The operating experience with the northern Italian three-phase network running at 3.6 kV, 16.7 Hz threw up several problems.
With increasing power demands, the voltage was too low and the direct drive to the axles risked overloading the traction motors.
Fewer substations were required but there were more difficulties in the operation of the double overhead contact line, so that maintenance costs were high.
For the latter reason, the line was rebuilt in 1945, after heavy damage in World War II, with 3 kV direct current (DC).
Among the negative results of the test operation was the out-dated equipment of locomotives with rod drive.
As there were sometimes difficulties in this class with overloading of the drive motors, those of the E.470 were put higher and worked via a gear transmission on a jackshaft.
The current, taken from the overhead line and stepped down by the transformer with the optimum power factor, was transferred to the traction motors for propulsion.
Intermediate speeds were achieved by using a liquid rheostat, which allowed uniform acceleration when starting and when changing connections.