Traction Power & Electrical Systems

SYSTRA’s power systems engineers and designers have diverse engineering backgrounds, essential to the successful analysis, design and construction of the many varieties of power distribution systems encountered throughout the transportation industry. We understand the importance of a well-designed power system, which consists of utility interconnections, substations, and power distribution and delivery systems, to enhancing reliability, passenger comfort and safety, and reducing operating costs. SYSTRA’s engineers have specialized project experience in areas such as:

  • Load Flow Analysis
  • Electrical Power System Analysis
  • AC and DC Substations
  • Transmission and Distribution
  • Contact Rail Systems
  • Overhead Contact Systems
  • Signal Power Systems
  • Auxiliary Power Systems

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Representative Projects: 




LIRR/MNR Study of Insulated Joint Arcing
Jamaica, NY


MTA Long Island Rail Road (LIRR), partnering with MTA Metro-North Railroad (MNR), selected SYSTRA to perform a Study to investigate destructive arcing of insulated joints (IJs) in their dc electrified territories. Both MNR and LIRR have experienced excessive destructive arcing from electric multiple unit (EMU) trains passing over the IJs, which has greatly reduced the life-cycle of insulated joints at these locations.

SYSTRA coordinated wayside traction power system testing, vehicle testing, and traction power system analysis to study the phenomena, ascertain the cause(s), and develop possible mitigation of the destructive arcing. SYSTRA followed a systems engineering approach, analyzing the elements of the traction system, vehicle propulsion circuits, and signaling system that utilize the track running rails as electrical elements of their circuits. The study included research, electrical testing, analysis, and development of possible mitigations for the Railroads to consider going forward to address the problem.

Electrical current from the train’s propulsion system is returned through the train wheels and into the rails back to the rectifier substation. The action of a train passing over the IJs in crossovers between two tracks results in the train’s return current utilizing the running rails of both tracks while straddling the IJs. When the last axle of a train crosses the IJs, the return current through one of those tracks is quickly broken – like a switch opening under load. The arc is created by the current being drawn out between the rail and the wheel, inducing a voltage across the IJ due to the rate of change in current in the rails (from a large value to zero) and proportional to the inductive characteristics of the return circuit, including the combination of all wayside and onboard inductances.

In order to examine the traction return circuit, quantify the magnitude of the arc, and categorize the factors contributing to the arc, field testing was conducted to measure the current and resulting voltage during arcing conditions at a variety of locations and train performance conditions. Testing was conducted at three MNR and LIRR locations where arcing had been observed to be significant. The premise was that if electrical limits could be established as a function of the arcing conditions, then methods of mitigation could be categorized and investigated.

Astro-Med recorders were used to measure electrical transients on the wayside and aboard vehicles. Hall effect type clamp-on current probes were used to measure the direct current traction circuits at fouling wires and negative return feeders. Voltage transducers were used to isolate the rails from the test recorder.

SYSTRA SERVICES:
Traction Power
Signal Design
Vehicle Propulsion
Track Design