What it is and what the ratings mean
The Siemens 3RU2136-4ED0 is a SIRIUS thermal overload relay, Size S2, designed to protect motors against overload and phase failure. Its CLASS 10 trip characteristic means it will trip within 10 seconds at 7.2× the set current — fast enough to protect standard induction motors during a locked-rotor event, without nuisance tripping on normal starting inrush. Rated voltage is 690 V, covering 400 V and 480 V motor circuits common in European and North American panels.
Where it fits and how it mounts
Mounts directly onto the contactor via the fastening method listed as contactor mounting — no separate DIN-rail bracket needed, which saves panel space. The Size S2 form factor (90 mm height, 55 mm width, 105 mm depth) pairs with Siemens S2 contactors like the 3RT1034 series. Screw-type terminals on the main current circuit accept 2× (0.5 to 2.5 mm²) solid or stranded wire; use a Pozidriv PZ 2 screwdriver tip with a 5 to 6 mm shaft diameter. Mounting position is any, so it fits tight enclosures without derating.
Auxiliary contact ratings and thermal limits
The integrated auxiliary switch provides signal feedback — the Note for message Tripped indicates this relay has a built-in trip-indicator contact. Its switching capacity varies by voltage: 2 A at 24 V, 3 A at 120 V, 2 A at 230 V, 1 A at 400 V, and 0.3 A at 60 V. These are the ratings for the auxiliary contact circuit, not the main power path. Power dissipation per pole is 4.6 W, which matters for thermal budgeting inside a sealed enclosure. Operating temperature range is -40 to +70 °C; storage and transport range is -55 to +80 °C. Temperature compensation is active from -40 to +60 °C, meaning the trip curve stays accurate across that span without manual adjustment.