The Siemens 3RU1146-4JB1-ZX95 is a SIRIUS thermal overload relay, Size S3, designed for motor protection in industrial control panels. Its CLASS 10 trip characteristic means it will trip within 10 seconds at 7.2× the set current, matching the thermal curve of standard induction motors during a locked-rotor event — a critical fit for protecting pump, fan, and conveyor drives against overload without nuisance tripping on startup inrush.
Key Ratings and What They Mean for Fit
The relay dissipates 5.7 W per pole, which matters for enclosure thermal budgeting — in a multi-motor panel, summing pole dissipation across several relays can push internal cabinet temperature above the -20 to +70 °C operating range if ventilation is marginal. Auxiliary contact ratings cover both standard 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 make/break capacities for the PLC digital input or contactor coil circuit the relay feeds — the 400 V 1 A rating confirms it can switch a 400 V contactor coil directly without an interposing relay. With type of coordination 2 requiring a 125 A gG fuse and type 1 requiring 200 A gG, the upstream short-circuit protection device is specified — a panel builder can size the branch circuit fuse without guesswork. The relay itself withstands 8 kV surge voltage, covering transient immunity for industrial mains.
Mounting and Integration
Stand-alone installation with a vertical mounting surface; the relay can be rotated ±135° or tilted ±45° front-to-back. Side clearance of 6 mm and zero clearance in other directions means it can be packed tightly against adjacent devices on the DIN rail or panel plate — useful when retrofitting into a crowded enclosure. Dimensions: 70 mm wide, 120 mm high, 140 mm deep. The 140 mm depth is the key constraint for shallow enclosures — verify the cabinet depth before committing the BOM line. Main circuit terminals accept stranded wire from 10 to 70 mm² or 2x (10 to 50 mm²); auxiliary and control circuit terminals accept 2x (0.5 to 1.5 mm²) solid or 2x (0.75 to 2.5 mm²) stranded. All terminals are screw-type — standard for panel wiring, no special tooling required.
Environmental and Compliance
Rated for 100 % relative humidity during operation and a storage/transport range of -55 to +80 °C — suitable for unheated warehouses or container shipping. Shock resistance of 8g for 10 ms covers normal transport and panel vibration. Protection class IP20 on the front — protected against finger contact but not water ingress; the relay is intended for a closed panel, not washdown areas. ATEX certification DMT 98 ATEX G 001 permits installation in potentially explosive gas atmospheres, provided the associated contactor and enclosure meet the system requirements. Substance prohibition date of 07/01/2006 aligns with RoHS compliance — the relay is free of the six original restricted substances as of that date.