Industrial 609903-T001 Solid State Trip Unit

609903-T001 is an ABB solid-state trip unit (Type SS4) that forms part of the Power-Shield solid-state trip system used with I-T-E circuit breakers. This electronic trip unit, rated up to 1600 A, provides long-time, short-time, and instantaneous protection, with an optional ground-fault function when specified. It is designed to be installed as an integral protection module in ABB/ASEA Brown Boveri Power-Shield compatible breakers including I-T-E types K-600S through K-4000S, as well as K-DON variants (K-DON-600S, -800S, -1600S). The part number 609903-T001 (and the -N variant) is cataloged as an SS4 solid-state trip unit by ABB-affiliated suppliers; original manufacturing lineage traces to BBC Brown Boveri, ASEA Brown Boveri, now ABB. Some listings note that this model has been discontinued by the manufacturer, reflecting its vintage Power-Shield lineup.