The Siemens 3RU1116-1FB0-ZX95 is a SIRIUS thermal overload relay, size S00, with CLASS 10 trip. It mounts directly to a contactor and uses bimetallic strips to model motor heating, tripping the auxiliary contact when the thermal load exceeds the CLASS 10 curve. The IP20 front protection keeps live parts behind the panel door, standard for enclosed control panels.
CLASS 10 trip class is the critical selection parameter: it matches the heating time constant of standard general-purpose induction motors. If your motor manufacturer specifies a CLASS 10 overload, this relay provides the correct thermal protection without nuisance tripping on startup. The S00 frame size (45 mm wide, 87 mm tall, 78 mm deep) fits the Siemens S00 contactor footprint — it clips onto the contactor without additional DIN-rail space. The auxiliary contact ratings cover common control voltages: 1 A at 24 V, 3 A at 120 V, 2 A at 230 V, and 1 A at 400 V, so it can directly switch a PLC input or a contactor coil across a range of control supplies.
Wiring and installation constraints
The main circuit accepts solid conductors: 2× (0.5 to 1.5 mm²) or 2× (0.75 to 2.5 mm²), with AWG equivalents 2× (20 to 16) and 2× (18 to 14). Auxiliary contacts take 2× (20 to 16) and 2× (18 to 14) AWG. That zero-clearance top and bottom means you can stack contactor-overload assemblies without extra spacing — useful for high-density motor control centers.