What this auxiliary switch block does
The 3RH2911-2XA31-0MA0-ZW98 is a front-mounted auxiliary switch block for Siemens SIRIUS 3RT2 contactors and 3RH2 contactor relays, giving you 3 normally-open and 1 normally-closed additional contact paths — terminals labelled 53/54, 61/62, 73/74, and 83/84. Rated 10 A maximum, with AC-15 switching capacity at 690 V of 1 A — that's the rating that governs pilot-duty and control-circuit reliability, not the raw thermal current. The spring-loaded terminals accept 2x 0.5–1.5 mm² with ferrule or 2x 0.5–2.5 mm² without, so you land two conductors per clamp — handy for daisy-chaining control voltage across multiple auxiliaries in a row.
Current ratings across the voltage range
The thermal current rating is 10 A at 24 V, but the useful switching current drops as voltage rises: 6 A at 230 V, 3 A at 400 V, and 0.26 A at 600 V — the arc extinction limits the contact life at higher voltages, so size your control transformer and fuse accordingly. At 24 VDC the rated operational current is 6 A; at 110 VDC it drops to 1 A, and at 220 VDC to 0.3 A — DC switching is harder on contacts because there's no natural zero-crossing, so derate more aggressively than the AC figures suggest.
Mounting and panel fit
Snap-on mounting onto the contactor or contactor relay front — no tools needed, and the 36 mm width keeps the assembly within a single DIN-rail module footprint when stacked on the base unit. Overall dimensions are 36 mm wide, 47.7 mm deep, and 41.5 mm high — the depth is the critical dimension for enclosure clearance when the contactor is mounted against a gland plate or back panel.
Contact reliability and service life
Rated for 10 million mechanical switching cycles typical — the contacts themselves will last longer than the contactor's coil life in most cycling applications. Contact reliability is specified as 1 faulty switching per 100 million operations at 17 V, 1 mA — that matters when the auxiliary feeds a PLC input or safety relay that must see every transition, even at low signal levels.
Environmental and insulation ratings
IP20 on the front face — protected against finger contact but not against moisture ingress, so keep it inside a closed panel or enclosure. Rated insulation voltage 690 V AC at pollution degree 3, with surge voltage resistance of 6 kV — suitable for 400/480 V line-to-line control circuits with adequate clearance and creepage. Operating temperature range -25 to +60 °C, storage -55 to +80 °C — covers most indoor industrial environments without derating.