What this SIRIUS circuit breaker is and what it does
The Siemens 3RV2021-1JA10-0DA0 is a SIRIUS circuit breaker designed for system protection — meaning it protects downstream wiring and components from short circuits and overloads, not just a single motor. It carries a Trip Class 10 thermal overload characteristic, so it trips fast enough to protect standard induction motors during a stall or locked-rotor condition. The breaker is rated for a breaking capacity of 100 kA at 400 V AC, which is the figure that decides whether it can clear a fault without upstream fuses or breakers needing to intervene. At 690 V AC the breaking capacity drops to 6 kA, so coordination studies at higher voltages need attention. This is a Size S0 frame, which is the compact footprint in the SIRIUS range. It mounts via screw and snap-on onto a 35 mm DIN rail per DIN EN 60715, and the mounting position is any orientation — useful when panel space is tight. The 45 mm width means it occupies one standard 45 mm module slot on the rail.
Key ratings and what they mean for fit
The 100 kA breaking capacity at 400 V AC is the headline number — it means this breaker can safely interrupt a fault current up to 100,000 amps without welding its contacts or rupturing. That is high enough for most industrial main distribution panels; you would typically only need a higher SCCR for large transformer-fed switchgear. At 500 V AC the rating is 42 kA, and at 690 V AC it is 6 kA — so if your system runs at 690 V, verify the available fault current is under 6 kA. The motor power rating at 230 V AC is 2.2 kW — that is the maximum three-phase induction motor this breaker can protect in AC-3 duty (starting and stopping under load). The rated operational voltage for AC-3 goes up to 690 V, so it covers standard 400 V and 480 V motor circuits as well. The maximum switching rate is 15 operations per hour in AC-3, which is fine for a pump or conveyor that cycles a few times an hour, but not for a high-cycle application like a press or stamping machine.
Panel integration and wiring
The breaker snaps onto a 35 mm DIN rail per DIN EN 60715 and can be mounted in any position — no derating needed for horizontal or vertical orientation. The main circuit terminals are screw-type, accepting 2x 1 to 2.5 mm² or 2x 2.5 to 10 mm² solid or stranded wire. The screwdriver shaft needs a diameter of 5 to 6 mm, with a Pozidriv size 2 tip. The clearance requirements are 50 mm upward and downward, 30 mm to the side, and zero forward or backward — so it fits flush against the back panel.