Individual sensors sense {HEAD ~ the magnitude} of {TAIL ~ a variable power component} from each power source and provide a signal proportional thereto 
of
Individual sensors sense { HEAD ~ the magnitude } of { TAIL ~ a variable power component } from each power source and provide a signal proportional thereto
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH