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