The LX4FK400: Coil technology is 'without built-in suppressor module' — no internal flyback diode or RC snubber. Add an external free-wheeling diode across the coil terminals to protect the DC control circuit from the inductive kick when the contactor drops out.
Control circuit voltage is 400 V DC, with operational limits of 0.85 to 1.1 Uc at 131 °F (55 °C). Dropout voltage sits at 0.2 to 0.35 Uc — the coil releases the armature when the control voltage falls below that range. Opening time is 45 to 60 ms; closing time is 50 to 60 ms. The maximum operating rate is 2400 cycles per hour at 131 °F (55 °C). Inrush power hits 1100 W at 68 °F (20 °C), then drops to 6 W holding. Average inrush resistance is 225 ohms; holding resistance jumps to 31,300 ohms. That large ratio is typical of DC economizer circuits — the coil pulls hard to close the contactor, then shifts to a low-power hold. The inductance of the closed circuit is 5270 H, which is high; the external free-wheeling diode must handle the stored energy when the coil de-energizes. Electrical life will be lower depending on the switched current and duty cycle.