The magnitude of a power component common to all the power sources or frequency, if the power sources are AC generators driven by constant speed drives, is compared to {HEAD ~ a reference} to provide {TAIL ~ an error signal} 
The magnitude of a power component common to all the power sources or frequency , if the power sources are AC generators driven by constant speed drives , is compared to { HEAD ~ a reference } to provide { TAIL ~ an error signal }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL