What it is and what it does
The Siemens 3UG5825-1AA40 is a digital residual current monitoring relay designed for use with an external current transformer (type 3UL23). It covers an adjustment range from 0.03 A to 40 A, making it suitable for detecting ground faults or leakage currents in industrial AC circuits. The relay operates on a 24 V DC supply and provides both an ON delay and a tripping delay, each independently settable from 0.1 s to 999.9 s. Output is via a single changeover contact with screw terminals.