Key ratings and what they mean for fit
The 3RH2911-1HA20-ZX95: Rated for a maximum of 10 A, but the real selection driver is the switching capacity at your control voltage. At 24 V the contacts handle 10 A (resistive) and 6 A (AC-15 inductive); at 230 V that drops to 6 A resistive and 1 A inductive. For 400 V control circuits the inductive rating is 3 A. The insulation voltage is 690 V AC at pollution degree 3, with a surge withstand of 6 kV — adequate for 400 V panels with proper clearance. Mechanical life is 10 million switching cycles typical, and contact reliability is rated at one faulty switching per 100 million operations at 17 V, 1 mA — a solid figure for PLC-level signal integrity in high-cycle applications.
Mounting and integration
Snap-on mounting to the contactor or relay front — no DIN rail footprint of its own. The block measures 36 mm wide by 37.5 mm high by 43.7 mm deep, so it adds about 44 mm to the device depth. Wiring accepts 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) with ferrule, or 2x (20 to 16) and 2x (18 to 14) AWG. IP20 on the front means it's for inside the panel only.