The Siemens 3RT2327-2BM40 is a SIRIUS contactor in size S0, designed for DC coil operation with spring-type terminals. The DC coil means this contactor is suited for applications where the control voltage is DC, common in battery-backed systems or PLC-driven outputs. The spring-type terminals on the magnet coil reduce wiring time and eliminate the risk of screw-terminal loosening under vibration.
The main contact current ratings are given per voltage for DC switching: 10 A at 24 V, 6 A at 60 V, 3 A at 400 V, and 1 A at 690 V. These are the DC-1 or DC-3 type loads; the 10 A at 24 V rating is the one that governs most control-circuit applications, while the 3 A at 400 V matters for small DC motor or brake loads in a 400 VDC bus. The contactor carries an auxiliary switch, which is critical for feedback to a PLC or for interlocking in a reversing starter.
The contactor measures 60 mm wide, 102 mm high, and 107 mm deep.
Wiring and terminal capacity
The spring-type terminals accept solid conductors from 2x (0.5 to 2.5 mm²) and stranded conductors from 1 to 10 mm². This range covers most control wiring up to 10 mm² for power circuits, and the dual solid termination allows daisy-chaining of control wires without a separate terminal block.