Impact of rail impedance intrinsic variability on railway system operation, EMC and safety

Running rails in electrified transportation systems are the interface element for several phenomena related to system performance, electromagnetic compatibility and safety: useful voltage at rolling stock, short circuit current, induced voltage, stray current, and track circuit operation. This work presents the physical and mathematical groundings of rail electrical parameters (dc and ac resistance, ac internal and external inductance) and experimental results available in the literature, discussing variability and reliability for each interface. The results consist thus of the identification of the relevant rails longitudinal electrical parameters, the presentation of a set of reliable experimental values, and the discussion of the best approach to manage their variability and uncertainty

How pantograph electric arcs affect energy efficiency in DC railway vehicles

In DC electrified railways pantograph electric arcs represent not only a disturbance, but the step change of the pantograph voltage affects power losses directly and indirectly. The available line voltage is reduced if the train is in traction condition, the arc itself is characterized by ohmic power losses, and the triggered oscillating transient responses are characterized by a net power loss. In addition, if arc occurs during braking the arc voltage suddenly increases the pantograph voltage and may interfere with the dissipative braking chopper, reducing the recovered energy. This work presents the model and analysis of these phenomena with experimental results for arcs measured on a 3 kV dc line in traction and braking conditions

Experimental Characterization of Pantograph Arcs and Transient Conducted Phenomena in DC Railways

open2An electric arc is an example of a transient event that is quite common in electrified transportation systems as by-product of the current collection mechanism. As a broadband transient, an electric arc excites a wide range of (often oscillatory) responses related to the substation and onboard filters, as well as the line resonances and anti-resonances. Similarly do the charging of onboard filter and other related inrush events. This work considers the electrical characteristics of these transients and of the excited responses in order to define their typical spectral signatures in DC railways and take them into account concerning their impact on Power Quality measurements and the measurements of instruments deployed onboard.openMariscotti, Andrea; Giordano, DomenicoMariscotti, Andrea; Giordano, Domenic

Variability and uncertainty of Track Circuit band-pass modeling for interference evaluation

When evaluating track circuits (TC) interference, the latest normative approach indicates the use of band-pass filters that emulate the TC receiver response. The rms value of the output, when compared to the interference limit, indicates whether a specific signal might create interference or not. The implementation of the filter has some degrees of freedom and needs thus to be characterized in terms of added uncertainty to the interference evaluation process. The latter is relevant to safety, strictly related to the incorrect assignment of the status of the track section monitored and protected by the TC itself. When giving a definitive answer about the immunity of a specific TC and the compatibility with the tested rolling stock, it is thus necessary to completely evaluate the uncertainty associated to the chosen model and to the related signal processing operations, even if - it is recognized - their influence may be considered of second order with respect to infrastructure and rolling stock non-idealities

Power Quality in Electrified Transportation Systems

"Power Quality in Electrified Transportation Systems" has covered interesting horizontal topics over diversified transportation technologies, ranging from railways to electric vehicles and ships. Although the attention is chiefly focused on typical railway issues such as harmonics, resonances and reactive power flow compensation, the integration of electric vehicles plays a significant role. The book is completed by some additional significant contributions, focusing on the interpretation of Power Quality phenomena propagation in railways using the fundamentals of electromagnetic theory and on electric ships in the light of the latest standardization efforts

Defense Technical Information Center thesaurus

This DTIC Thesaurus provides a basic multidisciplinary subject term vocabulary used by DTIC to index and retrieve scientific and technical information from its various data bases and to aid DTIC`s users in their information storage and retrieval operations. It includes an alphabetical posting term display, a hierarchy display, and a Keywork Out of Context (KWOC) display

Bonneville International v. Utah State Tax Commission : Addenda

ADDENDUM TO BRIEF OF PETITIONER Petition for Review of the Final Order of the Utah State Tax Commissio