page_title: Amtrak's 25 Hz traction power system
section_title: Specifications and statistics
hierarchical_section_title: Amtrak's 25 Hz traction power system / Specifications and statistics
caption_attribution_description: English: Photograph of West Philadelphia Substation of the Pennsylvania Railroad. Note similarity to Paoli substation design.
context_page_description: Amtrak's 25 Hz traction power system is a traction power grid operated by Amtrak along the southern portion of its Northeast Corridor: the 225 route miles between Washington, D.C. and New York City and the 104 route miles between Philadelphia and Harrisburg, Pennsylvania. The Pennsylvania Railroad constructed it between 1915 and 1938. Amtrak inherited the system from Penn Central, the successor to Pennsylvania Railroad, in 1976 along with the Northeast Corridor. This is the reason for using 25 Hz, as opposed to 60 Hz – which is the standard for power transmission in North America. In addition to serving the NEC, the system provides power to New Jersey Transit Rail Operations, the Southeastern Pennsylvania Transportation Authority and the Maryland Area Regional Commuter Train. Only about half of the system's electrical capacity is used by Amtrak. The remainder is sold to the commuter railroads who operate their trains along the corridor.
context_section_description: The 25 Hz system was built by the Pennsylvania Railroad with a nominal voltage of 11.0 kV. The nominal operating voltages were raised in 1948 and are now:
  Catenary (Traction) Voltage : 12.0 kV
  Transmission Voltage: 138 kV
  Signal Power:
  2.2 kV 91⅔ Hz – NY Penn Area. 60 Hz used 1910–1931. 100 Hz installed but quickly changed to avoid interference caused by simultaneous AC and DC electrification.
  3.3 kV 100 Hz – Paoli/Chestnut Hill. 60 Hz used 1915/18–1930.
  6.9 kV 91⅔ Hz – all electrification work from 1930 onward.
  As of 1997, the system included:
  951 miles (1,530 km) of 138 kV transmission line,
  55 substations,
  147 transformers, and
  1104 miles of 12 kV catenary.
  Over 550 GWh of energy are consumed annually by locomotives on the system. If this were consumed at a constant rate over the entire year (although it is not in practice), the average system load would be approximately 63 MW.
  The system power factor varies between 0.75 and around 0.85.
caption: West Philadelphia substation 1915
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