The ABB Entrelec 1SVR730840R0500 is a 3-phase voltage monitor on a DIN-rail form factor, covering a 24-240V AC/DC control range. It provides over- and under-voltage protection with three selectable measuring ranges (0.3-1.5 FLA, 1-5 FLA, 3-15 FLA) and an adjustable trip delay of 1-30 seconds. The output is two SPDT contacts, giving you independent alarm or control paths for each fault condition.
The 24-240V AC/DC control range means this relay powers itself from the monitored circuit across a wide voltage band — no separate control supply needed. The three FLA ranges let you match the monitor to motor nameplate current without an external CT. The 1-30 second trip delay prevents nuisance tripping on momentary sags or inrush; set it longer than the motor start time. Two SPDT outputs give you one contact for alarm and one for trip, or a redundant safety path.
Snaps onto standard 35mm DIN rail inside a motor control center or distribution panel. The wide AC/DC supply range means it can share a backplane with 24V PLCs or 230V contactors without a dedicated power supply. The three-phase monitoring catches phase loss, phase reversal, and undervoltage on motor feeds — common failure modes on conveyor drives and pump starters.