Three-phase supply monitoring in the panel
The ABB 1SVR750488R8300 is a CM-MPN.62S three-phase monitoring relay that guards motor and pump circuits against phase loss, phase reversal, and undervoltage conditions. It sits in the control panel alongside the contactor and overload — when a phase drops, the relay opens its output, dropping out the contactor coil before the motor single-phases.
What the monitoring functions cover
It also detects phase reversal: if the phase rotation sequence is incorrect, the relay will not pick up, preventing the motor from running backwards. Undervoltage monitoring is built into the same measurement path — if the line voltage falls below the adjustable threshold, the relay drops out, protecting downstream equipment from brownout conditions. The specific voltage range and time delays are set via the front-panel potentiometers.