What it is and what it does
The Siemens 3RU1116-1GB0-ZW98 is a SIRIUS thermal overload relay — the part that sits between a contactor and the motor, watching for overcurrent and protecting the winding from sustained overloads. It's a 3-pole relay in the compact Size S00 frame, designed to mount directly onto a SIRIUS contactor (contactor mounting). Trip class is CLASS 10, which means it will trip within 10 seconds at 7.2× the set current — the standard choice for standard induction motors that don't need the ultra-fast trip of Class 5 or the longer ramp allowance of Class 20. For most conveyor, pump, and fan drives, this is the right call. The control circuit draws 1 A at 24 V, 3 A at 120 V, and 2 A at 230 V — so it's compatible with common control voltages across North American and European panels. Surge voltage resistance is rated at 6 kV, giving it decent margin for industrial environments with switching transients.
Where it goes and how it mounts
This relay mounts directly onto a SIRIUS contactor — no DIN rail bracket needed, no extra hardware. The mounting position is flexible: vertical mounting surface with ±135° rotation and ±45° tilt front-to-back, so it fits into tight panel layouts without fighting the wiring. Clearance requirements are minimal: 0 mm upwards, forwards, backwards, and downwards, with only 6 mm needed at the side. That means you can pack relays side-by-side without worrying about heat buildup from the 2.2 W per pole power loss — just keep the side gap. Wire terminations are screw-type for both main and auxiliary circuits. The main circuit accepts solid conductors: 2x (0.5...1.5 mm²) and 2x (0.75...2.5 mm²), plus AWG equivalents. Auxiliary contacts take 2x (20...16) and 2x (18...14) AWG. Finely stranded with core-end processing uses the same ranges.
Environmental and compliance
The front face carries IP20 protection — fine for inside a closed panel, not for washdown or outdoor exposure. Operating temperature range is -20 to +70 °C, storage and transport from -55 to +80 °C. Relative humidity up to 100 % is allowed, so condensation inside a non-heated enclosure won't necessarily cause issues. Shock resistance is rated at 8g for 10 ms — typical for industrial machinery vibration. It carries ATEX approval (DMT 98 ATEX G 001), so it's suitable for use in potentially explosive atmospheres when paired with the correct contactor and upstream protection.