The Siemens 3RV2902-2AV0 is a SIRIUS undervoltage release designed for use with 3RV2 motor circuit breakers in sizes S00, S0, S2, and S3. It trips the breaker when the control voltage drops below its dropout threshold, preventing automatic restart after a supply interruption — a standard requirement for machine safety circuits and process interlocks. Rated for 400 V AC at 50 Hz and 440 V AC at 60 Hz, the release operates across a 50–60 Hz supply frequency range. The control supply is AC only, so verify your panel's control transformer taps before specifying. Termination is via spring-loaded terminals for the auxiliary and control circuit, which speeds panel wiring and eliminates the need for torque checks on these connections. The unit snap-mounts directly onto the 3RV2 breaker — no additional DIN-rail space required.
Integration and environmental limits
The release measures 90 mm high by 18.5 mm wide by 68 mm deep — the 18.5 mm width matches a single modular unit, so it adds no extra panel width beyond the breaker footprint. Snap-on mounting means it clips onto the breaker's side without tools. This keeps the release coordinated with the breaker's internal clearances.
Substance compliance is documented: the RoHS exemption date is May 1, 2012, covering the standard EU RoHS scope. The reference code per EN 61346-2 is F (protective device).