Award Date

December 2023

Degree Type


Degree Name

Doctor of Philosophy (PhD)


Electrical and Computer Engineering

First Committee Member

Robert Schill

Second Committee Member

Yahia Baghzouz

Third Committee Member

Biswajit Das

Fourth Committee Member

Hualiang Teng

Number of Pages



The weakest link in powering high-speed rail locomotives is the carbon strip of a pantograph collector which makes physical contact between the overhead power line and the electrical supply wires of the locomotive. A means of detecting and distinguishing between static degradation effects of the carbon strip by monitoring the locomotive’s input current line is presented. It was hypothesized that the transient nature of the current flow in the locomotive’s input power line and hence the magnetic field it generates can be used to characterize and monitor the carbon strip’s integrity. Further, it was hypothesized that the electromagnetic dot (EM dot) sensor is sensitive enough to monitor the magnetic field and changes in the magnetic field generated by the current in the locomotive’s input power lines.

A pulsed-power carbon strip degradation test stand was designed, built, and tested based on static degradations. The test stand was designed to operate in single-pulse mode and multi­pulsed mode. Short, high-energy pulses generated in the test stand were used to monitor the changes on the carbon strip. Driven by a 5 kV DC source, a 3.3 µF capacitor (rated at 25 kV DC) releases its energy to the trainload resistor, RL (1 Ω < RL < 7.5 Ω) by way of a discharge tube switch (operating in a self-breaking mode) in series with the carbon strip. Based on Paschen's effects, the self-breaking switch exhibits closure at desired breakdown voltage as dictated by the tube pressure. An extensive circuit theory (with MATLAB), an independent computer-aided design, analysis, and circuit simulation tool (LTspice), and an in-line current measuring resistor were used to study the charge and discharge properties of the test stand and to corroborate experimental results using the electromagnetic (EM) dot with respect to theory and simulation. The EM-dot is a compact UNLV patented time-varying and, with initial transients, DC measuring electric and magnetic field sensor. All four studies showed reasonably good agreement.

The EM dot was sensitive enough to distinguish the static groove faults from the carbon strip in its new, unblemished state to its shorted state (including other resistance of different grooves) for trainloads less than 2.2 Ω. The carbon strip electrical resistance ranges between 3 mΩ ≤ Rc ≤ 28 mΩ, where the electrical short state occurs at Rc = 3 mΩ and the new, unblemished state occurs at Rc = 28 mΩ.


Carbon Strip; Discharge properties; High-speed railroad; Pantograph-Catenary System; Pulsed power; Railroad electrification


Electrical and Computer Engineering | Electromagnetics and Photonics | Engineering Physics | Transportation

File Format


File Size

9330 KB

Degree Grantor

University of Nevada, Las Vegas




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