What it is and what it does
The Siemens SIRIUS 3RV1902-1AF0 is an undervoltage release designed for use with SIRIUS 3RV motor circuit breakers in sizes S00, S0, S2, and S3. Its job is to trip the breaker when the control supply voltage drops below a set threshold, protecting the motor and downstream equipment from damage during a brownout or power loss. The coil is rated for 110 V AC at 50 Hz and 120 V AC at 60 Hz, so verify your line frequency matches the tap — it is not a universal-voltage coil.
Lifecycle and sourcing reality
This part is explicitly marked as a phased-out product. The official Siemens successor is the SIRIUS 3RV2902-1AF0, which is the preferred replacement type. If you are filling a BOM line or a panel that was specified around the 3RV1902-1AF0, the 3RV2902-1AF0 is the drop-in cross-reference to target. For the original order code, we source it to order against an RFQ through independent distribution channels; availability and current pricing are confirmed at quote time.
Mounting and integration
Snap-on mounting onto a 35 mm DIN rail per DIN EN 60715. The 18.5 mm width means it occupies a single 18 mm module slot in the enclosure — a tight fit for a crowded panel. Depth is 68 mm, height 90 mm. It is designed for use with the SIRIUS 3RV motor circuit breaker family; the release mechanically couples to the breaker's trip mechanism, so no auxiliary contacts are needed for the trip function itself (the release has zero NO, NC, or CO contacts).
Environmental and electrical ratings
Rated insulation voltage is 690 V AC with degree of pollution 3, which is the standard industrial environment (conductive pollution or dry non-conductive that becomes conductive due to condensation). Operating temperature range is -20 to +60 °C; storage range is -50 to +80 °C. The control supply voltage is AC only — no DC variant here. The reference code per EN 61346-2 is F, classifying it as a protective device.