This feedback system keeps {HEAD ~ the heat} of {TAIL ~ the welding process} at a given selected and desired level 
of
This feedback system keeps { HEAD ~ the heat } of { TAIL ~ the welding process } at a given selected and desired level
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH