The Siemens 3RV1021-4AA15 is a SIRIUS motor protection circuit breaker rated for 16 A continuous current, with a Class 10 trip characteristic and a breaking capacity of 50 kA at 400 V AC — enough to handle most 7.5 kW motor starts on a 400 V line without upstream coordination headaches.
The 45 mm wide body fits a standard DIN-rail footprint with zero clearance needed at the sides or rear — adjacent breakers can sit tight without derating concerns. Main circuit terminals accept solid conductors from 0.5 to 2.5 mm² (two per clamp) or stranded up to 6 mm²; auxiliary and control terminals handle 0.5 to 2.5 mm² solid or stranded. Mounting position is unrestricted, and the IP20 front protection keeps live parts behind the enclosure door — standard for panel installation.