Siemens 3UG4633-1AL30 Digital Voltage Monitoring Relay

Siemens 3UG4633-1AL30 is a digital voltage monitoring relay that provides a single changeover contact to guard electrical circuits against undervoltage and overvoltage. In a compact 22.5 mm form factor with screw terminals, it accepts a supply range of 17 to 275 V AC/DC and operates on 50/60 Hz. The device includes a programmable spike delay from 0.1 to 20 seconds and a hysteresis range of 0.1 to 150 V, enabling precise definition of the voltage window that triggers the output. It is available with or without an error buffer to log faults, and it features a single changeover contact that can be wired to control circuits or indicators. This digital monitoring relay is intended for protection of control panels, power supplies, and other equipment where preserving voltage within tolerance is critical. Siemens positions the 3UG4633-1AL30 within the SIRIUS family of digital monitoring relays, and catalogs note its status relative to newer successors such as 3UG5643-1CS20 and 3UG5533-1AL30.