IF articles

It is a well known fact that when the

catenary supply system is mechanically disturbed, electric

arcs may develop on contact between the catenary and the

pantograph. The variation in supply voltage, due to the

voltage drop across the arc, generates current harmonics

which can disturb the signalling system’s track circuits.

This phenomenon is particularly noticeable in double pantographs

operation since the second pantographs finds

catenary disturbed by the passing of the first pantograph.

The deterioration of the quality of the current collection

depends on numerous factors (the mechanical characteristics

of the catenary and pantographs for example, the

distance between pantographs, vehicle speed etc.), whilst

the effects of this worsening in harmonic content of the

current collected depend on the type of current filtering

and the traction driving control system.

The current study aims to equip the railway drive

designer with a preliminary calculus methodology of

the harmonic content of the current collected allowing

identification of the most appropriate changes to be

made to the input filter and/or the control system. The

proposed methodology is applied to the evaluation of

the response of a typical protection apparatus from undesired

effects of the harmonics in case of multiple collection

implemented for a double unit vehicle (as can

be the case where an increase in transport supply is required).