Siemens SIRIUS 3RT1025-1AV00-0TA0 — Size S0 Power Contactor, 3 NO, 400 V 50 Hz
The Siemens SIRIUS 3RT1025-1AV00-0TA0 is a size S0 power contactor with three normally-open main contacts and zero normally-closed main contacts, rated for a main circuit of 400 V at 50 Hz. It mounts via screw fixing or snap-on onto a 35 mm standard mounting rail per DIN EN 50022, making it a direct fit for standard control panel enclosures. The front face carries an IP20 protection rating, while the terminals themselves are rated IP00 — a distinction that matters when the panel is open for commissioning or troubleshooting.
Motor ratings and duty cycles
For motor switching, this contactor is rated at 10 kW at 500 V and 11 kW at 690 V, covering the common European 400 V and 690 V industrial supply voltages. The AC-4 switching current at 400 V is 15.5 A — this is the rating that governs reversing or inching duty where the contactor makes and breaks motor current under load. The AC-2 rating at 400 V is 7.5 kW, applicable for slip-ring motor starting. For resistive loads (AC-12), the maximum operating current is 10 A.
Termination and wiring
Main current circuit connections use screw-type terminals. The solid conductor capacity accepts 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), and up to 2x (0.75 to 4 mm²). For stranded conductors, the range is 2x (1 to 2.5 mm²), 2x (2.5 to 6 mm²), and up to 2x 10 mm². AWG equivalents for main contacts are 2x (16 to 12), 2x (14 to 10), and 1x 8. These ranges cover the vast majority of motor feeder cables up to about 4 mm² per phase — no need for lug adapters on standard runs.
Coordination and protection
When used with type 2 coordination (no damage to the contactor under short-circuit), the required upstream fuse is gL/gG 25 A. For type 1 coordination (the contactor may need replacement after a fault), the fuse can be gL/gG 63 A. This distinction is critical for panel designers deciding whether the contactor must survive a fault without replacement.
Environmental and mounting
The contactor occupies a 45 mm width, 85 mm height, and 91 mm depth footprint. Side-by-side mounting is permitted, with a required 6 mm clearance at the side. Operating temperature range is -25 to +60 °C, and the maximum operating altitude is 2,000 m. Pollution degree 3 (conductive pollution or dry non-conductive pollution that becomes conductive due to condensation) applies, which is typical for industrial control panels not in clean-room environments.