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