The LA9FJ4F is a TeSys F mechanical interlock accessory from Schneider Electric, designed to prevent simultaneous closure of two contactors in a reversing or changeover configuration. It uses a mechanical interlocking type, meaning a physical linkage between the contactor armatures ensures only one can be in the closed position at any time — no electrical interlock logic required.
Which contactors it fits
This interlock mounts in a 2-vertical position and is compatible with bottom-mounted LC1F115 through LC1F150 3P or 4P contactors (and their CR1F150 reversing counterparts), as well as top-mounted LC1F400 2P, 3P, or 4P contactors (and CR1F400). The mechanical interlock physically couples the two contactor armatures, so the mounting orientation and contactor frame size must match the LA9FJ4F's intended pairing — verify the contactor catalog numbers against the interlock's compatibility list before specifying.