What it is and what it does
The Siemens 3RB2046-2UB0-ZX95 is a SIRIUS solid-state overload relay — a CLASS 20E trip curve device that protects three-phase motor circuits from sustained overcurrent without the mechanical wear of a bimetallic strip. It mounts directly onto a contactor (fastening method: contactor mounting), so the assembly stays compact on the DIN rail and the power wiring runs straight through without extra terminal blocks. The ATEX approval (PTB 06 ATEX 3001 Ex II (2) GD) qualifies it for use in potentially explosive atmospheres.
Key ratings and what they mean for fit
CLASS 20E trip curve allows 20 seconds of locked-rotor current before tripping — a standard match for general-purpose induction motors. Three poles for the main current circuit, screw-type terminals accepting solid conductors from 0.5 to 4 mm² and stranded from 10 to 70 mm². Auxiliary and control circuit terminals are also screw-type, rated for 2 A at 24 V, 4 A at 120 V, and 3 A at 230 V — enough to switch a PLC input or a small contactor coil directly. Surge voltage resistance rated at 8 kV and burst immunity at 2 kV on power ports (IEC 61000-4-4 severity 3) — the relay holds up in industrial panels near VFDs or welding equipment without external suppression. Shock resistance of 15g / 11 ms and any mounting position — install it on a panel door or a machine frame without derating.
Where it goes and how it mounts
Contactor mounting — clips directly onto the matching SIRIUS contactor so the power terminals align. Dimensions: 70 mm wide, 106 mm tall, 124 mm deep. Side clearance of 6 mm is required; zero clearance above, below, forwards, or backwards — so it packs tight against adjacent devices. Operating temperature range of -25 to +60 °C with 100 % relative humidity — no condensation worry in washdown areas as long as the enclosure is rated for it.
Lifecycle and sourcing reality
RoHS compliance date of 07/01/2006 means it meets the original EU RoHS directive.