Motor protection circuit breaker with integrated overload relay
The Siemens SIRIUS 3RV2131-4RA10 is a motor protection circuit breaker that combines short-circuit protection with an integrated overload relay function — one device, one footprint, no separate overload block to size and wire. Per the datasheet, it is designed specifically for motor protection with overload relay function, meaning it handles both the magnetic trip for fault currents and the thermal Class 10 overload curve for running protection. Breaking capacity is the headline number here: 30 kA at 400 V AC. That is the fault current it can safely interrupt without welding contacts or rupturing the housing. For a 400 V distribution panel with a transformer rating that keeps prospective fault current under 30 kA, this breaker coordinates without needing an upstream current-limiting fuse. At 690 V the rating drops to 2 kA, so verify the available fault current at the point of installation if running on a 690 V system. Phase failure detection is built in — if one phase drops out, the overload mechanism accelerates the trip, preventing single-phasing damage to the motor. No ground fault detection on this variant, so a separate ground-fault relay or RCD is needed if that is a code requirement.
Mounting and terminal details
Mounting is screw-fixed or snap-on onto 35 mm DIN rail per DIN EN 60715. The mounting position is any orientation, which simplifies panel layout. Clearance requirements: 50 mm upwards and downwards, 10 mm at the sides, zero forwards and backwards — so it can sit flush against a backplate or enclosure wall without derating. Main circuit terminals are M6 screw-type, accepting 2 x (1 to 35 mm²) or 1 x (1 to 50 mm²) solid or stranded copper. That covers most motor feeds up to the rated current range. The 75 mm width and 140 mm height mean it occupies roughly the same DIN footprint as a standard contactor of similar rating — plan for a 75 mm wide slot per device.