Oka, nice explanation.
Just one point to mention. All my single phase 3hp 240V motors are connected to 20A breakers, no issues.
1hp= 746Watts
3hp= 2238Watts
Current = 2238/240/0.8 = 11.7 Amps
For starting current, unlikely that would go above 15 A
For 3 phase divide the above by square root of three and power factor.