3Ø Rotary converter 240 - 330 - 500 Volts
Three Phase rotary step-up converter.
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In the beginning of the video.
Starting a 5 HP 3Ø motor from a 230-240 Volts single phase supply, with Capacitor aided phase-shift.
Create a spinning reserve for driving other 3Ø motors.
I used some old TV electrolytic Capacitors rated at 400 Volts, back to back, to make a 200µF AC rated starting capacitor. That works very well and hasn't failed after 40 starts at this stage.
Normal practice is to start 3Ø motors in star, delta.
In this case I need to step up the voltage from 230-240 V to 415 Volts.
Depending upon loading, voltages obtained from the 3HP 3Ø idler motor are between 330 Volts, loaded with a 5 HP motor as load, and 480-500 Volts with no load.
Excitation Caps are required. In this case 10µF 3Ø Cap and two 8µF 660 Volts Caps are used to get the 500 Volts.
In the second part of the video, the 3HP idler motor (light green) is used and started in delta and switched to star to get the higher voltages. Then the 5HP (blue) motor is added as a load.
The 5HP motor is happy to start at 3 x 230 Volts.
The other way around is better, 5HP idler and 3HP load but I like testing to the extreme limits of the design. It works although sometimes the switch has to be flicked a couple of times.
At one stage the idler motor ran at 3 x 127 Volts 3Ø, and was still able to start the 5HP load motor.
I am sourcing some more 400V TV Capacitors and want to be able to start a 7.5 HP motor as the base load idler.
I will provide a schema in the next video with the concept of the contactor set up..