The Siemens 3RH2911-1GA22-ZX95 is a SIRIUS auxiliary switch block that mounts on the front of 3RH2140 and 3RH2440 contactor relays, adding 2 normally-open and 2 normally-closed contact paths via screw terminals. It is physically coded to prevent mis-mounting on the wrong relay frame, so the install is unambiguous — the keying matches only the intended 3RH2 base units.
Contact ratings and what they mean for your circuit
The switch is rated for a maximum of 10 A, but the actual current it can break depends on the voltage and duty. At 24 V it handles 6 A; at 230 V it also carries 6 A, while at 400 V it drops to 3 A. For AC-15 inductive loads at 690 V the rating is 1 A. These are not derating curves to guess — the 6 A at 230 V tells you this block handles typical control-circuit loads (contactors, relays, solenoid valves) on a standard 230 V line without an extra interposing relay. The 1 A at 690 V AC-15 covers the higher-voltage switching found in some motor control centers.
Mounting and panel fit
Snap-on mounting onto the contactor relay — no tools needed for the attachment, but the screw terminals require a screwdriver for the wiring. The block is 36 mm wide, 37.5 mm tall, and 43.7 mm deep, so it adds about 44 mm to the relay depth. The screw terminals accept 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) with core-end processing, or the AWG equivalents 2x (20 to 16) and 2x (18 to 14). IP20 on the front means it is protected against finger contact but not against moisture — keep it inside a closed panel.