The Siemens 3RH2916-2DA11 is a lateral auxiliary switch block from the SIRIUS family, designed to snap onto the left side of 3RT2 contactors and 3RH2 contactor relays. It provides one normally-open (NO) and one normally-closed (NC) auxiliary contact, wired to terminals 41/42, 53/54 (NO) and 21/22, 33/34 (NC). Rated at 10 A maximum, the AC-15 switching capacity at 24 V is 10 A, dropping to 1 A at 690 V. This means it can handle pilot-duty loads like PLC inputs, relay coils, and signal lamps across a wide control voltage range — but the 690 V, 1 A figure is the limiting case for high-voltage control circuits.
Snap-on mounting to the contactor profile — no tools needed for installation, but removal requires a screwdriver to depress the latch. The 10 mm width adds minimal DIN-rail real estate. Spring-loaded terminals accept 2x (0.5 to 2.5 mm²) without ferrules, or 2x (0.5 to 1.5 mm²) with core-end processing. For AWG, that's 2x (20 to 14).
Contact reliability and service life
For a PLC input or safety relay monitoring a contactor auxiliary, this matters: the contacts are rated to switch logic-level signals without intermittent opens. Mechanical service life is 1 million switching cycles typical. That's the mechanism, not the electrical endurance — under load, expect fewer cycles, especially at higher currents or inductive loads.