What it is and what it does
The Siemens 3RV1021-0JA10-ZX95 is a SIRIUS motor protection circuit breaker designed for three-phase motor circuits up to 690 V. Its 1 A continuous current rating paired with a Class 10 trip characteristic means it protects motors against overload and short-circuit, tripping fast enough to prevent thermal damage during a stalled-rotor start — the Class 10 curve clears within 10 seconds at 7.2× rated current, which is the standard for standard-duty induction motors driving pumps, fans, and conveyors.
Breaking capacity and fault clearing
Rated breaking capacity hits 100 kA across the board — at 240 V, 400 V, 500 V, and 690 V AC. That means this breaker can safely interrupt a fault up to 100,000 A without welding contacts or cascading failure upstream, even on a high-capacity transformer secondary. For a 1 A motor protector, that is a very high interrupting rating, which simplifies coordination with upstream feeders.
Panel fit and mounting
Width is 45 mm, depth 96 mm, height 97 mm — a compact three-pole footprint. Mounts via screw or snap-on onto 35 mm DIN rail per EN 50022. Zero clearance needed at the back or sides, so it rows tightly on the rail without derating. Screw-type terminals on the main circuit accept 1…2.5 mm² solid or stranded (two conductors per clamp) or 2.5…6 mm² (two conductors). The 0 mm side clearance means you can pack breakers edge-to-edge in a multi-motor panel without worrying about heat buildup between units.
Environmental and mechanical endurance
Operating temperature range is -20 to +60 °C; storage and transport extend to -50 to +80 °C. Shock rated at 25 g for 11 ms, which covers most industrial vibration environments. Front face is IP20 — finger-safe but not sealed against moisture, so mount inside a panel rated for the ambient. Mechanical endurance is 100,000 operations on the main contacts, typical for a motor-starting duty cycle of 15 operations per hour at AC-3.
Protection features and auxiliary contacts
Phase failure detection is built in — the breaker trips on loss of any phase, preventing single-phasing damage to the motor. Ground fault detection is not included; that requires an external module. The breaker accepts auxiliary switches (sold separately) for remote status indication, but comes with zero factory-fitted auxiliary contacts.