The Siemens 3RT1045-3AF08-0PA3-ZX95 is a SIRIUS S3 power contactor rated for 37 kW in AC-3 duty at 400 V and 66 A in AC-4 at 400 V — the AC-4 figure governs reversing or inching applications where the contactor breaks full motor current at each transition.
Side-by-side mounting is permitted, so the contactor nests against adjacent SIRIUS devices without a mandatory air gap — useful when packing a multi-contactor motor starter group into a tight panel. Accepts 2x (0.25 to 2.5 mm²) solid or 2x (10 to 50 mm²) stranded — the stranded range covers the full motor feeder cross-section for a 37 kW load without needing an adapter lug. Dimensions: 146 mm high, 100 mm wide, 139 mm deep. The 139 mm depth includes the terminal projection; verify clearance to the gland plate or enclosure door in retrofit panels.
Duty-cycle and thermal limits
Rated for 50/60 Hz operation with a voltage tolerance of 0.8 to 1.1 times the nominal at 50 Hz. Maximum switching rates: 1 000 operations per hour in AC-3, 900 in AC-1, 400 in AC-2, and 300 in AC-4 — the AC-4 rate is the constraint for jogging or plugging cycles.