What it is and what it does
The Siemens SIRIUS 3RV2922-1CV0 is an undervoltage release — a control accessory that trips a motor circuit breaker when the control voltage drops below a set threshold. It's designed for use with 3RV2 series circuit breakers in sizes S00, S0, S2, and S3. The release is rated 400 V AC at 50 Hz, with a control supply frequency range of 50 to 60 Hz. It carries 2 normally-open (NO) leading auxiliary contacts, meaning the auxiliary contacts change state slightly ahead of the main trip action — useful for signaling or interlocking in a safety circuit. Snap-on mounting onto a 35 mm DIN rail keeps installation quick inside a panel. Screw-type terminals on the auxiliary and control circuit accept standard wiring — no special crimp tool needed. The break time is a maximum of 20 ms, fast enough to protect downstream equipment during a voltage sag.
Where it fits
This release snaps onto the front of a 3RV2 motor circuit breaker. The 19 mm width matches the breaker's modular pitch, so it doesn't eat extra DIN rail space. Depth is 68 mm, height 90 mm — check your enclosure depth if you're retrofitting into a shallow gland plate. Rated for pollution degree 3 (conductive pollution typical in industrial panels) and an operating temperature range of -20 to +60 °C. Storage range is -50 to +80 °C. The 690 V rated value covers most 400 V line-to-line systems with margin.