Panel fit and switching capacity
The 3RH2122-4BG40: Mechanical endurance is 30,000,000 cycles typical, which suits high-cycle applications like conveyor interlocks or valve position feedback where the contactor outlasts the machine service interval.
Coil and switching characteristics
The DC magnet coil draws 4 W both closing and holding — no inrush spike, so the PLC output or relay driving it sees a steady load, and the 6 kV rated surge voltage resistance means it handles transient spikes from inductive loads without external suppression in most cases. Rated control supply voltage is 125 V with an initial value factor of 0.8 and full-scale factor of 1.1 — the coil will pick up at 100 V and hold at 137.5 V, so a sagging 120 V control bus still keeps it engaged.
It supports auxiliary switch extension, meaning you can add front-mounted switch blocks without changing the base contactor — useful if the control scheme evolves after the panel is built. RoHS compliance is dated 10/01/2009, so it meets the EU substance restrictions that apply to most industrial equipment shipped into Europe or following IEC standards.