Commuter Rail AC Electrification Load-Flow Simulation Report - RTD

Commuter Rail AC Electrification Load-Flow Simulation Report Revision 1
In order to prevent overheating and annealing of the catenary system conductors, the conductor
RMS currents predicted by the study should be well below the conductor ampacities. The
ampacity of the feeder and messenger wires, shown in Table 3, were obtained from the
Westinghouse Reference Book 6 . The ampacity of the contact wire, shown in Table 3, was
obtained from the AREMA Manual 7 . The ampacities were calculated based on the following
conditions:
• Ambient air temperature 77° Fahrenheit,(25°Celsius),
sunny conditions
• Conductor operating temperature, Copper 167° Fahrenheit, (75°Celsius)
• Conductor operating temperature, Alloys 121° Fahrenheit, (100°Celsius)
• Emissivity 0.5
• Wind velocity 2 feet/second, (0.61 m/s)
• Contact wire wear 30%, (70% of the conductor original
cross-section area remains)
The ampacities will be actually somewhat lower, since the ambient temperature in Denver can
reach 40° Celsius.
5.3 POWER DEMANDS
5.3.1 Power Demand Characteristics
Traction power substations experience highly fluctuating loading due to the abrupt, impulse-like
changes in power requirements of trains as they accelerate, decelerate, or as they encounter or
leave track grades. The magnitude and frequency of the impulses increase during peak power
demand time periods, since longer trains are likely to operate at shorter headways. Therefore
the power demand also fluctuates in the same manner as the load. The rush hour period
occurs twice a day, in the morning and in the afternoon, and the maximum power demands
usually occur during this time. For traction power substations to supply this load cycle, the
substation equipment must have sufficient continuous and overload power ratings as
recommended by the AREMA guidelines.
6 Westinghouse Electric Corporation, Electrical Transmission and Distribution Reference
Book, published in 1964.
7 AREMA, Manual for Railway Engineering, Chapter 33, Electrical Energy Utilization, Part 4,
Railroad Electrification Systems, published in 2006.
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