What it is and where it fits
The Siemens SIRIUS 3RH2911-2HA20-ZX95 is a front-mounted auxiliary switch block designed specifically for 3RT2 power contactors and 3RH2 contactor relays. It adds two normally-open (NO) instantaneous contacts to the front of the device, expanding the signaling or interlocking capability of the contactor assembly. It snaps onto a DIN rail via the host contactor's mounting base, so no additional panel space or drilling is required — it simply clips onto the front of the 3RT2 or 3RH2 device.
Key ratings and what they mean for your circuit
The contacts are rated for a maximum of 10 A, but the real-world switching capacity depends on voltage and load type. At 24 V AC-15 (the standard for contactor coil control circuits), it switches 6 A; at 230 V AC-15, also 6 A; at 400 V AC-15, 3 A. For DC loads, the ratings drop significantly — 0.3 A at 220 V DC, for instance — reflecting the arc-quenching challenge of DC switching. The mechanical service life is rated at 10 million switching cycles typical, which outlasts most contactor main contacts in normal PLC or motor-starter duty. The contact reliability specification — 1 faulty switching per 100 million operations at 17 V, 1 mA — confirms it handles dry (low-energy) logic signals without needing gold-plated contacts.
Wiring and integration details
Termination is via spring-loaded terminals — no screwdriver needed for the connection, just strip the wire and push it in. Accepts 2x (0.5 to 1.5 mm²) with ferrule, or 2x (0.5 to 2.5 mm²) without core-end processing. AWG equivalent is 2x (20 to 14). The block dimensions are 36 mm wide × 47.7 mm deep × 41.5 mm high. IP20 on the front means it's protected against finger contact but not moisture — suitable for enclosed control panels only, not washdown zones. Rated insulation voltage is 690 V AC at pollution degree 3, with a surge voltage withstand of 6 kV. Operating temperature range is -25 to +60 °C; storage range is -55 to +80 °C.
Sourcing and lifecycle reality
The 3RH2911-2HA20-ZX95 is a standard catalog item for Siemens SIRIUS, so it can be specified into new BOMs with confidence. For urgent line-down needs, it is sourced to order against an RFQ through normal supply routes.