The Model 263 continuously monitors 3-phase power systems for phase loss, low voltage and phase reversal. The monitor consists of a solid-state sensing circuit, driving an electromechanical relay.

Applying correct voltage and phase rotation energizes the relay. When properly adjusted, a fault condition will cause the relay to de-energize, even when regenerated voltage is present.

When the fault is corrected, the Model 263 automatically resets. A manual reset version and an option for gold-plated contacts are also available.

The Model 263 does not require a neutral connection, and can be used on Wye or Delta systems. Each of the five different voltage ranges is adjustable to allow the monitor to be set for existing conditions. NORMAL and TRIP LED indicators are provided to aid in adjustment and system troubleshooting.