The VM series Over/Under Voltage Relay provides protection to equipment where either an over or under voltage condition is potentially damaging. It is designed to operate when the operating voltage reaches a preset value and drop-out when the operating voltage drops to a level below the preset value. The pick-up voltage setting is user-adjustable from 85 to 115% of the nominal voltage rating. The relay energizes when the monitored voltage is above the pick-up setting. The relay de-energizes when the monitored voltage is below the drop-out setting for a period longer than the dropout time delay (t), which is a fixed 500ms for VM Series products.