Schneider Electric LA9D50978 Contactor Mechanical Interlock

Product Description

The SCHNEIDER ELECTRIC LA9D50978 is a mechanical interlock accessory designed for use with TeSys D series contactors. It physically links two contactors to prevent them from closing simultaneously, a critical safety function in reversing motor starters and other applications where simultaneous energization of two contactors would cause a fault or equipment damage. Licensed electricians and industrial maintenance technicians install this accessory during panel assembly or field retrofits. The LA9D50978 mounts directly to compatible contactor bodies without additional hardware, making it a straightforward addition to reversing or change-over starter configurations.

This interlock is rated for use in residential, commercial, and light industrial control panels wherever TeSys D contactors are deployed. It is suited for motor reversing starters, transfer switching arrangements, and any two-contactor wiring scheme that requires a hardwired mechanical lockout between the two devices. Compatible contactor families are listed in the Compatibility section below. The accessory installs at the contactor level, not the panel level, so it travels with the contactor assembly as a unit.

Key Features

• Mechanical interlock prevents simultaneous closure of two linked contactors
• Direct-mount design attaches to compatible TeSys D contactor bodies
• Supports reversing motor starter and change-over contactor configurations
• Single-piece accessory requiring no additional fasteners for installation
• Packaged as an individual unit (quantity 1 per package)

Compatibility

Designed for use with LC1D09 through LC1D38, LC1D80 AC, LC1D95 AC, LC1DT20 through LC1DT40, and TeSys D series contactors as specified by the manufacturer.

Installation Notes

Installation should be performed by a qualified electrician in accordance with NEC requirements and local codes. De-energize and lock out the panel before attaching or removing any contactor accessory. Verify that both contactors are fully de-energized and mechanically reset before engaging the interlock assembly. Do not force the interlock into position; proper alignment with compatible contactor bodies allows hand-pressure seating.