Simple soft start for high power mains device
[This diagram is close but has too many parts:K1 and K2 are terminal block - or large wire nuts. K1 goes to what should be a 20 to 30 amp 250 volt slow-blow fuse. Assuming Re1 has a 120VDC coil, R1=R2=R3 = 2.2K ohm 3 watts each. C1 can be omitted as can C2. B1 can be a bridge rectifier with a 1 amp 600 volt rating, or make one from 4 1N4007 diodes. C3 can be 47uF 150VDC, enough so Re1 does not chatter. Increase C3 value if longer delay time is needed. Re1 should be a relay with a 120VDC coil (common) and contacts rated for 20 to 30 amps 250VAC. The high current rating will ensure a long life. R4, R5, R6, R7 should be 2 ohm 300 watt ceramic resistors mounted to a panel or on a fiberglass threaded rod. They take some of the punishment if the motor stalls, giving time for the fuse to blow. I would suggest 600 watt resistors but they get expensive (in case the motor is jammed and cannot rotate). These are all bulky brute-force parts designed to last even if the motor stalls. I suggest adding a thermal cut-off next to R4-R7 unless it is built into the motor.  ]