The Schneider LA9FJ4F4F is a mechanical interlock from the TeSys F range, designed to physically prevent two or three contactors from closing simultaneously. It mounts in a 3-vertical configuration, linking the contactor operating mechanisms so that only one can be in the ON position at a time. This accessory is intended for use with specific TeSys F contactor frames: bottom position accepts LC1F115 through LC1F150 (3P or 4P) or CR1F150 (3P or 4P); middle position accepts the same LC1F115...LC1F150 or CR1F150 frames; top position accepts LC1F400 (2P, 3P, or 4P) or CR1F400 (3P or 4P). That means it coordinates reversing or two-speed motor starters where a simultaneous close would cause a phase-to-phase short.
Mounting position is 3 vertical — the interlock bar runs vertically between three contactors stacked in a column. This is a mechanical-only interlock; no electrical connections or wiring changes are needed. It clips onto the contactor bodies using the existing mounting slots, so panel layout stays the same as a standard three-contactor column.