The Siemens 3RU1136-4DB0-ZW96 is a SIRIUS thermal overload relay in the Size S2 frame, designed to protect motors against overcurrent by tracking the thermal load and tripping a contactor when the motor draws excessive current over time. The relay mounts directly onto a contactor (contactor mounting) and accepts screw-type terminals for both the main power circuit and the auxiliary/control circuit, which is the conventional wiring method in most industrial control panels.
The main circuit terminals accept solid conductors from 2x (0.5... 1.5 mm²) up to 2x (0.75... 2.5 mm²), and stranded conductors from 2x (0.75... 25 mm²) up to 0.75... 35 mm² — that range covers most motor feeder cables from fractional-horsepower up to about 15 kW at 400 V, so you can land the motor leads without adapters. The auxiliary contacts are rated for switching at various control voltages: 1 A at 24 V, 3 A at 120 V, 2 A at 230 V, and 1 A at 400 V — these are the signal contacts that tell the PLC or starter circuit whether the relay has tripped, and the ratings confirm they handle standard 24 VDC and 120/230 VAC control circuits without derating. The front face carries an IP20 rating, meaning finger-safe against accidental contact but not sealed against dust or moisture — standard for inside a panel where the enclosure provides the environmental seal.
This relay mounts onto a contactor (contactor mounting) and fits the SIRIUS S2 platform, so it mates directly with the corresponding S2 contactor without additional brackets or wiring adapters — the power connections line up, and the auxiliary contacts snap into the control circuit. Clearance requirements are tight: 0 mm upwards, forwards, backwards, and downwards, with only 6 mm needed at the side — meaning it can be packed tightly against adjacent components on a DIN rail or panel, saving space in dense control cabinets.
It withstands 100 % relative humidity during operation, so condensation inside a non-sealed panel won't cause false trips — important for washdown areas or outdoor cabinets. The relay carries ATEX protection type DMT 98 ATEX G 001, meaning it is certified for use in potentially explosive gas atmospheres — this is a key spec for chemical, oil & gas, or grain-handling applications where a motor overload could ignite a surrounding atmosphere. Surge voltage resistance is rated at 6 kV, which aligns with IEC 60947-1 overvoltage category III for fixed installations — it will survive switching transients from contactors and drives without failing. Shock resistance is 8g for 10 ms, enough to handle vibration from nearby motors or conveyor systems without the relay's bimetal strip falsely tripping.