... phase active energy measuring(three phase three wire, three phase four wire)Wall-mounted installation type, smart designDisplay type: mechanical counter, unit is kWh ... +negative active Indicate of reverse electricityIndicate of open phase fault of A/B/C phaseDisplay data after ... CT connection or direct connectionImpulse constant:3200imp/kWh,400imp/kWhStandard level:1.0class,2.0classPower consumption ...