I have noticed that when driving the TGV in the DC area the train has both pantographs raised but lowers one of them in the TGV power area. Why does the train do this, the only reason I could think of was for the train to be able to drag more current out of the lines. I've hear that the train only uses one pantograph in the TGV area due to drag which sounds reasonable but is that true?
Under DC catenary the intensity is so high that each locomotive is taking up electricity by itself as the cable will melt if it was going from one to another locomotive, but on the opposite under AC catenary as the intensity is not the same the rear locomotive collects the electricity and it goes through the cable on the roof the the front one.
There's 17 times higher voltage on the LGV section, so although the trainset draws more (it's about 2.5 times more powerful under AC), the current going through the cables is still fractional compared to DC.
There are potential engineering difficulties with multiple pantographs when running at high speeds. The first contact with the wire creates a slight 'ripple' effect, which can propagate along the wire and interfere with the second connection. The wife of a friend (an Oxford applied maths tutor) did research on this for BR at the time of the APT.
Would it be that big of a difference, given that two coupled TGV sets run one pantograph each? The distance between the two pantographs is only one loco longer. And this ripple effect would probably be greatly influenced by the fact TGV pantos on LGV are not pushing against the wire that much as they're rather locked at a constant height. These are probably a bit difficult question to answer, but an interesting food for thought.
Pantograph (collector) on DC, has a slip made of carbon with copper admixture. It also exerts more pressure on the contact wire. The DC pantograph is modified for a greater flow of electric current. In the AC pantograph, the slide is made of copper with admixture of carbon. AC and DC dual-system locomotives have their own pantographs for each power system.
It has to do with the strip material and length of the strip DC pantograph is 1.95m Metalized Carbon while AC Pantograph is 1.45m Carbon strip. The special case is TGV Duplex 2N2 3UA which is the correct train for the route towards Frankfurt in the station PIS it's spelt as Francfort sur le Main Gare Centrale where the DC pantograph 1.95m Metalized Carbon strip is used for 15kv 16.7hz AC Germany and Austria. For a German locomotive that uses DC Metalized Carbon strip on 15kv 16.7hz its the DB Baureihe 180 DR Baureihe 230 Knödelpress found on Nahverkehr Dresden
