What it is and what it does
The Siemens 3RB2046-1UB0 is a SIRIUS solid-state overload relay — it protects three-phase motor circuits by monitoring current and tripping if an overload condition persists beyond the CLASS 10E curve. CLASS 10E means the relay will trip within 10 seconds at 7.2× the set current (cold start), which is the standard for standard-duty induction motors driving pumps, fans, and conveyors. Three poles for the main current circuit, with screw-type terminals on both the main and auxiliary/control sides. The main terminals accept solid wire from 0.5 to 4 mm² (or 2x 0.5 to 2.5 mm²) and stranded from 10 to 70 mm² (or 2x 10 to 50 mm²). AWG equivalents: 2x 10 to 1/0, or single 10 to 2/0. Auxiliary terminals take 2x 20 to 14 AWG. Mounts directly onto a contactor via the fastening method — no separate DIN-rail bracket needed, which saves panel space. Mounting position is any, so you can orient it to fit tight enclosures. Clearance: 0 mm upwards, forwards, and backwards; 6 mm at the side.
Key ratings and what they mean for fit
The auxiliary contact ratings tell you what control voltage the relay can switch. At 24 V it handles 2 A; at 120 V it handles 4 A; at 230 V it handles 3 A. For DC loads: 0.55 A at 60 V, 0.3 A at 110/125 V, 0.11 A at 220 V. These are the make/break capacities for the signalling contacts — useful for feeding a PLC input or a contactor coil. Surge voltage resistance rated at 8 kV, and immunity to electrical fast transients (burst) per IEC 61000-4-4 at severity level 3: 2 kV on power ports, 1 kV on signal ports. That means it's designed to hold up in industrial environments with switching transients from contactors and drives. Shock resistance rated at 15 g for 11 ms, so it can handle the vibration you'd see on a machine-mounted panel or near a large motor. Operating temperature range is -25 to +60 °C; storage and transport from -40 to +80 °C. Relative humidity during operation up to 100 %, including condensation — no derating needed for wet environments. Power dissipation per pole is 0.02 W — negligible heat, so you don't need to worry about thermal buildup inside a crowded panel.
Where it goes and compliance
This is a solid-state overload relay for the SIRIUS family, designed to sit between a contactor and the motor in a standard motor starter assembly. The ATEX approval (PTB 06 ATEX 3001 Ex II (2) GD) means it can be used in the control circuit of equipment installed in potentially explosive atmospheres — it's associated apparatus, not the field device itself, but it allows the starter to be part of a certified safety chain. Reference code per IEC 81346-2 is F (protective device). Substance prohibitance date of 07/01/2006 aligns with RoHS compliance (no date-specific RoHS statement, but the date matches the EU RoHS exemption sunset).