data to follow:
Rotary converter made with a Heemaf 3Ø 5HP motor rated for 220 / 380 Volts.
The supply is 230 Volts 20 Ampères single phase.
Normally a 3 phase motor is started up in star, when up to speed it is switched to delta.
I reverse engineered the concept of that with a lower 230 Volts voltage to "generate" a higher 400 Volts voltage should be possible, which I prove here with this set up.
Starting the motor in delta with the start capacitors, then switch over to star and energizing one winding with 230 Volts. An excitation capacitor is required to make the 3 phase field while in star( the 8uF 660Volts Siemens Cap)
The motor will stabilize it at around 380 - 400 Volts.
The neutral has to be switched over to the star point otherwise the motor will brake.
An extra pole is required on the delta relay to achieve this.
The opposite is possible too although I have not tried it out is to start the motor in 230V delta, then switch to star and apply the 230 Volts across the star winding.
In this case 127 / 220 Volts 3 phase can be achieved as well.
18 Dec 2010 Crawling is a running state of the motor, that the motor runs at 1/7 of nominal speed and remains running with excess current flow in the windings and can't get itself in correct synch with the mains.