The electric power supplies are provided with {TAIL ~ respective positioning and actuating devices} controlled to actuate them independently from one another during setting in {HEAD ~ contact} and detachment of the bars 
The electric power supplies are provided with { TAIL ~ respective positioning and actuating devices } controlled to actuate them independently from one another during setting in { HEAD ~ contact } and detachment of the bars
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH