What it is and what the key ratings mean
The Siemens 3RB2026-1SB0 is a SIRIUS solid-state overload relay — a CLASS 10E trip device that protects three-phase motor circuits from sustained overcurrent. CLASS 10E means it will trip within 10 seconds at 7.2× the thermal setting, which is the standard for standard-duty induction motors driving pumps, fans, and conveyors. The solid-state sensing eliminates the bimetal drift and ambient-temperature sensitivity of a thermal overload, so the trip curve stays repeatable across the operating range of -25 to +60 °C. It carries ATEX approval PTB 06 ATEX 3001 Ex II (2) GD, meaning it can be used in Zone 2 gas and Zone 22 dust hazardous areas when paired with an appropriate motor starter — a key spec for chemical, grain, or pharmaceutical lines where an arc from a failing thermal overload could ignite the atmosphere. The relay mounts directly onto a contactor (contactor mounting), saving DIN-rail space in a crowded panel. With a 45 mm width and 73 mm height, it fits the standard SIRIUS 3RT2 contactor footprint — no extra bracketry needed.
Integration notes
Wiring: main circuit terminals accept solid 0.5 to 4 mm² or 2× (0.5 to 2.5 mm²) — fine-stranded with ferrules also supported down to 0.5 mm². Auxiliary/control terminals use the same screw-type clamp, accepting 2× (0.5 to 2.5 mm²) solid or 2× (0.5 to 1.5 mm²) fine-stranded. The 6 kV surge voltage rating (IEC 61000-4-5) and 2 kV burst immunity (IEC 61000-4-4, severity 3) mean it holds up in industrial environments with motor drives and contactor switching nearby. Mounting position is any, so it fits vertical or horizontal panel layouts. Shock rated to 15g / 11 ms — fine for machine-mounted enclosures on punch presses or conveyors. The 0.02 W dissipation per pole keeps heat low inside a sealed cabinet.