This is the replacement coil for LX1D4-series contactors — the part the line-side electrician swaps when the original coil burns out or the control voltage changes.
The 400 V AC 50 Hz control voltage is the coil's energizing supply — not the power circuit voltage. This coil pulls in the contactor when 400 V phase-to-phase at 50 Hz is applied across terminals A1-A2. If your panel runs 400 V at 60 Hz, confirm the coil's thermal rating; 50 Hz coils on 60 Hz see slightly higher impedance, which usually still picks but may hum or overheat on continuous duty. If your control transformer delivers 230 V or 24 V, this coil will not pick — it needs the full 400 V. As a TeSys-series coil, it mounts onto the contactor's magnet frame via the standard clip-and-plunger arrangement. No DIN-rail mounting — the coil is internal to the contactor assembly. Replacement means isolating the contactor, removing the arc chute and moving contacts, then sliding the old coil off the core and pressing the new one on.