Coil for FF contactor frame, 300 V DC control
The LX4FF300 is a replacement coil for the FF-frame contactor in the TeSys range, rated for 300 V DC control circuits. It lands before the window or it doesn't go — the operating time is 30...40 ms closing and 30...50 ms opening, which is the critical path for sequencing logic in a panel rebuild. Coil technology is without built-in suppressor module, so the panel builder must add external flyback suppression (diode or RC snubber) across the coil terminals. The average resistance is 160.7 Ω inrush and 34910 Ω holding at 68 °F (20 °C), typical for a DC low-consumption design.
Control voltage limits and thermal range
Operational voltage window is 0.85...1.1 Uc at 131 °F (55 °C), meaning the coil holds in reliably from 255 V DC to 330 V DC. Drop-out threshold is 0.15...0.2 Uc (45...60 V DC), so the contactor releases cleanly on a sag without chattering. Ambient air temperature for operation is 23...131 °F (-5...55 °C).