The Siemens SIRIUS 3RT1045-1AC10 is a Size S3 power contactor rated for 37 kW at 400 V in AC-2 duty and 66 A in AC-4 duty — the AC-4 figure governs reversing and plugging applications where the contactor makes and breaks stalled rotor current, so that 66 A is the number to size for jogging or inching circuits. The contactor measures 146 mm high by 70 mm wide by 139 mm deep, occupying a single S3 slot on the rail — plan for side-by-side mounting (supported) if you need to gang multiple contactors for a star-delta or reversing starter.
AC-2 at 400 V delivers 37 kW — this is the rating for slip-ring motor starting where the contactor closes on a resistive rotor circuit, so the current inrush is moderate and the contactor sees reduced electrical wear compared to AC-4. Maximum operating cycles per hour vary by duty: 1 000/h in AC-3, 900/h in AC-1, 400/h in AC-2, and 300/h in AC-4 — the AC-4 limit is the binding constraint for high-cycle reversing conveyors or press drives.
Solid wire accepts 2x (0.5... 1.5 mm²), 2x (0.75... 2.5 mm²), max. 2x (0.75... 4 mm²). Stranded wire accepts 2x (10... 50 mm²). Solid or stranded accepts 2x (2.5... 16 mm²). The 50 mm² stranded capacity on the main terminals suits the 66 A AC-4 rating without needing terminal reducers.
The storage range covers cold warehouse transit; the operating range is the one to check for panel ambient near ovens or chillers. IP20 on the front with cover or box terminal; IP00 at the terminal itself. RoHS compliance dated 05/01/2012.