The 3UG3521-1AG20 monitors a single-pole main circuit (1 pole) with a current sensing range of 2 to 500 mA AC/DC — so it covers low-level motor load or heater current monitoring, not high-current feeders. The output is one CO contact rated for the 120 V AC control supply. No removable terminals on the main or auxiliary circuits; wiring is fixed via the screw connections.
Siemens 3UG3521-1AG20 SIRIUS Monitoring Relay, 2-500 mA, 120
MPN3UG3521-1AG20
Siemens SIRIUS discontinued monitoring relay, 22.5 mm, over/undercurrent monitor 2-500 mA AC/DC, 1 CO contact, AC 120 V 50/60 Hz, 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 the 3UG3521-1AG20?
Snap-on mounting onto a 35 mm DIN rail.
What is the current monitoring range of the 3UG3521-1AG20?
2 to 500 mA AC/DC, covering both over- and undercurrent detection.
Does the 3UG3521-1AG20 have removable terminals?
No, neither the main circuit nor the auxiliary/control circuit terminals are removable.
MPN
3UG3521-1AG20