The Siemens 3UG5742-2CW30 is a digital monitoring relay that tracks current, active current, voltage, power factor, and power — all through a single device with Bluetooth connectivity. It handles up to 690 V AC/DC and 15 A, with a universal supply of 24…240 V AC/DC at 50/60 Hz. That wide voltage range means it drops into control panels fed by either 24 VDC or 120/240 VAC without swapping modules.
What the ratings mean for fit
Rated up to 690 V AC/DC and 15 A, this relay covers most motor branch circuits and feeder monitoring inside a standard industrial panel. The 24…240 V AC/DC supply voltage is the same range used across the SIRIUS family, so it shares common control transformer taps and power supplies with contactors and overloads in the same enclosure. On-delay and tripping delay are adjustable from 0.1…999.9 s via two changeover contacts with spring-loaded terminals — that means you get both time-delayed start and fault lockout in one device, no separate timer module needed.
Where it is used
This class of monitoring relay is built for continuous tracking of motor loads, pumps, fans, and conveyor drives — any rotating equipment where you need to see current draw, voltage sag, or power factor drift before a bearing fails or a winding overheats. The Bluetooth link lets a technician read real-time values on a phone or tablet without opening the panel door, which is a real time-saver on a lube route or during a shift-change walkdown.
Terminal and mounting note
Spring-loaded terminals accept 0.2–2.5 mm² solid or ferruled stranded wire. Packaging dimensions are 127 x 111 x 38 mm, so it fits a standard DIN-rail footprint without crowding the next device. Strip length around 8 mm avoids whiskers under the cage. Two changeover contacts give you independent NO/NC pairs for alarm and trip circuits.