The Siemens 3RU2116-1AJ0 is a SIRIUS thermal overload relay in the S00 frame size, Trip Class 10, for standard-duty induction motor starts. It mounts directly onto a contactor (contactor mounting, any position) and uses a thermal bimetallic release that compensates for ambient temperature changes across -40 to +60 °C, so the trip point stays accurate whether the panel is in a heated plant or a cold warehouse. Rated insulation voltage is 690 V, with motor power ratings of 0.55 kW at 400 V and 0.75 kW at 500 V — sized for small three-phase motors in conveyor, fan, or pump duty.
Trip Class 10 is for motor starts that clear within 10 seconds. The auxiliary switch is integrated and carries the tripped signal — the Note field reads "for message 'Tripped'" — so it can be wired into a PLC input or a status lamp to indicate the relay has operated. The main current circuit uses ring cable lug connections (M3 screws), and the screwdriver spec is Pozidriv PZ2 with a 5–6 mm shaft diameter — no special tooling needed in the panel shop.
Substance prohibited as of 10/01/2009. MTTF under high-demand rate is 2,280 years.