The Siemens SIRIUS 3UG4583-2CW31 is an insulation monitoring relay with an analog setting scale — it continuously measures the insulation resistance of an ungrounded AC or DC system and trips an output when the value drops below the set threshold. It monitors AC systems from 0 to 400 V and DC systems of the same voltage class, across line frequencies from 15 to 400 Hz. The control supply voltage accepts 24 to 240 V AC/DC.
The 45 mm width fits a single slot in most distribution boards. Spring-loaded terminals accept solid wire 20-16 AWG (2x conductors) and stranded 18-16 AWG (2x conductors), or finely stranded with ferrule 0.5-1.5 mm². No screw tightening needed — strip, push, done. Mounting position is any — horizontal, vertical, upside down — the relay doesn't care.
Setting and response
An error memory option (yes) latches the alarm after a fault clears, so the condition isn't lost on a transient recovery. Delayed switching of 2 seconds prevents nuisance tripping on momentary ground faults or switching transients — typical for motor starts or capacitive coupling on long cable runs.
Environmental and electrical robustness
Surge voltage resistance of 4000 V means the relay withstands transient overvoltages common in industrial power systems without failing — important for IT (ungrounded) systems where the first fault doesn't clear and the voltage to ground can rise.