The Siemens 3RV6021-4NA15 is a SIRIUS motor protection circuit breaker in the size S0 frame, rated for 28 A operational current at 690 V AC-3 with a Class 10 trip characteristic. It protects motor circuits against overload (thermal release) and short-circuit (magnetic release) in a single device, saving panel space over a separate contactor and overload relay combination. The 28 A rating at AC-3 duty means it handles motor starting currents up to that level — typical for a 15 kW (20 hp) motor at 400 V three-phase. The Class 10 trip curve allows the breaker to ride through normal start-up without nuisance tripping, yet still protect the motor from sustained overloads.
Mounting and integration
Mounts via screw fixing or snap-on onto 35 mm standard mounting rail per DIN EN 60715. The 45 mm width (size S0) fits a standard 45 mm slot on the rail; depth is 96 mm. Any mounting position is permitted, so it can be oriented to suit panel layout. Clearance: 50 mm above and below, 30 mm to the side, zero forward or backward — tight for dense panels but the zero forward clearance means no extra depth needed in front. Screw-type terminals on both main and auxiliary circuits accept 2x (0.5…1.5 mm²) solid or stranded, or 2x (0.75…2.5 mm²) — standard for panel wiring. Torque to 2…2.5 N·m on the main contacts.
Environmental and compliance
Operates from -20 to +60 °C, stores from -50 to +80 °C. Humidity tolerance 10…95 % RH. Shock rated at 25 g / 11 ms per IEC 60068-2-27. RoHS compliance date of 05/01/2012 (substance prohibition). Rated impulse withstand voltage 6 kV, surge voltage resistance 6 kV. Power dissipation 11 W typical at rated load.