The Siemens 3RB2113-4PB0 is a SIRIUS solid-state overload relay — no bimetals, no heater elements, just a semiconductor-based trip that tracks true motor heating. The trip class is field-adjustable between CLASS 5E, 10E, 20E and 30E, so you can dial it in for standard motor start (10E) or a high-inertia load that needs the 30E curve to ride through the start without nuisance tripping. That means it tucks tight into a crowded panel where every millimeter counts. The IP20 front protection keeps fingers and tools out of the terminal area, but the body is open to the panel — standard for contactor-mounted overloads inside a cabinet.
Main circuit terminals are screw-type, accepting solid conductors from 0.5 to 4 mm² (or 2x 0.5 to 2.5 mm²). Finely stranded wire with ferrule takes 0.5 to 2.5 mm² (2x 0.5 to 1.5 mm²). AWG equivalents for the main contacts are 2x 18 to 14 AWG. Strip length and torque follow standard Siemens terminal practice — no special tooling needed.
EMC and surge robustness
The relay withstands burst transients per IEC 61000-4-4 at 2 kV on power ports and 1 kV on signal ports (severity level 3). That puts it well within the immunity requirements for industrial environments with contactors and drives switching nearby.