The Siemens 3RU1146-4MB0-ZX95 is a SIRIUS-brand thermal overload relay, Size S3, designed for contactor mounting — it fastens directly to the matching SIRIUS contactor without separate DIN-rail hardware, saving panel width and simplifying the BOM. Rated for motor protection in ATEX-classified atmospheres (DMT 98 ATEX G 001), so it supports Ex e and Ex d installations where the overload relay must be part of the certified protection chain.
Depth of 140 mm, width 70 mm, height 120 mm — the S3 envelope is the largest in the SIRIUS relay range, sized for main-circuit conductors up to 2x (10... 50 mm²) stranded or 10... 70 mm² single stranded. Clearance requirements: zero mm upwards, forwards, backwards, and downwards; only 6 mm at the side. That means the relay can be stacked tight against adjacent devices — no extra breathing gap needed for heat dissipation, though the 7 W per pole dissipation should be considered in sealed enclosures. Auxiliary contact ratings: 1 A at 24 V, 3 A at 120 V, 2 A at 230 V, 1 A at 400 V — these are the switching capacities for the N/O and N/C signal contacts feeding the PLC or safety circuit. The 24 V figure (1 A) is the one to check for 24 VDC control loops. Auxiliary terminals accept 2x (0.5... 1.5 mm²) solid or 2x (0.75... 2.5 mm²) stranded. Shock rated at 8g / 10 ms, operating temperature range -20 to +70 °C, and 100 % relative humidity during operation — suitable for unconditioned industrial floors and washdown-adjacent zones, provided the panel maintains IP20.
Substance prohibitance date of 07/01/2006 aligns with RoHS transition timelines; the relay is compliant with the RoHS directive as implemented by Siemens.
Coordination and selectivity
For type of coordination 1 (no damage to the overload relay under short circuit), a gG fuse rated up to 250 A is required upstream. For type of coordination 2 (the relay remains functional after clearing the fault), the gG fuse must be limited to 200 A. Surge voltage resistance rated at 8 kV.