By having such a method, {HEAD ~ the sensors} determine the impedance in {TAIL ~ a power line} and compare that impedance with an initial impedance profile for the power line 
By having such a method , { HEAD ~ the sensors } determine the impedance in { TAIL ~ a power line } and compare that impedance with an initial impedance profile for the power line
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH