The Siemens 3RT1024-1BB40-ZX95 is a SIRIUS S0 power contactor with a 24 VDC coil, screw-type terminals for the main current circuit, and a rated operational power of 7.5 kW at 500 V and 690 V. It mounts via screw and snap-on onto a 35 mm DIN rail per DIN EN 50022, with a 45 mm width and 101 mm depth that fits standard panel layouts. The front face carries an IP20 rating; the terminals themselves are IP00, so panel builders should account for clearance around the wiring compartment.
Ratings and what they mean for fit
The AC-4 rating of 12.5 A at 400 V governs the contactor's ability to switch motor loads under reversing or inching duty — the most demanding thermal cycle for a contactor. For AC-2 duty (slip-ring motors), the same voltage yields 5.5 kW. The magnet coil draws 5.4 W during both closing and holding, a steady-state DC consumption that simplifies power-supply budgeting in a 24 VDC control circuit. The auxiliary contact block carries 10 A at AC-12 (resistive loads) and derates to 6 A at 230 V, 3 A at 400 V, and 2 A at 60 V DC. For DC switching at 24 V the rating is 10 A. The mechanical endurance is listed at 10,000,000 typical operations — a figure that assumes the contactor is not switching its rated load; electrical endurance under full AC-3 load will be lower and should be verified against the application's duty cycle.
Wiring and coordination
Screw terminals accept solid conductors from 2x (0.5 to 1.5 mm²) up to a maximum of 2x (0.75 to 4 mm²), and stranded conductors from 2x (1 to 2.5 mm²) up to 2x 10 mm² maximum. For type 2 coordination (no-weld requirement), the recommended backup fuse is gL/gG 25 A; for type 1 coordination (allowable weld but no fire risk), the fuse rating rises to 63 A. Pollution degree 3 means the contactor is rated for industrial environments with conductive contamination — no additional conformal coating required for most panel conditions.