Motor Protection Circuit Breaker, 40 A, Class 10 — SIRIUS 3RV1031-4FA10-ZW97
The Siemens 3RV1031-4FA10-ZW97 is a SIRIUS motor protection circuit breaker rated for 40 A continuous current with a Class 10 trip characteristic, meaning it protects standard induction motors during start-up by allowing up to 10 seconds of locked-rotor current before tripping — a common spec for pump, fan, and conveyor drives on 400 V lines. Ground fault detection is not included — this is a straight thermal-magnetic overload and short-circuit protector, not a GFCI.
Rated short-circuit breaking capacity drops with system voltage: 100 kA at 240 V AC, 50 kA at 400 V AC, 10 kA at 500 V AC, and 4 kA at 690 V AC. At 400 V — the most common industrial distribution voltage — the 50 kA figure means this breaker can be applied on busways with up to 50 kA available fault current without needing a current-limiting backup fuse. The 690 V rating at 4 kA is marginal; if your panel feeds a 690 V motor and the SCCR at that bus exceeds 4 kA, you'll need a coordinated fuse ahead of it.
Main circuit terminals are screw-type box terminals accepting 2x solid conductors from 0.75 to 16 mm², or 2x stranded from 0.75 to 25 mm² plus a single 0.75 to 35 mm². For AWG, that's 2x 18 to 2 AWG solid or stranded, and a single up to 2 AWG. Fine-stranded wire with ferrule is accepted at 2x 0.75 to 16 mm² or a single 0.75 to 25 mm². The auxiliary and control circuit uses separate screw-type terminals. The product extension for an auxiliary switch is supported, so you can add a signal contact for PLC feedback or status indication without modifying the breaker body. Dimensions are 55 mm wide, 140 mm high, 149 mm deep — a standard three-pole SIRIUS frame that fits alongside contactors in a motor starter assembly.