SIRIUS 3RU2126-1EJ0 — thermal overload relay, size S0, Class 10
The Siemens 3RU2126-1EJ0 is a SIRIUS thermal overload relay in the size S0 frame, designed for direct mounting onto a contactor (fastening method: contactor mounting). It uses a thermal bimetallic release to protect motors against overload and phase-loss conditions. This matches the majority of pump, fan, and conveyor applications in industrial panels.
Panel fit and mounting — size S0, 85 mm deep
The size S0 frame is the most common overload relay footprint in the SIRIUS family, fitting directly onto S0 contactors without additional adapter brackets. The main circuit connection uses ring cable lugs with M4 screws. The auxiliary switch is integrated, so no separate add-on block is needed for the trip/alarm signal.
Motor power ratings and auxiliary contact capacity
At 400 V AC-3e duty the relay is rated for 1.5 kW motor power; at 500 V it handles 2.2 kW; at 690 V it covers 3 kW. The maximum operating voltage is 690 V. These ratings let you match the relay to the motor nameplate without oversizing. These ratings cover the PLC input or alarm circuit draw in most control panels.
Compliance and substance restrictions
The 3RU2126-1EJ0 carries a substance prohibition date of 10/01/2009, which aligns with RoHS and REACH compliance milestones. The relay operates at 50/60 Hz and uses a Pozidriv PZ2 screwdriver tip for the terminal screws.