The LX4FF040 is a replacement contactor coil from the TeSys F range, designed for 48 V DC wide-range control circuits. It is the service-part coil that mates with TeSys F contactor frames — not a standalone contactor, but the interchangeable coil assembly you swap when the original coil fails or you need to change the control voltage on an existing contactor. Key operating parameters: closing time 30...40 ms, opening time 30...50 ms. Coil inrush power is 560 W at 68 °F (20 °C), dropping to 4.5 W holding power at the same temperature. The average resistance measures 2.86 Ohm inrush and 391 Ohm holding at 68 °F (20 °C). The coil carries an inductance of 27 H when closed. Control voltage limits at 158 °F (70 °C): operational range 0.7...1.25 Uc, drop-out range 0.2...0.45 Uc. The coil has no built-in suppressor module. If your application drives the coil from a PLC output or solid-state relay, you will need an external flyback diode or RC snubber across the coil terminals to protect the switching device from the inductive kickback. The 27 H inductance stores significant energy when energized.
What replaces it — the cross-reference question
The manufacturer does not list a direct drop-in successor order code for the LX4FF040 in the lifecycle record. Within the TeSys F family, the current-production coil range uses a different part-numbering scheme and may have different mounting or electrical characteristics. A pin-for-pin equivalent is not guaranteed without checking the specific contactor frame and coil mounting interface.