The Siemens SIRIUS 3UG4651-2AW30 is a speed monitoring relay with digital setting, purpose-built to track RPM on rotating machinery and trip when the shaft speed strays outside the programmed window. It runs on a universal control supply of 24 to 240 V AC/DC, so it drops into panels with mixed voltage rails without needing a separate power module. The relay output is rated 3 A at 250 V AC — enough to directly switch a contactor coil or a small motor starter.
Configuration and wiring notes
Terminal screws accept two conductors per clamp. The LCD display shows the actual RPM and the setpoint during programming. Auto-reset and error memory are both available, so the relay can either latch on fault or self-recover when speed returns to normal. External reset input lets a PLC or pushbutton clear the fault remotely. Start-up delay adjustable 1 to 900 seconds avoids nuisance trips during motor acceleration.