The Siemens 3UG5501-1AW30 is an analog monitoring relay from the Level Monitoring family, designed to watch resistance from 0.5 to 500 kOhm and trigger on overshoot or undershoot of the setpoint. It runs on a universal supply of 24 to 240 V AC/DC at 50/60 Hz, so it fits panels with mixed control voltages without needing a separate power supply module.
The resistance monitoring range (0.5 to 500 kOhm) covers common level probes, conductive liquid sensors, and resistive transducers. The relay can be configured for 2-step or 1-step control, meaning it can handle both high/low alarms or a single threshold with hysteresis. The tripping delay is adjustable from 0.5 to 30 seconds, which lets you ignore brief splashes or turbulence in a tank before the relay changes state. Output is a single changeover contact. The supply voltage range is 24 to 240 V AC/DC.