Product Overview
The Siemens 3UG4621-2AW30 is a SIRIUS current monitoring relay with digital setting, designed to monitor AC or DC current in the range of 0.003 to 0.5 A (measurable up to 0.6 A). It provides an adjustable trip threshold and a configurable start-up delay of 0.1 to 20 seconds, with auto-reset or external reset capability. The relay operates on a wide supply voltage range of 20.4 to 264 V AC (50/60 Hz) or DC, making it suitable for global control panels without a separate power supply module. Its output contacts are rated 3 A at 250 V or 400 V AC, sufficient for signaling to a PLC or direct switching of small loads.
The 0.003–0.5 A current range covers low-level monitoring for motor protection, heater current, or small transformer loads. The measurable current extends to 0.6 A, providing headroom for applications near the upper limit. For a sourcing decision: if your protected load draws less than 3 mA, this relay will not detect it; if it exceeds 0.6 A, you need a higher-range unit. Pollution degree 3 confirms suitability for industrial atmospheres with conductive contamination. The LCD display shows the actual current value and trip settings, aiding commissioning and fault finding without a separate meter.
Any mounting position is permitted. The 22.5 mm width and 94 mm height with 91 mm depth leave clearance for adjacent devices. The relay provides galvanic isolation between input and output and between outputs, which is critical for maintaining separation between control and monitored circuits in a panel. The 1 A at 24 V DC contact rating is sufficient for PLC digital inputs; at 125 V DC it drops to 0.2 A, and at 250 V DC to 0.1 A — note the DC derating if switching DC loads.