The Siemens SIRIUS 3RH2911-1HA02-ZW96 is an auxiliary switch block that mounts on the front of 3RT2 contactors and 3RH2 contactor relays, adding two normally-closed (NC) circuits to the control scheme. It is rated for a maximum of 10 A and delivers 10 A at 24 V, with AC-15 switching capability of 1 A at 690 V — enough to handle most pilot-duty and signal-level loads in a motor control center.
What the ratings mean for fit
The 10 A maximum at 24 V covers the typical current draw of a PLC input module or a small contactor coil. The AC-15 rating of 1 A at 690 V is the key figure for switching solenoid loads in a 400–690 V panel — AC-15 is the utilization category for electromagnetic loads (contactors, relays), so this switch is rated for the inrush and inductive kick those loads produce. The contact reliability spec — one faulty switching per 100 million operations at 17 V, 1 mA — means it can handle dry-contact, low-energy signals from a sensor or PLC output without the oxide-film problems that plague unrated switches. The IP20 front protection means the operator-facing side is finger-safe but the terminals are not sealed against dust or moisture — this is standard for a panel-mounted auxiliary block inside a closed enclosure. The snap-on mounting lets it clip directly onto the front of the contactor or relay without tools, saving DIN-rail space and keeping the wiring within the same vertical column.
Integration note
The dimensions — 36 mm wide, 37.5 mm high, 43.7 mm deep — are compact enough to fit on the front of the contactor without protruding past the mounting base. The screw terminals accept 2x (0.5…1.5 mm²) or 2x (0.75…2.5 mm²) conductors, or the AWG equivalents 2x (20…16) and 2x (18…14). The surge voltage resistance of 6 kV and insulation voltage of 690 V at pollution degree 3 mean it is rated for the same isolation level as the contactor it mounts on — no derating needed in a standard 400 V panel.