1 phase over/under voltage relay HUL, HUH

HUL and HUH control relays are used for monitoring 1-phase AC/DC voltages. The relay automatically detects the form of voltage that is to be measured. The relay requires a supply voltage. Using a rotary switch, selection can be made between over- or under-voltage, with or without memory. The switch position and consequently the control relay's function mode is detected when the operating voltage is switched on. If the switch is in the wrong position, the relay will remain deactivated and the LEDs will flash to indicate incorrect setting. If the switch position is changed during operation, all LEDs begin to flash but the unit will continue to function normally with the voltage set at the most recent power connection. The LEDs return to normal function when the switch has been returned to its original position, which was set before the first power connection. The limit value for over- or under-voltage is set with a potentiometer that is scaled in the percentage of the voltage range that is to be monitored. The hysteresis value is similarly set with a scale from 5-50 % of the set limit value. The hysteresis value cannot exceed the measurement range's limit value. Both relays are equipped with a time delay (Tt) to ignore temporary voltage deviations. Green LED (Un) indicates supply voltage OK. Yellow LED (R) indicates active relay output.