The Siemens 3UG5643-1CS20 is a digital monitoring relay that tracks current, active current, voltage, power factor, and power on a single device. It accepts a supply voltage of 90 to 690 V AC/DC and measures current from 0.05 to 10 A. The control supply is 24 to 240 V AC/DC, 50/60 Hz. On-delay and tripping delay are independently adjustable from 0.1 to 999.9 s. Outputs are two changeover contacts with screw terminals.
What the ratings mean for fit
The 90-690 V AC/DC supply range means this relay can be powered directly from most industrial control voltages without an external step-down transformer. The 0.05-10 A current input covers motor feeder monitoring, heater bank load tracking, and general branch-circuit current sensing. The 24-240 V AC/DC control supply powers the internal logic and relay coils. The adjustable on-delay and tripping delay (0.1-999.9 s) let you discriminate between momentary inrush and a sustained fault — useful for motor start-up or capacitor bank switching where a brief overcurrent is normal.
Where it fits in the panel
Packaged at 127 x 111 x 38 mm, it occupies roughly the footprint of a standard DIN-rail mounted relay. The screw terminals accept the usual panel wiring without special tooling. The two changeover contacts give one normally-open and one normally-closed set per output, which is enough to drive an alarm lamp and a separate trip signal to a PLC input.