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