What it is and where it fits
The Siemens 3RB2036-1UX1 is a SIRIUS solid-state overload relay — a CLASS 10E trip device for three-phase motor protection. It mounts as a stand-alone unit in any position, with zero clearance required upwards, forwards, backwards, and downwards, and only 6 mm to the side, so it packs tightly into a control panel without derating for spacing.
Key ratings and what they mean for your BOM
The CLASS 10E trip curve means the relay will trip within 10 seconds at 7.2× the current setting — standard for protecting standard induction motors during start-up without nuisance tripping on normal acceleration. The main current circuit uses straight-through transformers, so the motor leads pass directly through the relay's integral current transformers, eliminating the need for external CTs. Switching capacity is rated per the auxiliary contact: 2 A at 24 V, 4 A at 120 V, and 3 A at 230 V — these are the maximum currents the built-in NC contact (one normally closed auxiliary contact) can break. The contact is rated for AC and DC control circuits, with derated values at higher DC voltages: 0.55 A at 60 V, 0.3 A at 125 V, and 0.11 A at 220 V. Environmental robustness: operates from -25 to +60 °C, stores and ships from -40 to +80 °C, and withstands 100 % relative humidity. Shock resistance is 15g for 11 ms, and surge voltage withstand is 6 kV. EMC immunity meets IEC 61000-4-4 severity level 3: 2 kV on power ports, 1 kV on signal ports.
Termination and wiring
Auxiliary and control circuits terminate on spring-loaded terminals accepting 2x (0.25... 1.5 mm²) solid or finely stranded with ferrule, or 2x (24... 16 AWG). The spring-cage design speeds panel wiring — no screw torque to verify, just strip to 8 mm and insert.
Compliance and approvals
ATEX certified: PTB 06 ATEX 3001 Ex II (2) GD, suitable for installation in Zone 2 gas and Zone 22 dust atmospheres when paired with an appropriate motor. RoHS compliance is indicated by the substance prohibition date of 07/01/2006. The IEC 81346-2 reference code is F (protective device).