Amtrak's 25 Hz traction power system

The Safe Harbor Dam generates 25 Hz railroad power via two turbines in the east end of the turbine hall and an M-G set outside against the Dam face.

• Safe Harbor Dam, PA – The Safe Harbor Dam has two 28 MW, single phase, turbines dedicated to 25 Hz power generation. A 25 MW bi-directional motor generator type frequency converter is also installed. The total 25 Hz capacity of the dam is 81 MW. Power from Safe Harbor is transmitted via the Conestoga substation to Royalton, Pennsylvania, Parkesburg, Pennsylvania (two circuits), and Perryville, Maryland (four circuits) where it is fed into the lineside 138 kV network.

The 25 Hz machines at the dam are scheduled by Amtrak but owned and operated by Safe Harbor Water Power Company. Like other hydroelectric plants, it also has excellent black start capability. This was most recently demonstrated during the 2006 blackout. After a cascade shutdown of converters had left the network de-energized, it was recovered using Safe Harbor's generators, and the other converters subsequently brought back online.

During the twelve-month period ending August 2009, Safe Harbor supplied about 133 GWh of energy to the Amtrak substation at Perryville.[5] Typically, two thirds of the Safe Harbor output is routed through Perryville, the remainder being sent through Harrisburg or Parkesburg. This suggests that Safe Harbor supplies around 200 GWh of energy annually into the 25 Hz network.

Motor-generators and steam turbine generators were the original power sources on the PRR traction power network. The last steam turbine shut down in 1954, but some of the original motor generators remain. Although the converting machines are frequently called 'rotary converters' or 'rotary frequency converters', they are not the rotary converter used frequently by subways to convert low-frequency alternating current to DC power. The converters used are more precisely described as motor generators and consist of two synchronous AC machines on a common shaft with different ratios of poles; they are not electrically connected as in a true rotary converter.

Principal advantages of motor generators include very high fault current ratings and clean output current. Solid state electronics can be damaged very quickly, so the microprocessor control systems react very quickly to over-correct conditions to place the converter in a safe, idle mode; or to trip the output circuit breaker. Motor generators, being of 1930s design, are heavily overbuilt. These rugged machines can absorb large load transients and demanding fault conditions, while continuing to remain online. Their output waveform is also perfectly sinusoidal without noise or higher harmonic output. They can actually absorb harmonic noise produced by solid-state devices, effectively serving as a filter. These attributes, combined with their high fault-current capability, make them desirable in a stabilizing role within the power system. Amtrak has retained two of the original converter plants and plans to overhaul them and continue their operation indefinitely.

Disadvantages of motor generators include lower efficiency, generally between 83% (lightly loaded machine) and 92% (fully loaded machine). In comparison, cycloconverter efficiency can exceed 95%. Also, motor generators require more routine maintenance due their nature as rotating machines, given the bearings and slip rings. Today, the outright replacement of motor generators would also be difficult due to the high manufacturing cost and limited demand for these large 25 Hz machines.

• Metuchen, NJ – 25 MW Motor Generator. Upgrades to transmission lines and circuit breakers are planned for 2010.[6] 40.530743°N 74.347281°W / 40.530743; -74.347281 (Metuchen Rotary Frequency Converter)
• Lamokin (Chester), Pennsylvania – The Lamokin plant was built in the 1920s and has a net capacity of 48 MW and consists of three 16 MW motor generators. All three units will be overhauled, including re-winding of rotors and stators, and replacement of slip ring assemblies. Associated breakers and cables are also planned for replacement.[6] 39.843241°N 75.377225°W / 39.843241; -75.377225 (Lamokin Rotary Frequency Converter)

The static converters in the system were commissioned during the decade between 1992 and around 2002. Static converters use high-power solid-state electronics, with few moving parts. Chief advantages of static converters over motor generators include lower capital cost, lower operating costs, and higher conversion efficiency. The Jericho Park converter exceeds its efficiency design criteria of 95%. Major disadvantages of solid state converters include harmonic frequency generation on both the 25 Hz and 60 Hz sides, and lower overload capability.

• Sunnyside Yard (Long Island City), NY – Static Inverter rated at 30 MW ordered from ABB in 1993 for $27 million. This converter is operated by Amtrak and generally runs at low continuous loading to provide peaking and reactive power support to the New York area. 40.750499°N 73.921753°W / 40.750499; -73.921753 (Sunnyside Yard Static Converter)
• Richmond (Philadelphia), PA – The Richmond Static Converter plant consists of five 36 MW modules and has a net capacity of 180 MW. It was ordered from Siemens in 1999 for $60 million and installation was completed around 2002. The plant receives 69 kV, three phase, 60 Hz power from the PECO Energy Company. Although the exact electrical architecture of the converter modules is unknown, they are presumably of the DC link variety (Rectifier, filtering capacity, and inverter placed back to back) based on other Siemens traction power converters. The 2006 traction network shutdown originated in one of the converter modules at this plant. Richmond output power is scheduled with PECO, although the units themselves are operated by Amtrak remotely from Philadelphia. Generally, the three PECO-supplied converters (Richmond, Metuchen, and Lamokin) are scheduled as a block with PECO. 39°59′1″N 75°4′41″W
• Jericho Park, MD – 20 MW Static Converter. Jericho Park was constructed to replace the capacity lost when BG&E declined to renew the Benning rotary converter contract. BG&E proposed a static converter to replace Benning and Jericho Park came on service six years later. It consists of two 10 MW cycloconverter modules supplied by GE. 39°0′56″N 76°46′09″W
  Jericho Park was the first solid-state power supply introduced on the Amtrak network. It suffered from some filtering network problems caused by the highly distorted voltage present on the catenary and was ultimately downgraded from its original design capacity of 25 MW to 22 MVA.[7] Amtrak has requested funding to rehabilitate portions of the converter in an ARRA request.[6] During the twelve-month period that ended in August 2009, the Jericho Park converter used about 70 GWh of energy. Note that SEPTA's static converter plant at Wayne Junction is also based on this technology, although it was supplied by a different company; see SEPTA's 25 Hz Traction Power System. 39°0′56″N 76°46′9″W
• Metuchen – In October 2014 Amtrak placed a contract with Siemens for two 30 MW converters to supplement the existing 25MW motor-generator from 1933.[8] The project was completed in 2017 and forms part of the New Jersey High Speed Rail Improvement Program (NJHSRIP).

During the beginning of the 20th century, 25 Hz power was much more readily available from commercial electrical utilities. The vast majority of urban subway systems used 25 Hz power to supply their lineside rotary converters used to generate the DC voltage supplied to the trains. Since rotary converters work more efficiently with lower frequency supplies, 25 Hz was a common supply frequency for these machines. Rotary converters have been steadily replaced over the past 70 years with, at first, mercury arc rectifiers and more lately solid-state rectifiers. Thus, the need for special frequency power for urban traction has disappeared, along with the financial motivation for utilities to operate generators at these frequencies.

Long Island City Power Station in Hunter's Point, NY was built by the Pennsylvania Railroad in 1906 in preparation for the North River Tunnels and the opening of Pennsylvania Station in Manhattan. The station consisted of 64 coal-fired boilers and three steam turbine generators with a total capacity of 16 MW. In 1910, the station was expanded with two additional turbine generators for a total capacity of 32.5 MW. Power was transmitted to rotary converters (AC to DC machines) for use in the PRR's original third rail electrification scheme. Like most DC electric distribution systems of the time (Thomas Edison's being the most famous), 25 Hz power was used to drive rotary converters at substations along the line. Some sources state that the station was largely dormant by the 1920s.[9] When AC overhead electrification was extended in the 1930s, Long Island City connected to the 11 kV catenary distribution system.[11] Operation of the station was transferred to Consolidated Edison in 1938, although ConEd began supplying power from the adjacent Waterside Generating Station, most likely due to declining overall demand for 25 Hz power. The station was disused and sold in the mid-1950s. 40.7430°N 73.9581°W / 40.7430; -73.9581 (Long Island City Generating Station (Disused))

Originally constructed by Consolidated Edison to supply power to their DC distribution system in Manhattan, Waterside began supplying power to the PRR's AC system around 1938 when ConEd assumed operation of the Long Island City Station. The single-phase turbine generators were retired in the mid-1970s due to safety concerns. Two transformers were installed to supply catenary power from remaining (three-phase) portions of ConEd's still relatively extensive 25 Hz system. Power flow management problems prevented usage of this source under other than emergency conditions.[10] 40.7464°N 73.9707°W / 40.7464; -73.9707 (Waterside Generating Station (Demolished))

In 1986, Baltimore Gas and Electric elected to not renew the contract under which it had operated the Benning Power Station frequency changer on behalf of Amtrak. They proposed a static frequency changer which was built at Jericho Park (Bowie, Maryland) and placed on service in the spring of 1992.[12] 38.897534°N 76.959298°W / 38.897534; -76.959298 (Benning Frequency Changer ( demolished))

Although reactive power has primarily been supplied along with real power by the steam turbines and motor generators of the system, the PRR briefly used two synchronous condensers. Shortly after commissioning the 1915 electrification, the railroad discovered that the 44 kV feeders and large inductive loads on the system were causing significant voltage sag. The supplying electric utility (Philadelphia Electric) also discovered that power factor correction was needed. In 1917, the PRR installed two 11 kV, 4.5 MVA synchronous converters at Radnor, the approximate center point of the system load.[13] This substation was located at the site of water tanks used to supply water to track pans which supplied water to conventional steam locomotives. At some later time, the converters were shut down and removed. Dedicated machines for reactive power support have not been used subsequently by either the PRR or Amtrak. 40.044725°N 75.359463°W / 40.044725; -75.359463 (Radnor)

The Ivy City substation project marked the first extension of 138 kV transmission line since Safe Harbor Dam was constructed in 1938. In the original PRR electrification scheme, the 138 kV transmission lines went south from Landover to the Capital South substation rather than following the line through Ivy City to the northern approach to Union Station. The two tracks between Landover and Union Station had no high voltage transmission line above them; Union Station catenary was fed at 12 kV from the Landover and Capitol substations (the latter via the First Street Tunnels). When the Capitol South substation was abandoned, coincident with the de-electrification of the track between Landover and Potomac Yard, Union Station and its approaches became a single-end fed section of track. This combined with rising traffic levels resulted in low voltage conditions on the approaches to Union Station and decreased system reliability.[25]

The Ivy City project resulted in the installation of two 4.5 MVA transformers in a 138/12 kV substation on the northeast edge of the Ivy City yard complex and 5.2 miles (8.4 km) of 138 kV transmission line to augment the overstretched facilities at Landover. Since the original catenary supports along this section of track were only high enough for the 12 kV catenary wire, the 138 kV lines were installed on new steel monopod poles installed along the right-of-way. Except for the fact that the new poles only carry four conductors rather than the typical six for a utility line, the new line appears as a typical medium voltage power line rather than the typical PRR style H-shaped structure.

In 2011, Amtrak replaced the transmission lines that tie the Conestoga Substation to Parkesburg via Atglen. These lines were originally installed over the Atglen and Susquehanna Branch. The line was subsequently abandoned by Conrail and the tracks removed, but Amtrak has retained an easement to operate its 138 kV transmission lines over the roadbed. Towers and conductors and wire over 24 miles (39 km) of the route were replaced; work was completed in September 2011.[26] The scope of work included:

• Original portal and cantilever catenary support (~450 structures) removal.
• Installation of 257 new monopole structures.
• 96 miles (154 km) of ACSR transmission conductor installation (two circuits, two wires each).
• 24 miles (39 km) of fiberoptic ground line.

Funding for this project was included under the ARRA program. The specified number of poles, spaced approximately 500 feet (150 m) per tower, is approximately twice as far apart as the span length between the 1930s structures, which averaged 270 feet (82 m).[19]

In late 2010, Amtrak solicited design services for new transmission lines between Paoli and Zoo substations. Primary objectives of this expansion include improving reliability of transmission between Safe Harbor and Philadelphia, and reducing maintenance costs. This project complements the Safe Harbor to Atglen transmission line replacement, which has already been completed.

The Zoo to Paoli transmission line would replace the current supply scheme which uses 138 kV lines which run circuitously along the SEPTA Cynwyd Line, the Schuylkill Branch rail-trails and the Trenton Cut-off between the Zoo and Frazer substations. The new routing will reduce maintenance costs, as Amtrak must maintain transmission poles and control vegetation along right-of-way which it neither owns nor uses for revenue service. The conceptual line will run from the existing Paoli substation to the junction of the Harrisburg to Philadelphia main line and SEPTA's Cynwyd Line at 52nd Street in West Philadelphia. 39.9785°N 75.2280°W / 39.9785; -75.2280 (End of New Construction for Paoli-Zoo Transmission Lines).

The new lines would connect to the existing 1ED and 2ED circuits, which would be abandoned between the junction and their current terminus at the Earnest Junction HT Switch. The plan also includes construction of a 138/12 kV substation at Bryn Mawr to replace the existing switching station. The existing 1915 catenary structures are planned for replacement, and new transmission supports will be compatible with catenary replacement.[27] However, none of this was done due to local opposition.[28]

A new substation (Number 34A) called Hamilton was constructed in Mercer County, NJ. Work on the site began in early 2013, and the substation sap put into service in early 2015.

The Morton #01 and Lenni #02 substations are owned by SEPTA and supply the Media/Wawa Line; therefore, they are not covered by Amtrak capital funding programs. SEPTA's own capital improvement plan, formulated in late 2013 after passage of funding legislation in Pennsylvania, allowed for the renewal of all components at Morton and Lenni.[29][30]

In October 2014 SEPTA requested interested contractors to submit bids for the rehabilitation of Lenni substation.[31] In December 2014 SEPTA awarded a $6.82 million contract to Vanalt Electrical for the work.[32] The work was completed by the end of fall 2016.[33]

In February 2014 SEPTA awarded a $6.62 million contract to Philips Brothers Electrical Contractors Inc.[34] for the rehabilitation of Morton substation.[35] The work was completed by the end of fall 2016.[36]

On May 25, 2006, during restoration from maintenance on one of the Richmond inverter modules, a command to restore the module to full output capability was not executed. The system tolerated this reduced capacity for about 36 hours, during which time the problem went unnoticed. During rush hour the next morning (May 26), the overall capacity became overloaded:

• At 7:55 am, the two Jericho Park converter breakers tripped.
• Shortly after, the Sunnyside converter tripped.
• At 8:02 am, three of the Richmond converter modules breakers tripped. A fourth tripped shortly afterward. After the fourth Richmond breaker tripped, the system began to destabilize. Human operators recognized the impending system damage and manually tripped the remaining power supplies, shutting down the entire 25 Hz network.[37]

By 8:03 am, the entire 25 Hz system, stretching from Washington, D.C. to Queens, New York, was shut down. About 52,000 people were stranded on trains or otherwise affected. Two New Jersey Transit trains stranded under the Hudson River were retrieved by diesel locomotives. Restoration was hampered by policies which allowed the converter stations to operate unattended during rush hour periods.[38] The 25 Hz system was restored by a 'black start' using the Safe Harbor water turbines, and most service along the system returned to normal by mid-afternoon. Amtrak subsequently improved its system of maintaining 'rescue' diesel locomotives near the Hudson River tunnels.[39]

Low system voltage around New York City caused a halt of trains in and around the New York area at 8:45 am on Wednesday, December 23, 2009. Power was never fully lost, and full voltage was restored by 11:30 am. Amtrak stated that an electrical problem in North Bergen, New Jersey (near the western portal and the Union City substation) caused the problem, but did not further elaborate on the nature of the malfunction.[40]

Low system voltages beginning at 7:45 am on Tuesday, August 24, 2010, caused Amtrak to order an essentially system-wide stoppage of trains within the 25 Hz traction network. Slow-speed service was gradually restored, and the power problem was corrected by 9:00 am, although delays persisted the remainder of the morning.[41]

On October 29, 2012, Hurricane Sandy struck the northeast coast of the U.S. Augmented by a nor'easter, the storm surge from Sandy raced through the Hackensack Meadows, severely damaging (among other railroad infrastructure) Kearney Substation #41 and knocking it offline. This loss of electrical capacity forced Amtrak and New Jersey Transit to operate fewer trains, using modified weekend schedules. With assistance from the U.S. Army Corps of Engineers, the substation was isolated from floodwaters and then dewatered.[17] After testing the substation's components, the degree of damage was determined to be less than initially feared, and after further repairs, Kearney Substation came back on-line on Friday, November 16, allowing the immediate return of all Amtrak and gradual return of all NJ Transit electric trains into Penn Station through the dewatered North River Tunnels.[42]

Amtrak has since requested federal funding to upgrade Kearny substation so it is high enough to not be affected by flood water.[43]