The Siemens 3RV1421-4BA15 is a SIRIUS circuit breaker designed specifically for transformer protection, rated at 20 A continuous current with a CLASS 10 trip characteristic. It mounts on a 35 mm DIN rail per DIN EN 50022 using screw and snap-on fastening, occupying a 45 mm width in the panel.
Short-Circuit and Overload Ratings
The interrupting capacity is 100 kA at 240 V AC, 50 kA at 400 V AC, 10 kA at 500 V AC, and 4 kA at 690 V AC. These SCCR values determine where in the distribution this breaker can be applied — the 100 kA at 240 V suits high-fault utility feeds, while the 4 kA at 690 V covers the upper voltage range for transformer primary protection. The CLASS 10 trip curve means it clears overloads within 10 seconds at 600% of rated current, matching the inrush profile of transformers.
Main circuit terminals accept solid conductors 2x (0.5...1.5 mm²) and 2x (0.75...2.5 mm²), or stranded 2x (1...2.5 mm²) and 2x (2.5...6 mm²). AWG equivalents for the main contacts are 2x (14...10). Auxiliary and control circuits use screw-type terminals as well. The auxiliary switch is transverse design and the breaker supports product extension for auxiliary switches.
Operating temperature range is -20 to +60 °C, storage and transport -50 to +80 °C. Shock resistance is 25g for 11 ms. The product is RoHS compliant with a substance prohibition date of 01.05.2012. The lifecycle stage is current production.