The AC voltage monitoring relay type E27/59A is a digital relay and designed to monitor a three-phase supply and single-phase supply by checking all phase are pleasant and within set voltage limit. An adjustable time delay is incorporated to avoid nuisance tripping. When power is applied to relay, the green LED will illuminate (Healthy function) or watchdog function is working. The relay is provided with an adjustable voltage of 80 ~ 100% Un on under voltage unit and 100 ~ 120% Un on over voltage unit with time delay 0 ~ 60 seconds set point.
Under Voltage Function (E27A)
When the monitor voltage falls below the set point, the time delay is started and the red LED (Under voltage LED display) start flashing until time delay has reached the set point value. (The response time of the relay is adjustable between 0 to 60 seconds) Then the red LED stop flashing but steady on, simultaneously with relay energizes or switches to its operating position. The relay will automatically reset once the monitored voltage rises above the set point. When reset, the LED will extinguish at the same time if time delay is not activated.
Over Voltage Function (E59A)
As it is common with all AC voltage monitoring relays, on over voltage unit the relay energizes when the monitor voltage exceeds and the response value is selected, the time delay is started and the orange LED (Over voltage LED display) start flashing until time delay has reached the set point value. Then the orange LED stop flashing but steady on, simultaneously with relay energizes. The relay will automatically reset once the monitored voltage falls below the set point. When reset, the LED will extinguish together in case of time delay is not activated.
This type is also designed to use with the auxiliary supply source from 90 to 250 VDC. In case of AC voltage from VT or main source are failed, the relay will still working (or status of relay is O.K. when AC input voltage are failed)