... supply voltage is too high, low voltage, phase, reverse phase (phase sequence), to voltage unbalance relay protection, products ... , pumps, fuel pumps, central air conditioning units, electrical control boxes, distribution cabinets, cranes, etc., such as central ... the five lights are to indicate: normal phase (phase voltage imbalance), reverse phase, overvoltage, undervoltage.3) Dimensions:79mm×23mm× ...