What it is and what it does
The Siemens 3RH1140-1BF40 is a SIRIUS auxiliary contactor in size S00, carrying four normally-open instantaneous contacts with no delayed or lagging switching elements. The coil is rated 110 V DC with a pick-up threshold of 0.8 x rated voltage and a drop-out threshold of 1.1 x rated voltage; closing and holding power are both 3.2 W DC. The contact reliability spec calls for one incorrect switching operation per 100 million operations at 17 V, 1 mA, which is the low-energy test condition that governs PLC-level signal integrity.
Contact ratings by voltage — what they mean for your circuit
The contact ratings are given per IEC utilization category, not a single blanket current. At 24 V the contacts carry 10 A; at 110 V the rating drops to 1 A. At 230 V AC the rating is 6 A, at 400 V it is 3 A, at 500 V it is 2 A, and at 690 V it is 1 A. The 220 V DC rating is 0.27 A. These are the thermal continuous currents at the respective voltages — the actual switching capacity for inductive loads will be lower and should be verified against the load's inrush and time constant.
Mounting and integration into the panel
Fastening is by screw or snap-on mounting onto a DIN rail. The mounting position allows +/-180° rotation on a vertical surface and can be tilted forward and backward by +/-22.5°. The size S00 footprint measures 45 mm wide, 57.5 mm high, and 72 mm deep. The front face carries IP20 protection, meaning finger-safe but not sealed against moisture. Pollution degree 3 per IEC 60947-1 applies, so the contactor is rated for industrial environments with conductive pollution.
Environmental limits and mechanical endurance
Operating temperature range is -25 to +60 °C; storage and transport range is -55 to +80 °C. The contactor withstands shock at 10g for 5 ms and 5g for 10 ms. Mechanical life is 30 million operations typical. The rated surge voltage withstand is 6 kV, which aligns with overvoltage category III for 300 V AC systems.
Wiring and termination
The solid conductor termination accepts 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or 2x 4 mm². This covers the common control wiring gauges for auxiliary circuits. The reference code per IEC 81346-2 is K, consistent with contactor function in system documentation.