Siemens SIRIUS 3RT2027-1BM40 — Size S0 Power Contactor, 24 VDC Coil
The Siemens SIRIUS 3RT2027-1BM40 is a Size S0 power contactor with a 24 VDC-rated magnet coil terminated at screw-type terminals. It mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 60715, fitting a standard panel enclosure. The 45 mm width and 107 mm depth keep it compact for multi-contactor assemblies. Rated switching frequencies vary by duty class: 1,000 operations/hour at AC-1 (resistive), 750/h at AC-2 and AC-3 (motor starting/running), and 250/h at AC-4 (plugging/inching). The AC-3e rating also supports 750/h. This means the contactor is sized for moderate-speed motor switching — typical for conveyor or pump duty — not high-cycle applications like servo indexing. DC switching capacity at 24 V is 10 A, dropping to 2 A at 48 V and 60 V, and 0.3 A at 220 V. The arcing time is 10 ms. For a panel-builder, the 24 V coil holds at nominal and drops out below 18 V — standard for 24 VDC control systems.
Mounting and Wiring
Mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward. Clearances: 10 mm upward, downward, and forward; 6 mm at the sides. Wire range for main contacts: solid or stranded 1–10 mm², or 2x (0.5–1.5 mm²) and 2x (0.75–2.5 mm²) for auxiliary contacts. The auxiliary switch is included on this variant. Operating temperature range is -25 to +60 °C; storage range is -55 to +80 °C. The contactor is rated for 10 million typical mechanical operations. For a line-down replacement, verify the existing panel has the 45 mm width slot and the 24 VDC control supply.