Coil specs for the panel builder
The LX9FK912 is a TeSys F specific contactor coil — the replacement or spare coil for a TeSys F contactor frame. It accepts a dual control voltage: 24 V DC and 27-29 V AC at 50/60 Hz, so one coil covers both a 24 V DC control bus and a 24 V AC supply (the AC range sits slightly higher due to the rectified waveform). Opening time is 60 ms, closing time 20 ms — the coil pulls in fast and drops out with a deliberate delay, which matters for coordinating with upstream protection or PLC scan cycles. Heat dissipation runs 15-18.3 W, so account for that in a dense DIN-rail enclosure; adjacent components need breathing room or forced convection. The coil has no built-in suppressor module. On a DC control circuit, you will want a free-wheeling diode or varistor across the coil terminals to clamp the inductive kickback — otherwise the back-EMF can couple noise into nearby electronics or damage the PLC output driving it.
Control voltage limits and drop-out behaviour
Operational voltage range is 0.85 to 1.1 Uc at 131 °F (55 °C) — meaning the coil holds in reliably down to about 20.4 V DC and up to 26.4 V DC. Drop-out occurs between 0.3 and 0.5 Uc, so the contactor releases cleanly when the control voltage falls below roughly 7-12 V DC. This gives a predictable undervoltage release characteristic for safety circuits. Hold-in power consumption is 29 W at 68 °F (20 °C), with an inrush of 470 W at the same temperature. The inrush spike is short — the inductance of the closed circuit is 0.22 H, which limits the steady-state current once the armature seats.