The Siemens SIRIUS 3UG4825-2CA40 is a residual current monitoring relay with digital setting, designed for three-phase supplies. It measures residual currents from 30 mA to 40 A, covering the range from sensitive ground-fault detection up to higher leakage levels typical on larger feeders. The relay operates on a 24 V DC control supply and provides a changeover output rated at 3 A at 250 V AC, suitable for driving a contactor coil or annunciator. The measuring circuit can detect currents as low as 10 mA, with a full-scale setting adjustable up to 43 A.
Mounting and Environment
Housed in a 22.5 mm wide enclosure, it snaps onto a standard 35 mm DIN rail or can be screw-mounted. IP20 protection on both the enclosure and terminals means it is intended for installation inside a control cabinet, not in a wet or dusty location. Rated for pollution degree 3, it is suitable for industrial environments with conductive or dry non-conductive pollution. Operating temperature range is -25 to +60 °C, with storage and transport limits from -40 to +85 °C.
Configuration and Diagnostics
The relay features an error memory function and supports an external reset, allowing it to be integrated into a manual or automatic reset scheme. A delayed switching function of 2 seconds is available to avoid nuisance tripping on inrush or transient leakage. The initial value is set at 0.85 of the full-scale value, and the full-scale value is 1.1, indicating the trip threshold is adjustable within a band around the nominal setting. The relay can be mounted in any position.