Product Overview
The Siemens 3UG4501-1AW30 is a SIRIUS level monitoring relay with analog setting, designed to detect conductive liquid levels in tanks, wells, or sumps. It operates on a universal supply of 24 to 240 V AC/DC, making it suitable for both control and industrial power circuits without needing a separate power supply module. The relay's output contacts are rated 3 A at 250 V or 400 V at 50/60 Hz, sufficient for direct switching of small pumps, solenoid valves, or alarm indicators. For DC loads, the contact rating drops to 1 A at 24 V, 0.2 A at 125 V, and 0.1 A at 250 V — a typical derating curve for a general-purpose relay.
Key Ratings and Their Meaning
The supply voltage range of 24 to 240 V AC/DC covers common control voltages worldwide — 24 V DC for PLC-driven panels, 110 V AC for North American installations, and 230/240 V AC for European mains. This eliminates the need for a dedicated transformer or voltage selector. The relay's switching capacity of 3 A at 250 V AC (resistive) is adequate for pilot-duty loads such as contactor coils or indicator lamps. For motor loads, use the contactor's own coil, not the relay directly — the relay is a signal-level device, not a motor starter. The adjustable start-up delay (0.5 to 10 s) and the configurable response threshold (0.85 to 1.1 times the set point) allow the relay to ignore transient splashes or turbulence in the tank, preventing nuisance cycling of the pump. An external reset input enables remote or automatic restart after a fault, which is useful for unattended pumping stations or remote sump installations.
Wiring connections accept 2 x (20-14 AWG) solid or stranded conductors, which covers standard panel wire sizes. The spring-cage terminals (implied by the fastening method) provide vibration-resistant connections.