The Siemens 3RB2133-4UD0 is a SIRIUS solid-state overload relay for three-phase motor protection. It mounts directly to a contactor (contactor mounting per the specification) and provides adjustable trip classes 5E, 10E, 20E, and 30E, letting you match the thermal curve to the motor start profile — a 5E setting for fast-starting pumps, 30E for high-inertia loads like centrifuges.
Three poles for the main current circuit, with screw-type terminals accepting 1 x 18–2 AWG or 2 x 4 AWG max (finely stranded 1–35 mm²). The auxiliary and control circuit uses spring-loaded terminals (2 x 24–16 AWG, solid 2 x 0.25–1.5 mm²). This terminal split is common on SIRIUS overloads: the power path gets a high-torque screw clamp for vibration resistance, while the signal/aux side gets tool-less spring cages for faster wiring. Surge voltage resistance rated at 6 kV, with burst immunity per IEC 61000-4-4 severity 3 (2 kV on power ports, 1 kV on signal ports). That places it in the same noise-immunity class as the contactor it mounts to — no additional suppression needed for standard industrial panels. The auxiliary contact ratings cover both AC and DC control voltages: 4 A at 120 V AC, 3 A at 230 V AC, 2 A at 24 V DC, 0.55 A at 60 V DC, 0.3 A at 125 V DC, and 0.11 A at 220 V DC. These are the make/break capacities for the N/O and N/C contacts feeding the PLC input or holding circuit.
Operating temperature range -25 to +60 °C, storage and transport -40 to +80 °C, with 100 % relative humidity during operation. Shock resistance 15g / 11 ms. Mounting position any.