Integrator's note on the 3RH1344-2BB40-ZW95
The Siemens SIRIUS 3RH1344-2BB40-ZW95 is a size S00 auxiliary contactor with a 24 VDC coil and four normally open (NO) instantaneous contacts. It's designed for control-circuit switching in motor starter assemblies or as a signal repeater in PLC output circuits. The DC coil draws 3.2 W both on pickup and hold, so the PLC output or relay driving it must be rated for that continuous load — no coil economizer is built in. Switching capacity is rated per contact across several voltage levels: 10 A at 24 V, 6 A at 230 V, 3 A at 400 V, 2 A at 500 V, and 1 A at 690 V. For DC control circuits, it also carries 1 A at 110 V and 0.27 A at 220 V. These are the thermal current ratings; for motor-circuit auxiliary duty, derate per the contactor's utilization category (typically AC-15 for solenoid loads). The contact reliability spec — one incorrect switching per 100 million operations at 17 V, 1 mA — tells you this part is suitable for dry-circuit logic signals (e.g., 24 VDC PLC inputs) without gold-plating concerns. Mechanical life is rated at 10 million operations typical.
Mounting and integration
Mounts via screw and snap-on onto a DIN rail. The size S00 footprint — 45 mm wide, 60 mm high, 114 mm deep — leaves room for a standard 4-pole contactor in a compact panel. Terminals accept 2x (0.25... 2.5 mm²) solid or stranded wire (2x 24... 14 AWG). The IP20 front protection means it's suitable for clean, dry control cabinets — not for washdown or outdoor exposure without an additional enclosure. Rated surge voltage resistance is 6 kV, and pollution degree 3 (conductive pollution or dry non-conductive pollution that becomes conductive due to condensation).