What it is and where it fits
The Siemens 3RV2021-1JA10-ZW96 is a SIRIUS motor protection circuit breaker designed for motor protection duty. It snaps onto a 35 mm DIN rail per DIN EN 60715 and can also be screw-mounted — common in industrial control panels where a motor starter combo is built up with a contactor and overload relay downstream.
What the key ratings mean for a panel builder
The 100 kA interrupting capacity at 400 V AC (and 240 V AC) means this breaker can safely clear a fault up to 100,000 amps without blowing apart or welding its contacts shut. That's the kind of SCCR you need when the breaker sits close to a large transformer or a high-capacity bus — it lets you avoid adding a separate current-limiting fuse upstream. Class 10 trip means the bimetal releases within 10 seconds at 600% of the thermal setting. That's standard for protecting standard induction motors during a locked-rotor event — fast enough to prevent winding damage, but not so fast it nuisance-trips on a normal start. Phase failure detection is built in. If one phase drops out, the breaker trips — that's critical because a three-phase motor running on two phases will draw high current in the remaining windings and burn out quickly. Not all motor-protection breakers include this; some rely on the overload relay downstream. The 45 mm width and 97 mm depth mean it takes up a single DIN-module slot on the rail — standard for SIRIUS 3RV2 breakers in this frame size. The 97 mm height leaves room for the line and load terminals without crowding the next device.
Lifecycle and sourcing
The lifecycle stage is listed as current, meaning Siemens still actively manufactures this order code. No NRND or phase-out notice has been issued. For a BOM line or a panel build, this part is a standard catalog item — not a last-time-buy risk.
Mounting and wiring notes
Screw and snap-on mounting onto 35 mm DIN rail per DIN EN 60715. Mounting position any — no derating needed for horizontal or inverted rail orientation. The terminals accept 2x 1–2.5 mm² or 2x 2.5–10 mm² solid or stranded wire. Main contact screw terminals are M4. Clearance space: 50 mm upward and downward, 30 mm at the sides, 0 mm forward and backward (–). That's tighter than many breakers — you can pack devices close on the rail without needing extra breathing room behind or in front of the panel door.
Environmental and voltage range
Operating temperature –20 to +60 °C; storage and transport –50 to +80 °C. The rated voltage range is 20 to 690 V. Switching frequency at AC-3 duty is 15 operations per hour maximum — that's typical for a motor protection breaker used in start/stop cycles, not for high-speed jogging or reversing applications where a contactor handles the duty.