The first test run did not go well.
The pony motor spun up the idler and everything switched in as planned. The idler took over and ran just long enough for me to look at the voltages (which seemed about right), about 15 seconds or so.......then the 50 amp breaker tripped.
*^^%^&. So disconnect the idler and do a quick phase to phase check with an ohmmeter: 0.4, 0.4, 0.2. That's not good, I think it has a shorted winding. Maybe that's why the air compressor failed. Headed to the motor shop on Monday, I'll have them put it on the bench. I have no way to properly test a 15 Hp, 3 phase motor in my shop. I really kinda hope it is the motor, at least that would mean I didn't foul something up. It was running unloaded, no caps in circuit. Rated at 15 Hp, 48 amps at full load, there is no way that motor could be drawing >50 amps unloaded if it's healthy, even single phasing.
Here is a couple of pictures of the nearly finish panel. Still have to wire in (gray cable) the current transformers (little black things) for load monitoring.
That's a big ball of wires, wrapped with spiral wrap at the bend.
The back of the door
And the main panel
My son designed and machined a mounting bracket for the current transformers, mounts under the 3 terminal power block.
Here is the design, I'll post more pictures later. Made of UHMW.