The Siemens 3UG5816-1AA40 is a digitally adjustable monitoring relay from the SIRIUS line monitoring family, designed to supervise three-phase mains for phase failure, phase sequence, asymmetry, frequency deviation, overvoltage, and undervoltage. It accepts a supply range of 90 to 690 V AC (15 to 70 Hz) and provides one changeover contact. The built-in IO-Link interface lets a PLC or IO-Link master read measured values and reconfigure thresholds remotely.
The 90–690 V AC operating range covers standard low-voltage mains from 110 V to 480 V without needing a separate control transformer — one part number for the whole plant voltage spread. The 15–70 Hz frequency window handles both 50 Hz and 60 Hz grids plus variable-frequency gensets or emergency supplies that drift below 50 Hz. The single changeover contact (SPDT) is rated for the control circuit, not the motor power; it switches the PLC digital input or the contactor coil, so the relay itself draws only the loop power from the IO-Link master. The digital adjustment means no trim pots to drift or seal after commissioning — all thresholds and hysteresis are set via IO-Link or the front-panel buttons. For a brewery CIP skid or a cement kiln feeder, that makes the relay traceable: the IO-Link master logs the parameter set, so every batch or shift change is documented without a technician tweaking a dial.