SIRIUS motor protection circuit breaker, 65 A frame
The Siemens 3RV2031-4JA10-ZW96 is a SIRIUS motor protection circuit breaker designed for the 65 A frame at 480 V, with a CLASS 10 trip characteristic that clears overloads fast enough to protect standard induction motors during start-up without nuisance tripping on normal inrush. Rated breaking capacity sits at 30 kA at 400 V, dropping to 4 kA at 500 V and 2 kA at 690 V — the 400 V figure is the one that governs most 400 V line-side fault scenarios in industrial panels. Motor power assignments are 18.5 kW at 230 V, 50 hp at 460/480 V, and 62 A at 600 V, so it covers a 50 hp motor on a 480 V North American supply or an 18.5 kW European-rated motor at 230 V.
Trip class and protection logic
CLASS 10 means the bimetal trip element opens within 10 seconds at 7.2× the thermal setting — fast enough to keep a motor winding below its thermal limit during a locked-rotor event, but not so fast that it trips on a normal start-up transient. Phase failure detection is built in, so a lost phase on the line side will trip the breaker rather than letting the motor single-phase and overheat. Ground fault detection is not included — if that's required, you'd add a separate ground-fault relay or choose a variant with that feature.
Mounting and panel fit
Mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 60715, in any orientation. Dimensions are 55 mm wide, 140 mm tall, 149 mm deep — the 55 mm width is a standard 3-module footprint on a DIN rail, so it occupies three 18 mm slots. Clearance requirements: 50 mm above and below, 10 mm to the side, zero forward or backward — tight panel layouts can use the zero forward/backward clearance to pack rows close together. Main circuit terminals accept 2×(1–35 mm²) or 1×(1–50 mm²) solid or stranded copper, with M6 screw terminals.