Motor protection circuit breaker, 12.5 A, Class 10 — SIRIUS 3RV1021-1KA10-ZW95
The Siemens 3RV1021-1KA10-ZW95 is a SIRIUS motor protection circuit breaker rated for 12.5 A continuous current and 5.5 kW at 400 V AC, with a Class 10 trip characteristic. It snaps onto a 35 mm DIN rail (DIN EN 50022) and occupies 45 mm width, 97 mm height, and 96 mm depth — a compact footprint for a 3-pole device with screw-type terminals. The 100 kA breaking capacity at 400 V AC means this breaker clears faults up to that level without upstream fusing — useful for high-fault panels where you want to avoid cascading failures. At 690 V AC the breaking capacity drops to 6 kA, so verify the available fault current at your line voltage.
Protection and auxiliary features
Phase failure detection is built in, so the breaker trips on loss of a phase — critical for motor protection against single-phasing. Ground fault detection is not included. An auxiliary switch contact is available (listed as Yes), allowing remote status feedback to a PLC or indicator. Trip Class 10 means the breaker opens within 10 seconds at 7.2× rated current, matching standard motor starting profiles for pumps, fans, and compressors. The mechanical life is 100,000 operations typical for the main contacts.
Terminal capacity and wiring
Screw-type terminals on the main circuit accept solid or stranded conductors: 2x (1 … 2.5 mm²) and 2x (2.5 … 6 mm²), or AWG 14–10. Finely stranded with core-end processing uses the same cross-sections. This covers most panel wiring up to 6 mm² without needing ferrule adapters.
Environmental and mounting
Rated IP20 on the front — suitable for enclosed panels, not for washdown environments. Operating temperature range is -20 to +60 °C; storage and transport range is -50 to +80 °C. Shock resistance is 25g / 11 ms, so it holds up in transport and moderate vibration. Mounting position is any, giving flexibility in tight enclosures.