DIGITAL MONITORING RELAY FOR THREE-PHASE LINE VOLTAGE AUT. CORRECTION OF PHASE SEQUENCE PHASE FAILURE 3X 160 TO 690V AC 50 TO 60 HZ UNDERVOLT. AND OVERVOLT. 160-690V HYSTERESIS 1-20V OFF DELAY 0-20S 1 W FOR POWER SYSTEM FAULTS 1W FOR PHASE CORRECTION SPRING-LOADED TYPE