Motor protection circuit breaker for Class 20 overloads
The Siemens 3RV2031-4SB10 is a SIRIUS motor protection circuit breaker designed for Class 20 overload protection, meaning it trips within 20 seconds at 7.2× the thermal setting — standard for general-purpose motors driving pumps, fans, and light conveyors where moderate start-up times are acceptable. At 690 V the interrupting rating drops to 3 kA — still adequate for 690 V motor circuits in European or mining installations where the transformer impedance limits fault current. The 55 mm width fits standard 18 mm-module spacing — three modules wide, which is typical for this frame size. Terminal capacity accepts up to 2×25 mm² or 1×35 mm² solid/stranded, M6 ring terminals for the main contacts.
Integration notes
Clearance: 50 mm above and below, 10 mm to the side — no forced-air spacing required at rated currents. Maximum switching frequency is 15 operations per hour under AC-3 duty — fine for motor start/stop cycles on a conveyor or compressor, but not for high-cycle jogging applications. Trip Class 20 means the overload curve is set for motors that reach full-load current within 10-20 seconds; for high-inertia loads requiring longer start times, a Class 30 or electronic overload would be needed.