The Siemens SIRIUS 3RH2911-2XA40-0MA0-ZX95 is a front-mounted auxiliary switch block for 3RT2 power contactors and 3RH2 contactor relays. It provides four normally-open (NO) instantaneous contacts, each rated for a maximum of 10 A, with spring-loaded terminals for tool-free wiring.
Contact ratings and what they mean for your circuit
The headline 10 A maximum applies across the board, but the real-world switching capacity depends on the voltage you're working with. At 24 V, each NO contact is rated 6 A for the auxiliary contact path and 10 A at the rated-value column — the higher figure governs the contact's continuous current-carrying capability at that voltage. At 110 V, the rated value drops to 3 A; at 220 V, 1.2 A; at 440 V, 0.5 A; and at 600 V, 0.26 A. For AC-15 inductive loads at 690 V, the contact is rated 1 A. This derating curve means the part is sized for control-circuit switching across a wide voltage range, not for power-circuit duty.
Mounting and panel integration
Snap-on mounting onto the contactor or relay front — no tools needed. The block measures 36 mm wide, 41.5 mm high, and 47.7 mm deep. Spring-loaded terminals accept 2x (0.5 to 2.5 mm²) without core-end processing, or 2x (0.5 to 1.5 mm²) with ferrules. AWG equivalents are 2x (20 to 14) for auxiliary contacts. IP20 on the front means finger-safe but not sealed — keep it inside the enclosure, not on a washdown line.
Mechanical endurance and contact reliability
Rated for 10 million mechanical switching cycles typical. Contact reliability is specified as 1 faulty switching per 100 million operations at 17 V, 1 mA — a dry-circuit rating that matters for PLC-level signal integrity. Surge voltage resistance is 6 kV, with insulation voltage rated at 690 V AC for degree of pollution 3. Operating temperature range is -25 to +60 °C; storage range is -55 to +80 °C.