is an M/G set (Motor and Generator connected or on common shaft) you could run the motor with a VFD at half its rated speed to get 60Hz. The rotary speed and number of poles in the alternator detirmine the output frequency. I used to work with 125 kW, 600 Hz single phase output M/G sets used for High speed seam welding.