Phase monitoring relay for three-phase systems
The ABB 1SVR760487R8300 is a phase and voltage loss relay from the CM-MPN.52P series, designed to monitor three-phase mains for phase failure, phase sequence reversal, and undervoltage conditions.
What the phase-loss detection means for your line
A phase-loss relay like this one drops its output when one of the three phases falls below the pickup threshold — typically around 80% of nominal. That prevents a motor from single-phasing, which would draw locked-rotor current on the remaining phases and burn the winding in minutes. The CM-MPN.52P also checks phase sequence, so if a motor leads are swapped during maintenance, the relay holds the contactor open until the rotation is corrected. This saves a callout for a phase-rotation meter at startup.
Sourcing this relay for a BOM line
If you're replacing an older ABB phase-loss relay, confirm the wiring diagram matches; the terminal layout can vary between series.