The ABB 1SDA038320R1 is an electronic time delay accessory designed for use with ABB molded case circuit breakers, particularly in the Tmax XT and Emax families. It provides a delayed trip / under‑voltage release function, allowing a breaker to stay closed for a short period before opening when the supply voltage drops or a specific timing event occurs. This module enhances the breaker’s protective coordination and can help prevent nuisance trips due to brief voltage disturbances.