The green LED lights up when the supply voltage is applied. If each phase voltage
exceeds 195 V (US1) or
exceeds the preset threshold (US2) with respect to the neutral conductor including the hysteresis when the device is switched on, the relay
immediately switches to the operating position. The yellow LED lights up. If at least one phase voltage
falls below the threshold, the relay returns to its normal position and the yellow
LED goes out. If phase 2 also fails, the green LED also goes out.
The neutral conductor must be connected!