What this auxiliary switch block does
The Siemens 3RH2911-1GA04-ZW98 is a front-mounted auxiliary switch block with four normally-closed (NC) contacts, wired as separate current paths 51/52, 61/62, 71/72, and 81/82. It is designed specifically for use with SIRIUS contactor relays 3RH2140 and 3RH2440, per EN 50011, and is physically coded to prevent mismounting. Rated 10 A maximum, with AC-15 switching capacity varying by voltage: 10 A at 24 V, 6 A at 230 V, and 3 A at 400 V. For DC control circuits, the rated values drop to 0.5 A at 440 V and 0.26 A at 600 V — important when specifying for DC coil circuits or low-voltage interlock loops.
Mounting and panel fit
Snap-on mounting to DIN rail, 36 mm wide, 43.7 mm deep, 37.5 mm tall. The IP20 front protection means it is suitable for enclosed panels where the front face is not exposed to washdown or dust ingress. Screw-type terminals accept 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) conductors, or 2x (20 to 16) AWG. Insulation voltage rated 690 V AC at pollution degree 3, with surge voltage resistance of 6 kV — this covers standard 400 V line-to-line industrial panels with adequate clearance.
Lifecycle and sourcing
Mechanical service life is 10 million switching cycles typical, with contact reliability of 1 faulty switching per 100 million operations at 17 V, 1 mA — suitable for PLC input dry-contact circuits where low-level switching reliability matters.