Motor protection circuit breaker — SIRIUS 3RV2021-4AA25-ZW97
The Siemens SIRIUS 3RV2021-4AA25-ZW97 is a motor protection circuit breaker designed for motor loads, with Trip Class 10 and phase failure detection built in. It snaps onto 35 mm DIN rail (DIN EN 60715) and uses spring-loaded terminals for the main circuit — no screwdriver needed on the power side. Rated breaking capacity hits 25 kA at 400 V AC, which covers most industrial distribution panels without needing an upstream current-limiting fuse. The 45 mm width keeps it compact on the rail, and the 97 mm depth fits standard enclosure depths.
Breaking capacity and coordination
At 400 V, the 25 kA SCCR handles fault currents from a typical 630 kVA transformer secondary. For higher fault levels, the 690 V rating drops to 2 kA — that's the limit without series fusing. The 240 V rating of 100 kA is relevant for North American 277/480 V panels where the line-to-neutral fault can be high. The gL/gG fuse ratings at 400 V (63 A), 500 V (50 A), and 690 V (40 A) tell you the maximum backup fuse that preserves coordination. Stay within those for selective tripping downstream.
Mounting and wiring
Mounts in any position on 35 mm DIN rail per DIN EN 60715, screw or snap-on. The spring-loaded terminals accept 2x 0.5 to 2.5 mm² solid or stranded. Clearance: 50 mm above and below, 30 mm to the side, zero front/back — tight panel layouts work. Operating temperature range is -20 to +60 °C, storage -50 to +80 °C. Temperature compensation is active across the full operating range, so the thermal trip curve stays accurate in a warm enclosure.