The Siemens 3RV2902-4AP0 is a SIRIUS undervoltage release — an accessory that drops the motor circuit breaker when control voltage falls below the dropout threshold. It's designed specifically for the 3RV2 family of motor circuit protectors in sizes S00, S0, S2, and S3. Control voltage is 230 V AC at 50 Hz, 240 V AC at 60 Hz, with a 50-60 Hz frequency range. Connection is via ring terminal lugs, not screw terminals — factor that into your panel wiring plan if you're swapping from a different release type.
Mounting and fit
Depth is 68 mm, height 90 mm. Rated for pollution degree 3 environments (industrial atmospheres with conductive or dry non-conductive pollution). Insulation voltage rated at 690 V AC at that pollution degree.
RoHS compliance date of 05/01/2012 is on file. Reference code per EN 61346-2 is F (protective device).
Performance and switching
Maximum break time is 20 ms — fast enough to clear a fault before the motor circuit breaker's own trip mechanism reaches its thermal limit. No leading or instantaneous auxiliary contacts on this variant (0 each), so it's a pure undervoltage function without status feedback. Short-circuit protection design assumes a fuse upstream — not a separate magnetic trip. The release itself is not a circuit breaker; it's a shunt-trip accessory that triggers the breaker's mechanical latch.