What the 45 A rating means for your motor circuit
The Siemens 3RW4036-1TB05 is a SIRIUS soft starter rated 45 A at 40 °C — that is the continuous motor current it can handle in a standard 40 °C panel environment. The 45 A figure applies at 50/60 Hz, meaning it works on either line frequency without a derate. The integrated bypass contact system means that after the start ramp the thyristors are shorted out, eliminating heat dissipation in the power section during run. That keeps the enclosure cooler and lets the soft starter handle continuous duty without oversized heatsinking. The adjustable current limitation lets you set the start current anywhere above the minimum load of 20%, which is useful for gentle starts on conveyors or pumps where mechanical shock matters. Motor overload protection is built in, so you do not need a separate overload relay for the motor branch circuit. Intrinsic device protection covers the soft starter itself against overtemperature and overcurrent faults. The red fault signal display gives a clear visual at the cabinet door when the unit trips.
Mounting and wiring in the panel
Size S2 means the physical footprint is 55 mm wide, 160 mm tall, and 170 mm deep. Clearance requirements: 60 mm above, 40 mm below, 30 mm at the sides. Main circuit connections use screw-type terminals. The power wiring accepts 2x (1.5... 25 mm²) stranded or 2x (0.5... 2.5 mm²) solid conductors. Auxiliary control wiring uses 2x (20... 14) AWG. Maximum motor cable length is 300 m — beyond that, reflected-wave stress on the motor insulation becomes a concern even with a soft starter.