Voltage Band Relays provide protection to equipment that is required to operate within an upper and lower voltage limit. As long as the operating voltage remains within an Over and Under Voltage range, the internal relay stays energized. If the operating voltage falls outside this range, the relay will drop-out.
The over voltage setting (Umax) is adjustable across the full range as shown in the table below. The under voltage setting (Umin) is adjustable from 75-95% of the over voltage setting (Umax). The relay energizes (and the LED is Red) when the monitored voltage is between the over and under voltage settings. The relay de-energizes (and the LED is Green) when the monitored voltage falls outside the over or under voltage settings for a period longer than the drop-out time delay (t), which is adjustable from 0.1 to 10 seconds. The relay re-energizes when the monitored voltage returns to a value between the over and under voltage settings for a period longer than the pick-up time delay, which is fixed at 0.5 seconds.
