On the load demand changing, the controller signals {HEAD ~ the frequency converter} to give {TAIL ~ a changed new power output} to meet the changed demand 
to give
On the load demand changing , the controller signals { HEAD ~ the frequency converter } to give { TAIL ~ a changed new power output } to meet the changed demand
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH