To be compatible with the coordination study, it should be set at just above the inrush current of the largest connected load on startup. If the breaker is in an MCC then I would follow the old Westinghouse recommended procedure: 1. Raise the inst dial to max. 2. Start and stop the motor. 3. Lower the setting 1 notch each time you restart motor until the breaker trips, then raise the dial 1 notch. 4. Restart motor to prove no-trip. This will be the final setting. This setting should match the trip curves in the study and also takes into account cable impedance, as well.