Schneider Electric 9999ST1U 1P Circuit Breaker

Schneider Electric's 9999ST1U is a NEMA Type S motor starter and contactor with an integrated transient suppression module, designed to protect contacts from inductive spikes when switching motor loads. The unit covers NEMA sizes 00 through 2 and uses a 120 VAC, 60 Hz control coil, making it suitable for common 120 V control circuits in industrial panels. While part of Schneider Electric’s Square D line, it is not a standard circuit breaker; it is intended to control motor power in conjunction with a contactor and suppression module, delivering reliable start-up protection for loads such as conveyors, fans, pumps, and compressors. Key specifications include 120 VAC/60 Hz coil operation, NEMA sizes 00–2, and an integrated transient suppression module to absorb inductive energy during turn-off. For installation, select the appropriate size and wire the coil and auxiliary contacts per the 9999 Type S documentation to ensure proper coordination with your motor and control circuitry.