A Study on the Detachment Characteristics of the Tramwave Catenary-Free Electrification System for Urban Traffic

Abstract

The tramwave catenary-free system (TCS)—a novel type of electrified transit system for urban railways—receives traction energy from a flexible ground-embedded ferromagnetic strip, which is energized only if a corresponding segment is located underneath the vehicle body. The current collector in the TCS is equipped with an “I-shaped” permanent magnet combination that produces a lifting force on the flexible ferromagnetic strips with octopus-shaped copper sheets located on the surface of the strips underneath the ground. The vehicle’s high-voltage circuit conducts when an electrical contact is maintained by the attractive force of the permanent magnet combination mounted inside the magnetic current collector. However, it has recently been observed that due to the dynamic processes during the electrical contact a severe electrochemical corrosion may occur on the surface of the octopus-shaped copper sheets, which can jeopardize the safe operation of the whole electrified transit system of trams. In order to identify the origins of this electrochemical corrosion, the dynamic characteristics of the TCS have been evaluated with particular attention paid to the impact of eddy currents on the attractive force of the permanent magnet combination under variable operational velocities of vehicles. Based on the dynamic characteristics of TCS, the arc erosion process on the surface of the copper sheet has been reproduced using an arc-discharge experimental platform and the causes of electrochemical corrosion in the TCS have been found. The damage development trends—under increasing speeds of trams—evaluated by the dynamic model of the TCS are consistent with the statistical data for practical damage situations.