The Siemens 3RB2026-2SB0 is a SIRIUS solid-state overload relay — a CLASS 20E device that mounts directly onto a contactor, not on a DIN rail. It protects motors against overload and phase failure by monitoring current through the main circuit and tripping via the contactor coil circuit. The ATEX certification (PTB 06 ATEX 3001 Ex II (2) GD) means it can be used in potentially explosive atmospheres as a associated apparatus, provided the contactor and enclosure meet the zone requirements.
CLASS 20E trip class means the relay allows up to 20 seconds of locked-rotor current before tripping — a standard match for general-purpose induction motors that need a brief starting current window without nuisance trips. Mounting type is contactor mounting — this relay clips onto the front of a compatible SIRIUS contactor, saving DIN-rail space and reducing wiring between the overload and the contactor coil. The auxiliary contact ratings cover a wide control-voltage range: 2 A at 24 V, 4 A at 120 V, 3 A at 230 V — enough to switch most PLC inputs or contactor coils directly. The 0.05 W power dissipation in hot operating state means negligible heat contribution inside the enclosure. Shock resistance of 15g / 11 ms means it survives shipping and moderate vibration on a machine. EMC immunity includes 2 kV burst on power ports and 1 kV on signal ports (severity level 3 per IEC 61000-4-4), plus 6 kV surge voltage resistance — adequate for industrial power-distribution panels without additional suppression.
Wiring and installation details
Main circuit terminals accept 0.5 to 4 mm² solid or 2x 0.5 to 2.5 mm². AWG equivalent is 2x 14 to 10. Mounting position is any, so the relay can be installed horizontally or vertically without derating — useful when panel layout forces a non-standard orientation. Clearance distances: 0 mm upwards, forwards, backwards, and downwards — the relay can be stacked flush against adjacent components. Side clearance is 6 mm minimum.