PMU distribution line protection automation system is a new line distribution automation system.for slove presentproblem especially of earth fault. which is base on a Distribution Network Synchronous Phasor Measurement-μPMU.PMU (phasor measurement unit), A stand-alonedevice or module. The voltage/current samplingdata are all with a BDS/GPS timestamp accurateto US level.Basic functions:• Phasor: amplitude, phase Angle,• Frequency (f) and Frequency Variation (△f/△t)μPMU Hardware Architecture Block