What it is and what it does
The Siemens 3RV1353-6LM10 is a SIRIUS molded-case circuit breaker (MCCB) designed specifically for starter combinations — meaning it's the protection device between the supply and a motor contactor, sized to handle both overload and short-circuit faults in one package. Rated for 20 A continuous current, it delivers 85 kA breaking capacity at 400 V AC — enough to safely clear a high-fault bolted short on a 400 V line without the arc flashing upstream to the main breaker. In AC-3 motor duty at 400 V, it's rated for 20 A operational current, which translates to roughly 7.5 kW for a standard 4-pole induction motor. That's the real-world sizing number for the buyer: the 20 A continuous rating covers the motor full-load current, and the magnetic short-circuit release handles the inrush.
Key ratings and what they mean for fit
The 85 kA breaking capacity at 400 V AC is the headline number for panel coordination. It means this MCCB can interrupt a fault current up to 85,000 A at 400 V without welding its contacts or rupturing the case — critical for panels fed from large transformers where the prospective short-circuit current is high. Breaking capacity drops to 10 kA at 690 V, so if you're running a 690 V motor circuit, the available fault current must be under that threshold or you need an upstream current-limiting device. Rated insulation voltage is 690 V, and surge voltage resistance is 8,000 V. The part is finger-safe (IP20 on the front, touch protection per the standard). Mounting position is any orientation, and it takes screw fixing with zero clearance required at the back or sides — meaning you can pack it tight against adjacent devices without derating for heat buildup, as long as ambient stays within -25 to +70 °C operating range.
Where it goes in the panel
This is a DIN-rail-mountable MCCB (screw fixing, but the footprint matches standard 90 mm width for a 3-pole device). Main circuit connections are screw-type terminals on the front side, with separate screw terminals for the auxiliary and control circuit. An auxiliary switch can be added as a product extension — useful for remote status feedback to a PLC. Dimensions: 130 mm high, 90 mm wide, 70 mm deep. Zero clearance at back and sides means no forced spacing between units on the rail.