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