What it is and what it does
The Siemens 3RH1140-1AP00 is a SIRIUS auxiliary contactor in frame size S00, carrying four normally-open instantaneous contacts. It is designed to extend the control-circuit switching capacity of a main contactor or to serve as a standalone signal relay in a panel. The coil pulls in at 24 V AC (50/60 Hz) with a tolerance band of 0.8...1.1 × rated voltage at 50 Hz and 0.85...1.1 at 60 Hz — so it holds reliably down to about 19.2 V at 50 Hz and 20.4 V at 60 Hz, and picks up cleanly at the lower end. Rated operational currents vary by voltage: 10 A at 24 V, 6 A at 230 V, 3 A at 400 V, 1 A at 690 V. That covers control-circuit switching across standard low-voltage supplies and into 690 V line-side signal isolation. Mechanical life is rated at 30 million operations; contact reliability is specified as one incorrect switching per 100 million operations at 17 V, 1 mA — a figure that matters for PLC-level dry circuits where oxide films on silver contacts can cause intermittent opens.
Mounting and integration
Mounts via screw or snap-on onto DIN rail. The 45 mm width (three module spaces) and 57.5 mm height fit standard S00 contactor footprints. The mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward — useful when the panel layout forces an unconventional orientation. The front face carries IP20 protection; the enclosure as a whole is pollution degree 3 rated, meaning it tolerates conductive dust in unsealed industrial environments. Terminals accept solid conductors: 2× (0.5...1.5 mm²), 2× (0.75...2.5 mm²), or 2× 4 mm². That covers most control-circuit wiring from 20 AWG up to 12 AWG. The auxiliary switch block is field-extendable (product extension auxiliary switch = Yes), so you can add more contacts on the same footprint without replacing the base unit.