Square D S48891 Differential Ground Fault Interface Module

The Square D S48891 Modified Differential Ground Fault Interface Module (MDGF) is a DIN-rail mounted protection interface designed for Schneider Electric MasterPact NT/NW and ComPacT NS630b–NS3200 circuit breakers. It works within the MDGF protection scheme to monitor differential ground-fault signals and coordinate with dedicated MDGF sensors for each breaker in a panel or switchgear assembly. This 120 VAC device mounts on a standard 35 mm DIN rail and occupies a footprint of 4.17 in (106 mm) wide, 3.54 in (90 mm) high, and 2.28 in (58 mm) deep. Each circuit breaker in an MDGF-based installation requires an MDGF interface module (the S48891) to enable ground-fault sensing within Schneider Electric’s protection architecture. Commonly used in industrial power-distribution setups—such as large switchgear, data centers, and manufacturing facilities—the S48891 provides a dedicated MDGF interface for legacy and current MasterPact NT/NW breakers and NS-series configurations, ensuring consistent integration with MDGF sensors and preserving DIN-rail mounting convenience for modular panel design.