Switch between motoring and braking to see where the energy goes in each loco, first on the side view and then stage by stage. When motoring, both draw from the 25 kV line. When braking, the WAP7 sends power back up the wire; the WAP4 turns it into heat on the roof.
Side views show the levels the plans on Layout hide. On the WAP7 the transformer hangs under the floor, directly below the two converters. On the WAP4 the transformer stands inside the body and the smoothing reactors hang underneath. Scroll sideways on a phone.