SIRIUS power contactor for motor and resistive loads
The Siemens SIRIUS 3RT1325-1AU00 is a 4-pole power contactor in the size S0 frame, rated for 35 A at 40 °C ambient. Its 4 normally open main contacts handle motor loads up to 7.5 kW at 400 V AC (AC-2 duty), and it mounts via screw or snap-on onto a 35 mm DIN rail per EN 50022. The 35 A rating at 40 °C is the continuous current the main contacts carry in free air — derate for higher ambient or enclosed panels. The 7.5 kW AC-2 figure covers wound-rotor motor switching; for standard squirrel-cage motors (AC-3), the same contactor typically supports a similar power class, though the exact AC-3 rating is not listed here.
Termination and wiring
Main and auxiliary circuits use screw-type terminals. The main contacts accept solid or stranded conductors: 2x (1–2.5 mm²) or 2x (2.5–6 mm²), max 2x 10 mm². Auxiliary/control terminals take 2x (0.5–1.5 mm²) or 2x (0.75–2.5 mm²), max 2x (0.75–4 mm²). AWG equivalents: main 2x (20–16) or 2x (18–14), single 12 AWG. Side-by-side mounting is permitted with 6 mm spacing at the side. The enclosure carries IP20 on the front, IP00 at the terminals — the terminal area is not finger-safe until the panel cover is on.
Coil and control circuit
The coil operates at 50 Hz, with a voltage tolerance of 0.8 to 1.1 times the rated value. Switching capacity at 24 V is 10 A, derating to 2 A at 60 V, 1 A at 110 V, and 0.3 A at 220 V. The auxiliary contacts are rated for high reliability: one faulty switching per 100 million operations at 17 V, 1 mA.
Short-circuit coordination and environmental limits
For Type 2 coordination (no damage to contactor after a fault), use gL/gG fuses rated 25 A. For Type 1 coordination (contactor may need replacement), use 63 A fuses. The contactor is rated for pollution degree 3 (industrial environment with conductive pollution). Operating temperature range is -25 to +60 °C.