The Siemens 3RV2021-1JA20-ZX95 is a SIRIUS motor-protection circuit breaker with Class 10 trip, phase failure detection, and overload and short-circuit protection. At 690 V the SCCR drops to 4 kA — still adequate for most 690 V motor circuits, but coordination with upstream protection needs checking at that voltage.
Depth is 97 mm from the rail face, so check the enclosure depth before committing the gland plate. Clearance requirements: 50 mm above and below, 30 mm to the sides, and zero forwards or backwards — so you can pack it against the back panel or a partition without derating. Main circuit terminals are spring-loaded, accepting up to 2× 10 mm² solid or stranded. That covers most motor feeds up to the 10 A rated current at 600 V. No torque driver needed for the spring clamps — just strip 8–10 mm and push in.
How it compares to the 3RV2021-1GA25
The 3RV2021-1GA25 is a sibling in the same SIRIUS frame — same 45 mm width, same DIN-rail mount, same Class 10 trip. The difference is in the current setting range and the SCCR curve. The -1GA25 is rated for a different motor FLA band; the -1JA20-ZX95 covers a specific range that may or may not overlap. If you're swapping one for the other, verify the thermal setting range matches your motor nameplate. The physical footprint is identical, so no panel rework needed.