What it is and what the ratings mean for fit
The Siemens 3RU2116-0AB1 is a SIRIUS thermal overload relay, Size S00, designed for motor protection in control panels. Its Class 10 trip characteristic means it will open the circuit within 10 seconds at 7.2× the set current — fast enough to protect standard induction motors during a stall or locked-rotor event, without nuisance tripping on normal starting inrush. The relay is rated for a maximum operating voltage of 690 V, and its auxiliary contact block carries 2 A at 24 V, 3 A at 120 V, and 2 A at 230 V, giving you flexibility for signaling back to a PLC or contactor coil. The Size S00 form factor (89 mm high, 45 mm wide, 80 mm deep) is the smallest in the SIRIUS overload relay family, designed for direct mounting to S00 contactors or stand-alone installation on a DIN rail. The screw-type terminals accept 2x (0.5 to 2.5 mm²) solid or stranded wire, and the M3 main-contact screws are compatible with a Pozidriv PZ2 bit — a common panel-building tool.
Deployment context and environmental limits
This relay is temperature-compensated from -40 to +60 °C, so the trip curve stays consistent whether the panel is in a cold warehouse or a warm motor control center. It operates from -40 to +70 °C and survives storage and transport from -55 to +80 °C — a wide thermal envelope that covers most industrial environments. The mounting position is any orientation, which simplifies panel layout. The integrated auxiliary switch provides a normally-closed and normally-open contact for remote trip indication. The relay's note — "for message 'Tripped'" — confirms that the auxiliary contacts are wired to signal a tripped state, not just a contactor status. This is the contact you'd run back to a PLC digital input or a status light on the panel door.