The Siemens 3RV2902-2DB0 is a SIRIUS shunt release designed for remote tripping of 3RV2 motor circuit breakers in sizes S00, S0, S2, and S3. It accepts a 20-24 V AC control supply at 50/60 Hz and is rated for continuous duty at that voltage, with a separate 5-second ON period rating of 20-70 V AC or DC for applications needing a higher momentary pull-in voltage. Rated insulation voltage is 690 V at pollution degree 3, matching the 3RV2 breaker's main circuit isolation. The shunt release snaps onto the breaker's side via the standard DIN-rail mounting system — no additional panel space required beyond the breaker's own 19 mm width.
What the ratings mean for fit
The 20-24 V AC control supply is the continuous-duty range — the coil can be energized indefinitely at that voltage. The 5-second ON period rating of 20-70 V AC or DC is a separate, higher-voltage capability for applications where the trip signal is a short pulse, not a sustained hold. This dual rating is unusual for a shunt release and gives flexibility in control schemes: use the continuous range for standard undervoltage release circuits, or the short-pulse range for PLC-driven trip commands that clear after the breaker opens. The 690 V rated insulation at pollution degree 3 means the release is suitable for industrial environments with conductive dust or humidity, typical of motor control centers. The spring-loaded terminals accept solid or stranded wire without needing a screwdriver — a time-saver during panel assembly and a reliability gain against vibration loosening. Operating temperature range of -20 to +60 °C covers most indoor industrial enclosures; storage range of -50 to +80 °C is wider, covering transport and warehouse extremes. The 20 ms break time is the mechanical opening delay once the coil is energized — fast enough for most motor protection coordination schemes.