SIRIUS S0 power contactor for motor and resistive loads
The Siemens 3RT1025-1AL20-ZW96 is a SIRIUS S0-size power contactor rated for 10 A at AC-12 duty, meaning it handles resistive and control-circuit loads up to that current in 50/60 Hz systems. It mounts via screw or snap-on onto 35 mm DIN rail per EN 50022, fitting standard panel layouts. The S0 frame keeps the width to 45 mm, so it occupies a single DIN-rail module space. Depth is 91 mm, which matters for enclosure depth planning when the contactor sits behind a door or against a backplane.
Cold-environment operation and coil ratings
Operating temperature range is -25 to +60 °C during operation, so it runs cold and stays cold in freezer-adjacent panels or unheated enclosures. The coil holds at 24 V rated value drawing 10 A, with dropout below the typical threshold for 24 VDC control circuits. The contactor carries AC-2 and AC-4 ratings at 400 V: 7.5 kW for AC-2 duty (slip-ring motor starting) and 15.5 A for AC-4 duty (plugging/inching). For resistive loads at 400 V, the rated operating current is 3 A; at 690 V it supports 11 kW.
Coordination and terminal wiring
For Type 1 coordination (no damage to the contactor under short circuit), the required fuse is gL/gG 63 A. For Type 2 coordination (contactor remains operational after clearing the fault), the fuse drops to gL/gG 25 A. These values govern the upstream protection choice. Main circuit terminals accept solid or stranded conductors: 2x (0.5 to 1.5 mm²) and 2x (0.75 to 2.5 mm²), with a maximum of 2x (0.75 to 4 mm²). AWG equivalents are 2x (16 to 12) and 2x (14 to 10), plus 1x 8. The screw-type terminals are rated IP00 at the terminal point, while the front face carries IP20 finger protection.