Motor Protection Circuit Breaker for the Panel Rail
The Siemens 3RV1021-1DA15-ZW97 is a SIRIUS motor protection circuit breaker rated for 3.2 A continuous current, designed to protect motors up to 1.1 kW at 400 V AC. Its Trip Class 10 characteristic means it trips within 10 seconds at 7.2× rated current, matching the thermal curve of standard induction motors during a locked-rotor start. Phase failure detection is built in, so a lost phase on the line side will trip the breaker before the motor single-phases to failure. The breaker snaps onto a 35 mm DIN rail per DIN EN 50022 and can be mounted in any position, which simplifies layout in a crowded panel. Screw terminals on both the main and auxiliary circuits accept solid conductors from 0.5 mm² up to 2.5 mm² (two per clamp) and stranded up to 6 mm², covering the typical motor branch wiring range. The front face carries IP20 protection, so accidental finger contact is blocked during commissioning. Breaking capacity is 100 kA at 400 V AC, meaning it can safely interrupt a fault current up to that level without welding contacts or cascading failure upstream. At 690 V the rating drops to 8 kA, so verify the available fault current at the point of installation if the system runs at higher voltage. Power dissipation at rated current is 7.25 W — a factor to include in the panel thermal budget when grouping several breakers.
Integration Notes for the Panel Builder
Dimensions are 45 mm wide, 97 mm high, and 96 mm deep — a standard 45 mm module width that occupies one position on the DIN rail. Zero clearance is required at the back and sides, so the breaker can be installed directly against adjacent devices without derating for air circulation. The auxiliary switch is a transverse design and is field-addable, allowing remote status indication without an extra module. Operating temperature range is -20 to +60 °C; storage and transport range is -50 to +80 °C. Shock resistance is rated at 25 g for 11 ms, which covers the vibration profile of most industrial machinery and conveyor systems. The maximum operating frequency in AC-3 duty is 15 switching cycles per hour — adequate for motor start/stop applications but not for high-cycling loads like rapid reversing drives.