The Siemens 3UG4822-2AA40 is a SIRIUS current monitoring relay with a digital setting and LCD display, covering a measurable current range of 0.05...10 A. It runs on an 18...30 V DC supply and provides a relative repeat accuracy of 1%, so the trip point stays tight across the range — no fiddling with trimmers to get a repeatable threshold. The relay output is rated for 3 A at 250 V and 400 V at 50/60 Hz, and the auxiliary contacts handle 1 A at 24 V, 0.2 A at 125 V, and 0.1 A at 250 V.
Clearance around the unit: 0 mm upwards, forwards, backwards, downwards, and at the side, so it can be packed tight against other devices without derating for airflow.
It carries IP20 protection (finger-safe terminals) and a pollution degree of 2, which is the usual spec for clean, enclosed control panels.
IO-Link and reset options
IO-Link communication runs at COM2 (38.4 kBaud), so it can report the actual current value and fault status to a master without extra analog wiring. Auto-reset and external reset are both supported, giving flexibility for unattended restart or manual intervention after a fault clears. A start-up delay of 0...999.9 s is configurable, useful for filtering out inrush on motor starts or compressor cycles.