The Siemens 3RB2016-1RB0 is a SIRIUS solid-state overload relay — a 3-pole electronic protector for motor circuits, not a bimetallic thermal unit. It carries ATEX approval PTB 06 ATEX 3001 Ex II (2) GD, so it is certified for use in potentially explosive atmospheres — Zone 2 gas and Zone 22 dust — when paired with an appropriate motor and enclosure. This is not a general-purpose relay; the ATEX marking is the headline spec that governs where it can be installed.
Mounts directly onto a contactor — the fastening method is contactor mounting, not DIN rail. That means it sits on top of a matching SIRIUS contactor (e.g., 3RT10 series) as a single assembly. No separate bracket or rail footprint needed. Main circuit terminals accept solid wire from 0.5 to 4 mm², or 2× (0.5 to 2.5 mm²) — fine for motor leads up to about 4 mm² per phase. Auxiliary terminals take 2× (0.5 to 1.5 mm²) finely stranded with ferrule. The depth is 73 mm, width 45 mm, height 64 mm. No clearance needed upwards, forwards, or backwards — zero mm on all three — so it fits tight against the contactor face. Side clearance is 6 mm.
Electrical ratings and environment
The auxiliary contact ratings are given at multiple voltages: 2 A at 24 V, 4 A at 120 V, 3 A at 230 V, and lower values for DC (0.55 A at 60 V, 0.3 A at 125 V, 0.11 A at 220 V). These are the switching capacities for the built-in auxiliary contacts — useful for signaling the PLC or safety circuit. Per-pole power dissipation is 0.02 W, negligible for panel heat budgeting. It withstands 100 % relative humidity during operation and 15g / 11 ms shock. Surge voltage resistance is 6 kV, and burst immunity meets IEC 61000-4-4 severity 3 (2 kV on power ports, 1 kV on signal ports). Mounting position is any.