Hi FEG
The 3RW 4446 looks about right since it has a heavy duty class 30 rating of approx 200 amps. Note that the starts per hour will be limited so check the Siemens info.
Setting options include torque control but suggest you use current limit with voltage ramp as an initial setting...
The fact that the motor is a 6 pole helps since the starting torque will be relatively higher. Also an old motor is likely to have good thermal capacity. Good to see you are over rating the soft starter, one with 2 or more starting profiles would allow for starting off or on load.
Agree with most of the comments, I would only add that a thermistor relay would be able to detect if the motor windings became too hot.
A conventional overload relay would not detect over temperature, only over current!
Replacing a fluid coupling with a soft starter is possible but be careful with the Selection of the soft starter, you will probably have to use higher ratings than for a standard application like a pump for example. When a motor is started using a soft starter the starting current will be about...
