The Siemens 3RB2016-2SB0 is a SIRIUS solid-state overload relay for three-phase motor protection. It's a Class 20E trip curve device — that means it allows a 20-second overload at 7.2× rated current before tripping, which is the standard for standard-duty induction motors driving pumps, fans, and conveyors. The solid-state sensing eliminates the bimetal drift you get with thermal relays, so the trip point stays repeatable across ambient swings from -25 to +60 °C.
Mounting and wiring
Mounts directly onto a contactor — the fastening method is contactor mounting, so it clips onto the SIRIUS 3RT contactor range without extra brackets. 45 mm wide, 64 mm high, 73 mm deep; the zero-clearance spacing (0 mm upwards, forwards, backwards, downwards) means you can pack relays side-by-side without derating for heat buildup. Screw-type terminals on both main and auxiliary circuits; main terminals accept solid wire 0.5...4 mm² (or 2× 0.5...2.5 mm²), auxiliary accept 2× 20...14 AWG. Side clearance of 6 mm is the only gap needed.
Electrical ratings and environment
Auxiliary contact ratings cover a wide control-voltage range: 2 A at 24 V, 4 A at 120 V, 3 A at 230 V AC, plus DC ratings of 0.55 A at 60 V, 0.3 A at 110/125 V, and 0.11 A at 220 V. The relay is ATEX certified (PTB 06 ATEX 3001 Ex II (2) GD) for use in potentially explosive atmospheres — the (2) GD means it's associated apparatus for Group II gas and dust zones. Surge withstand is 6 kV; burst immunity at 2 kV on power ports, 1 kV on signal ports (severity level 3 per IEC 61000-4-4). Shock rated at 15g / 11 ms. Operating humidity up to 100% RH.