The 3UG3521-1AC20: The 2...500 mA sensing range is the full-scale span for both over- and undercurrent monitoring — set the trip point anywhere inside that window. The 1 CO contact is a single form-C relay output rated for the control voltage; it changes state when the monitored current crosses the threshold. Screw terminals on both main and control circuits keep wiring straightforward for panel retrofits.
Siemens 3UG3521-1AC20 SIRIUS Monitoring Relay, 2-500mA, 24V
MPN3UG3521-1AC20
Siemens SIRIUS discontinued type monitoring relay, 22.5mm, over or undercurrent monitor, 2...500mA AC/DC, 1 CO contact, AC 24V 50/60Hz, screw connection, snap-on mounting.
Sourced new & surplus through independent channelsAuthenticity-screened · ESD-safe packingListing updated Jul 2026
Specifications
| Parameter | Value |
|---|---|
| Product line / brand name | SIRIUS |
| Parameter | Value |
|---|---|
| Mounting type | snap-on mounting |
| Parameter | Value |
|---|---|
| Removable terminal for main circuit | No |
| Reference code acc. to DIN EN 61346-2 | K |
| Reference code acc. to DIN EN 81346-2 | K |
| Number of poles for main current circuit | 1 |
| Removable terminal for auxiliary and control circuit | No |
Product details
Frequently asked questions
What is the mounting type for this relay?
Snap-on mounting onto a 35 mm standard mounting rail per DIN EN 50022.
What is the sensing current range?
2...500 mA AC/DC, adjustable within that span for over- or undercurrent monitoring.
MPN
3UG3521-1AC20