The Siemens 3RU2136-4AD0 is a SIRIUS thermal overload relay, Size S2, with a Trip Class 10 characteristic. It mounts directly to a contactor via the fastening method specified, making it a straightforward add-on for motor protection in a control panel. The relay is rated for an insulation voltage of 690 V and covers motor power ratings up to 7.5 kW at 400 V and 11 kW at 690 V, with corresponding full-load current settings reflected in the auxiliary contact ratings.
Trip Class 10 and Thermal Protection
Trip Class 10 means the relay will trip within 10 seconds at 7.2× the set current, which is the standard for protecting standard induction motors during start-up. The thermal overload release design compensates for ambient temperature changes between -40 °C and +60 °C, so the protection curve stays accurate whether the panel is in a conditioned space or a warm machine bay.
Auxiliary Contact Ratings and Integration
The integrated auxiliary switch provides status feedback — the note 'for message Tripped' indicates it signals a fault condition, not just the relay's on/off state. The contact ratings vary by voltage: 2 A at 24 V, 3 A at 120 V, 2 A at 230 V, and 1 A at 400 V. These are the make/break capacities for the signal circuit, so verify the PLC input card's sink current against these values. The relay mounts in any position and uses screw-type terminals for the main circuit, accepting 2x (0.5... 2.5 mm²) solid or stranded wire.