What it is and what it does
The Siemens 3RU2136-4FD1 is a SIRIUS thermal overload relay, Size S2, designed to protect motors against overcurrent and phase loss. It uses a thermal bimetallic release and is rated for a main circuit voltage up to 690 V at 50-60 Hz. The Trip Class 10 means it will trip within 10 seconds at a locked-rotor current of 7.2× the full-load setting — standard for general-purpose induction motors driving pumps, fans, or conveyors. The relay includes an integrated auxiliary switch that provides a separate signal contact for the control circuit, so a PLC or HMI can read the tripped state directly. The auxiliary contacts are rated for switching at various control voltages: 2 A at 24 V, 3 A at 120 V, 2 A at 230 V, and 1 A at 400 V. This covers common control voltages in industrial panels without needing an extra interface relay. Mounting position is any orientation, which simplifies panel layout. The screw terminals on the main current circuit accept 2×(0.5–2.5 mm²) solid or stranded wire — a Pozidriv PZ2 screwdriver tip is what you want on the van. Stand-alone installation means it doesn't need a separate base or adapter; it mounts directly to the contactor or panel.
Sourcing and lifecycle
Compliance documentation is available: the evidence notes a substance prohibitance date of 10/15/2014, aligning with RoHS and REACH requirements. The relay carries the SIRIUS brand, and standard Siemens documentation includes a CE declaration and UL/CSA file numbers — request these with your RFQ if your quality system needs them on file.
Dimensions and fit
The relay measures 55 mm wide, 105 mm tall, and 117 mm deep. The 117 mm depth is the critical dimension for enclosure depth — it fits standard 200 mm deep enclosures with room for wiring. The width (55 mm) matches the S2 contactor footprint, so it aligns directly with the 3RT2 series contactors without needing a separate adapter.