Square D DSII 850 EO DO 5000A LSG

The Square D DSII 850 EO DO 5000A LSG air circuit breaker is a heavy-duty low-voltage power circuit protection solution engineered for large industrial facilities, utility substations, and critical infrastructure applications. Manufactured by Square D, the DSII series is recognized for its rugged construction, high current capacity, and dependable long-term performance in demanding electrical environments.

With a continuous current rating of 5000 A and operating voltage up to 600 V AC, this breaker is designed to protect high-capacity three-phase distribution systems against overloads, short circuits, and ground faults. The integrated LSG solid-state trip unit provides long-time delay and short-time protection along with ground-fault detection, enabling accurate system coordination and improved selectivity with upstream and downstream protective devices. These protection functions help minimize equipment damage and reduce downtime during fault conditions.

The electrically operated (EO) mechanism allows remote closing and opening, supporting automation, control room operation, and integration into supervisory systems. The draw-out (DO) design enhances operational safety and maintenance efficiency by allowing the breaker to be racked into disconnect, test, or connected positions without removing primary connections. This feature significantly reduces maintenance time and improves system availability during servicing.

Built on the proven DSII metal-frame platform, the breaker offers excellent mechanical endurance and high short-time withstand capability for maximum reliability in high-fault-level systems. The DSII family supports advanced Digitrip RMS trip units with true RMS sensing, adjustable protection settings, and optional metering or communication features depending on configuration requirements. Designed for use in metal-enclosed switchgear assemblies, the series provides high interrupting ratings and compliance with major industry standards including ANSI, UL, CSA, and NEMA.

Overall, the Square D DSII 850 EO DO 5000A LSG air circuit breaker delivers exceptional current handling capability, advanced protection functionality, and robust mechanical design, making it an ideal solution for main incoming feeders, generator protection, and high-capacity power distribution systems where reliability and safety are critical.

Square D DSII 850 EO DO 5000A LSG Electrical Circuit Breaker, Electrically operated (EO) mechanism, Drawout (DO) cradle or racking system, Line and load terminals, LSG trip unit (Long-Time, Short-Time, Ground fault), Control wiring harness, Mounting hardware, User manual and installation guide, Calibration or test certificate (if applicable), Safety and compliance documentation, Manufacturer warranty card, Original Square D/Schneider Electric packaging