Rated current and thermal derating
The 3RW3037-2BB14: That 10 °C step from 40 to 50 °C costs you 5 A — if your panel ambient runs at 50 °C, size the motor FLA against the 58 A ceiling, not the 63 A label. The integrated bypass contact system carries the full motor current once the starter transitions to run state, which drops the thyristor heat load. This means the derating curve above applies to the start duty cycle, not the continuous run current — the bypass handles steady-state.
Terminal assignment and wire sizing
The back clamping point accepts 16... 2 AWG; the front clamping point accepts 18... 2 AWG. For a 63 A motor circuit, you will land 16 mm² or 6 AWG on the main terminals — the dual clamping points let you parallel two conductors per phase if needed. Auxiliary and control circuits terminate on spring-loaded terminals, accepting 2x (24... 14 AWG). The spring cage saves time on control wiring — no screw torque check, just push in the ferrule.
Mounting and clearances
Size S2 frame measures 55 mm wide, 160 mm high, 170 mm deep. Fastening is screw and snap-on mounting to DIN rail — the snap-on foot lets you pre-wire the panel and clip the starter in last. Required clearances: 60 mm upward, 40 mm downward, 30 mm at the side for airflow and wiring access. Mounting position requires a vertical surface within ±10° rotation and ±10° tilt. Pollution degree 3 per IEC 60947-4-2 means it is rated for conductive pollution environments typical of industrial control panels without conformal coating.
Control supply and operating conditions
Control supply voltage accepts 110... 230 V DC — a wide-range DC input that simplifies panel wiring since you do not need a separate AC control transformer for the starter logic. Operating frequency is 50... 60 Hz for the line input. Ambient operating range is -25... +60 °C; storage range is -40... +80 °C. The minimum load is 10 % of rated current — below that the thyristor firing angle may not trigger reliably, so do not use this on a motor drawing under 6.3 A FLA.
Lifecycle stage is current production — this is an active catalog part from Siemens, not a phase-out or NRND line. The SIRIUS 3RW30 series is the standard-performance soft starter family from Siemens. The 3RW3037-2BB14 sits at the 63 A / Size S2 position in that family.