Motor-protective circuit breaker for 400 V panels
The Siemens 3RV2021-4NA40 is a SIRIUS motor-protective circuit breaker designed for motor protection, with a Class 10 trip characteristic that clears overloads fast enough to protect standard induction motors during locked-rotor starts. It snaps onto a 35 mm DIN rail per DIN EN 60715 or screws into the panel — the 45 mm width fits standard feeder slots in a motor control center. Breaking capacity hits 25 kA at 400 V, so it safely interrupts faults up to that level without cascading upstream — sized for industrial distribution where the available fault current is known. At 480 V the rated current is 28 A; at 500 V the breaking capacity drops to 5 kA, and at 690 V to 2 kA. That derating curve matters when you're specifying for a 480 V line or a 690 V drive input.
Mounting and integration
Mounts in any position — screw or snap-on onto 35 mm DIN rail per DIN EN 60715. The 97 mm depth is the dimension that governs enclosure depth; 45 mm width means it occupies one standard 45 mm slot in a motor control center. Clearance: 50 mm above and below, 30 mm to the side, 0 mm forward or backward — so you can butt it against the backplane or a busbar without extra spacing. Main-circuit connection uses ring cable lugs on M4 screws — no spring-cage option here. Phase-failure detection is built in; ground-fault detection is not, so if you need GF protection you'll add an external module or a separate ground-fault relay.
Lifecycle and sourcing
The lifecycle stage is listed as current. No EOL notice or successor has been issued for this order code.