Jim
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This is my second phase converter. I disassembled my my first phase converter because it did not have enough power to supply my Hobart CyberTig welder.
The second one has not one, but two idler motors: a 10 HP motor and a 7.5 HP motor. They are started in a clever arrangement: first a 10 HP motor starts with capacitors labeled 1-3 connected. These capacitors act as starting capacitors.
If 10 HP is not enough, I press a button (not yet available, I tested with a wire), and the 7.5 HP motor comes up. Connected to it, to legs 2-3, are two more capacitors, which means that all four caps become run capacitors -- two between L1 and L3 and two between L2 and L3. It has a very nice effect on vibration.
See this this excellent article on making homemade phase converters.
I used an enclosure from a defunct Ferrups UPS, two used 3 phase motors, and a Allen Bradley size 2 starter for the 10 HP motor.
