The traction power network of

Amtrak The National Railroad Passenger Corporation, Trade name, doing business as Amtrak (; ), is the national Passenger train, passenger railroad company of the United States. It operates intercity rail service in 46 of the 48 contiguous United Stat ...

uses 25 Hz for the southern portion of the

Northeast Corridor The Northeast Corridor (NEC) is an electrified railroad line in the Northeast megalopolis of the United States. Owned primarily by Amtrak, it runs from Boston in the north to Washington, D.C., in the south, with major stops in Providence, Rhod ...

(NEC), the

Keystone Corridor The Keystone Corridor is a 349-mile (562 km) railroad corridor between Philadelphia and Pittsburgh, Pennsylvania, that consists of two rail lines: Amtrak and SEPTA's Philadelphia to Harrisburg Main Line, Philadelphia-to-Harrisburg main li ...

, and several branch lines between New York City and Washington D.C. The system was constructed by the

Pennsylvania Railroad The Pennsylvania Railroad ( reporting mark PRR), legal name as the Pennsylvania Railroad Company, also known as the "Pennsy," was an American Class I railroad that was established in 1846 and headquartered in Philadelphia, Pennsylvania. At its ...

between 1915 and 1938 before the North American power transmission grid was fully established. This is the reason the system uses 25 Hz, as opposed to 60 Hz, which became the standard frequency for

power transmission Power transmission is the movement of energy from its place of generation to a location where it is applied to perform useful Mechanical work, work. Power (physics), Power is defined formally as units of energy per unit time. In SI units: :\text ...

in North America. The system is also known as the Southend Electrification, in contrast to Amtrak's 60 Hz traction power system that runs between Boston and New Haven, which is known as the Northend Electrification system. In 1976, Amtrak inherited the system from

Penn Central The Penn Central Transportation Company, commonly abbreviated to Penn Central, was an American class I railroad that operated from 1968 to 1976. Penn Central combined three traditional corporate rivals, the Pennsylvania, New York Central and the ...

, the successor to the Pennsylvania Railroad, along with the rest of the NEC infrastructure. Only about half of the system's electrical capacity is used by Amtrak; the remainder is sold to the regional railroads that operate their trains along the corridor, including

NJ Transit New Jersey Transit Corporation, branded as NJ Transit or NJTransit and often shortened to NJT, is a state-owned public transportation system that serves the U.S. state of New Jersey and portions of the states of New York and Pennsylvania. I ...

SEPTA SEPTA, the Southeastern Pennsylvania Transportation Authority, is a regional public transportation authority that operates bus, rapid transit, commuter rail, light rail, and electric trolleybus services for nearly four million people througho ...

and MARC. The system powers of the NEC between New York City and Washington, D.C., the entire Keystone Corridor, a portion of NJ Transit's

North Jersey Coast Line The North Jersey Coast Line is a Commuter rail in North America, commuter rail line running from Rahway, New Jersey, Rahway to Bay Head, New Jersey, traversing through the Jersey Shore region. Operated by New Jersey Transit, the line is electr ...

(between the NEC and Matawan), along with the entirety of SEPTA's

Airport An airport is an aerodrome with extended facilities, mostly for commercial Aviation, air transport. They usually consist of a landing area, which comprises an aerially accessible open space including at least one operationally active surf ...

, Chestnut Hill West, Cynwyd, and Media/Wawa lines.

History

The

(PRR) began experimenting with electric traction in 1910, coincident with their completion of the trans-Hudson tunnels and

New York Penn Station Pennsylvania Station (also known as New York Penn Station or simply Penn Station) is the main intercity railroad station in New York City and the busiest transportation facility in the Western Hemisphere, serving more than 600,000 passengers ...

. These initial systems were low-voltage

direct current Direct current (DC) is one-directional electric current, flow of electric charge. An electrochemical cell is a prime example of DC power. Direct current may flow through a conductor (material), conductor such as a wire, but can also flow throug ...

(DC)

third rail A third rail, also known as a live rail, electric rail or conductor rail, is a method of providing electric power to a railway locomotive or train, through a semi-continuous rigid conductor placed alongside or between the rails of a track (r ...

systems. While they performed adequately for tunnel service, the PRR ultimately found it inadequate for long-distance, high-speed electrification. Other railroads had, by this time, experimented with low frequency (less than 60 Hz)

alternating current Alternating current (AC) is an electric current that periodically reverses direction and changes its magnitude continuously with time, in contrast to direct current (DC), which flows only in one direction. Alternating current is the form in w ...

(AC) systems. These low-frequency systems had the AC advantage of higher transmission voltages, reducing resistive losses over long distances, as well as the typically DC advantage of easy motor control as

universal motor The universal motor is a type of electric motor that can operate on either AC or DC power and uses an electromagnet as its stator to create its magnetic field. It is a commutated series-wound motor where the stator's field coils are connected ...

s could be employed with transformer

tap changer A tap changer is a mechanism in transformers that allows for variable turn ratios to be selected in distinct steps. This is done by connecting to a number of access points, known as taps along either the primary or secondary windings. Tap changer ...

control gear.

Pantograph A pantograph (, from their original use for copying writing) is a Linkage (mechanical), mechanical linkage connected in a manner based on parallelograms so that the movement of one pen, in tracing an image, produces identical movements in a se ...

contact with trolley wire is also more tolerant of high speeds and variations in

track geometry Track geometry is concerned with the properties and relations of points, lines, curves, and surfaces in the three-dimensional positioning of railroad Track (rail transport), track. The term is also applied to measurements used in design, construct ...

. The

New York, New Haven and Hartford Railroad The New York, New Haven and Hartford Railroad , commonly known as The Consolidated, or simply as the New Haven, was a railroad that operated principally in the New England region of the United States from 1872 to 1968. Founded by the merger of ...

had already electrified a portion of its Main Line in 1908 at 11 kV 25 Hz AC and this served as a template for the PRR, which installed its own trial main line electrification between

Philadelphia Philadelphia ( ), colloquially referred to as Philly, is the List of municipalities in Pennsylvania, most populous city in the U.S. state of Pennsylvania and the List of United States cities by population, sixth-most populous city in the Unit ...

and Paoli, Pennsylvania in 1915. Power was transmitted along the tops of the

catenary In physics and geometry, a catenary ( , ) is the curve that an idealized hanging chain or wire rope, cable assumes under its own weight when supported only at its ends in a uniform gravitational field. The catenary curve has a U-like shape, ...

supports using four

single phase In electrical engineering, single-phase electric power (abbreviated 1φ) is the distribution of alternating current electric power using a system in which all the voltages of the supply vary in unison. Single-phase distribution is used when load ...

, two wire 44 kV distribution circuits. Tests on the line using experimental electric locomotives such as the PRR FF1 revealed that the 44 kV distribution lines would be insufficient for heavier loads over longer distances. In the 1920s, the PRR decided to electrify major portions of its eastern rail network and, because a commercial

electric grid An electrical grid (or electricity network) is an interconnected network for electricity delivery from producers to consumers. Electrical grids consist of power stations, electrical substations to step voltage up or down, electric power tran ...

did not exist at the time, the railroad constructed its own distribution system to transmit power from generating sites to trains, possibly hundreds of miles distant. To accomplish this, the PRR implemented a pioneering system of single-phase

high voltage High voltage electricity refers to electrical potential large enough to cause injury or damage. In certain industries, ''high voltage'' refers to voltage above a certain threshold. Equipment and conductors that carry high voltage warrant sp ...

transmission lines In electrical engineering, a transmission line is a specialized cable or other structure designed to conduct electromagnetic waves in a contained manner. The term applies when the conductors are long enough that the wave nature of the transmis ...

at 132 kV, stepped down to the 11 kV at regularly spaced substations along the tracks. The first line to be electrified using this new system was between Philadelphia and

Wilmington, Delaware Wilmington is the List of municipalities in Delaware, most populous city in the U.S. state of Delaware. The city was built on the site of Fort Christina, the first Swedish colonization of the Americas, Swedish settlement in North America. It lie ...

in the late 1920s. By 1930, catenary extended from Philadelphia to

Trenton, New Jersey Trenton is the List of capitals in the United States, capital city of the U.S. state of New Jersey and the county seat of Mercer County, New Jersey, Mercer County. It was the federal capital, capital of the United States from November 1 until D ...

, by 1933 to New York City, and by 1935 south to

Washington, D.C. Washington, D.C., formally the District of Columbia and commonly known as Washington or D.C., is the capital city and federal district of the United States. The city is on the Potomac River, across from Virginia, and shares land borders with ...

Finally, in 1939, the main line from Paoli west to

Harrisburg Harrisburg ( ; ) is the List of capitals in the United States, capital city of the Commonwealth (U.S. state), U.S. commonwealth of Pennsylvania and the county seat, seat of Dauphin County, Pennsylvania, Dauphin County. With a population of 50, ...

was completed along with several freight-only lines. Also included were the Trenton Cutoff and the Port Road Branch. Superimposed on these electrified lines was an independent power grid delivering 25 Hz current from the point of generation to electric locomotives anywhere on nearly 500 route miles (800 km) of track, all under the control of electric power dispatchers in Harrisburg, Baltimore, Philadelphia and New York City. Northeast railroads atrophied in the years following

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

; the PRR was no exception. The infrastructure of the Northeast Corridor remained essentially unchanged through the series of mergers and bankruptcies, which ended in Amtrak's creation and acquisition of the former PRR lines, which came to be known as the Northeast Corridor. The circa 1976 Northeast Corridor Improvement Project had originally planned to convert the PRR's system to the utility grid standard of 60 Hz. Ultimately, this plan was shelved as economically unfeasible, and the electrical traction infrastructure was left largely unchanged with the exception of a general traction power voltage increase to 12 kV and a corresponding transmission voltage increase to 138 kV. During the 1970s, several of the original converter or power stations that originally supplied power to the system were shut down. Also, the end of electrified through-freight service on the Main Line to Paoli allowed the original 1915 substations and their 44 kV distribution lines to be decommissioned with that section of track being fed from 1930s-era substations on either end. Between 1992 and 2002, several static converter stations were commissioned to replace stations that had or were being shut down. Jericho Park, Richmond, and Sunnyside Yard converters were all installed during this period. This replaced much of the electrical frequency conversion equipment, but the lineside transmission and distribution equipment were unchanged. In 2003, Amtrak commenced a capital improvement plan that involved planned replacement of much of the lineside network, including 138/12 kV

transformer In electrical engineering, a transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple Electrical network, circuits. A varying current in any coil of the transformer produces ...

circuit breaker A circuit breaker is an electrical safety device designed to protect an Electrical network, electrical circuit from damage caused by current in excess of that which the equipment can safely carry (overcurrent). Its basic function is to interr ...

s, and catenary wire. Statistically, this capital improvement has resulted in significantly fewer delays, although dramatic system shutdowns have still occurred.

Specifications and statistics

The 25 Hz system was built by the Pennsylvania Railroad with a nominal voltage of 11 kV. The nominal operating voltages were raised in 1948 and are now:ET Electrical Operating Instructions (AMT-2) retrieved from http://www.amtrakengineer.net/AMT2111505.pdf on October 9, 2009. * Catenary (Traction) Voltage: 12 kV * Transmission Voltage: 138 kV * Signal Power: ** 2.2 kV 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 Hz – all electrification work from 1930 onward As of 1997, the system included of 138 kV transmission lines, 55 substations, 147 transformers, and of 12 kV catenary. Over 550 GWh of energy is 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 In electrical engineering, the power factor of an AC power system is defined as the ratio of the ''real power'' absorbed by the electrical load, load to the ''apparent power'' flowing in the circuit. Real power is the average of the instantaneou ...

varies between 0.75 and around 0.85.

Power sources

Electrical power originates at seven generation facilities or traction current converter plants. The

nameplate capacity Nameplate capacity, also known as the rated capacity, nominal capacity, installed capacity, maximum effect or gross capacity,Forczek 2009, p. 18. Peak load has risen significantly over time. In 1997, the peak load was 148 MW. Regardless of the source, all converter and generator plants supply power to the transmission system at 138 kV, 25 Hz,

single-phase In electrical engineering, single-phase electric power (abbreviated 1φ) is the distribution of alternating current electric power using a system in which all the voltages of the supply vary in unison. Single-phase distribution is used when loads ...

, using two wires. Typically, at least two separate 138 kV circuits follow each right of way to supply the line-side substations. Currently, the following converter and generating plants are operable, although all are rarely in operation simultaneously due to maintenance shutdowns and overhauls: Several types of equipment are currently in operation: static

inverter A power inverter, inverter, or invertor is a power electronic device or circuitry that changes direct current (DC) to alternating current (AC). The resulting AC frequency obtained depends on the particular device employed. Inverters do the op ...

motor–generator A motor–generator (an MG set) is a device for converting electrical power to another form. Motor–generator sets are used to convert frequency, voltage, or phase of power. They may also be used to isolate electrical loads from the elect ...

s (sometimes called rotary frequency converters),

water turbine A water turbine is a rotary machine that converts kinetic energy and potential energy of water into mechanical work. Water turbines were developed in the 19th century and were widely used for industrial power prior to electrical grids. Now, t ...

s (hydroelectric generators) and a static

cycloconverter A cycloconverter (CCV) or a cycloinverter converts a constant amplitude, constant frequency Alternating current, AC waveform to another AC waveform of a lower frequency by synthesizing the output waveform from segments of the AC supply without an ...

Hydroelectric generators

* Safe Harbor Dam, PA – The Safe Harbor Dam has two 28 MW

turbine A turbine ( or ) (from the Greek , ''tyrbē'', or Latin ''turbo'', meaning vortex) is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work. The work produced can be used for generating electrical ...

s 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 Parkesburg is a Borough (Pennsylvania), borough in Chester County, Pennsylvania, Chester County, Pennsylvania, United States. The population was counted as 3,866 at the 2020 United States census, 2020 census. The ZIP code is 19365. History Park ...

(two circuits), and

Perryville, Maryland Perryville is a town in Cecil County, Maryland, United States. The population was 4,361 at the 2010 United States Census, 2010 census. The town is located near an exit for Interstate 95 in Maryland, Interstate 95, on the north side of the outlet ...

(four circuits), where it is fed into the lineside 138 kV network. The 25 Hz turbines at the dam are scheduled by Amtrak but operated by Safe Harbor Water Power Company. Like other hydroelectric plants, it has excellent black start capability which was most recently demonstrated during a 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 were 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. 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 (rotary frequency converters)

Motor–generator A motor–generator (an MG set) is a device for converting electrical power to another form. Motor–generator sets are used to convert frequency, voltage, or phase of power. They may also be used to isolate electrical loads from the elect ...

s 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 A rotary converter is a type of electrical machine which acts as a mechanical rectifier, Power inverter, inverter or frequency converter. Rotary converters were used to convert alternating current (AC) to direct current (DC), or DC to AC power, ...

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

. 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 to 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. *Lamokin (

Chester Chester is a cathedral city in Cheshire, England, on the River Dee, Wales, River Dee, close to the England–Wales border. With a built-up area population of 92,760 in 2021, it is the most populous settlement in the borough of Cheshire West an ...

), 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.

Static inverters and cycloconverter

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 Long Island City (LIC) is a neighborhood within the New York City borough of Queens. It is bordered by Astoria to the north; the East River to the west; Sunnyside to the east; and Newtown Creek, which separates Queens from Greenpoint, Brook ...

), 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. * 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 Three-phase electric power (abbreviated 3ϕ) is a common type of alternating current (AC) used in electricity generation, Electric power transmission, transmission, and Electric power distribution, distribution. It is a type of polyphase system ...

, 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. * 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 into service six years later. It consists of two 10 MW

modules supplied by GE. 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. Amtrak has requested funding to rehabilitate portions of the converter in an ARRA request.Amtrak
"ARRA Project Summary FY2009."
/ref> During the twelve-month period that ended in August 2009, the Jericho Park converter used about 70 GWh of energy. 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. * Metuchen – In October 2014, Amtrak placed a contract with Siemens for two 30 MW converters to supplement the existing 25MW motor–generator from 1933. The project was completed in 2017 and forms part of the New Jersey High Speed Rail Improvement Program (NJHSRIP).

Former converter and power stations

The majority of power sources in the original Pennsylvania Railroad electrification were built prior to 1940. Some have been retired outright, others have been replaced with co-located static frequency converters, and others remain in service and will be refurbished and operated indefinitely. The following tables lists sources which are no longer in service: LongIslandCity

Declining need for 25 Hz power

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 A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction. The process is known as ''rectification'', since it "straightens" t ...

and, more recently, 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 Generating Station

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 Thomas Alva Edison (February11, 1847October18, 1931) was an American inventor and businessman. He developed many devices in fields such as electric power generation, mass communication, sound recording, and motion pictures. These inventions, ...

'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. When AC overhead electrification was extended in the 1930s, Long Island City connected to the 11 kV catenary distribution system. Operation of the station was transferred to

Consolidated Edison Consolidated Edison, Inc., commonly known as Con Edison (stylized as conEdison) or ConEd, is one of the largest investor-owned energy companies in the United States, with approximately $12 billion in annual revenues as of 2017, and over $62 ...

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.

Waterside Generating Station

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 the 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.

Benning frequency changer

In 1986, Baltimore Gas and Electric elected not to renew the contract under which it had operated the Benning Power Station

frequency changer A frequency changer or frequency converter is Electronics, electronic or electromechanical equipment that converts alternating current (Alternating current, AC) of one frequency to alternating current of another frequency. The equipment may also ...

on behalf of Amtrak. They proposed a static frequency changer, which was built at Jericho Park (

Bowie, Maryland Bowie () is a city in Prince George's County, Maryland, United States. Per the 2020 United States census, 2020 census, the population was 58,329. Bowie has grown from a small railroad stop to the largest municipality in Prince George's County; i ...

) and placed on service in the spring of 1992.

Radnor synchronous condenser

Although

reactive power In an electric circuit, instantaneous power is the time rate of flow of energy past a given point of the circuit. In alternating current circuits, energy storage elements such as inductors and capacitors may result in periodic reversals of the ...

has primarily been supplied along with real power by the steam turbines and motor–generators of the system, the PRR briefly used two

synchronous condenser In electrical engineering, a synchronous condenser (sometimes called a syncon, synchronous capacitor or synchronous compensator) is a DC-excited synchronous motor, whose shaft is not connected to anything but spins freely. Its purpose is not to c ...

s. 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

correction was needed. In 1917, the PRR installed two 11 kV, 4.5 MVA synchronous converters at , the approximate center point of the system load. 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.

Substations

The PRR's original 1915 electrification made use of four substations at Arsenal Bridge,

West Philadelphia West Philadelphia, nicknamed West Philly, is a section of the city of Philadelphia. Although there are no officially defined boundaries, it is generally considered to reach from the western shore of the Schuylkill River, to City Avenue to the n ...

, Bryn Mawr, and Paoli. The Arsenal Bridge substation stepped-up 13.2 kV, 25 Hz power supplied from PECO's Schuylkill power station on Christian Street to 44 kV for distribution. The remaining three substations reduced the 44 kV distribution voltage to 11 kV catenary voltage. The substations were operated from adjacent signal towers. They used typical period concrete buildings to house the transformers and switchgear while the line terminals were on the roof. From 1918 onward, outdoor stations were used, and when the main line electrification began in 1928, the stations became large open-air structures using lattice steel frameworks to mount the 132 kV terminations and

switchgear In an electric power system, a switchgear is composed of electrical disconnect switches, fuses or circuit breakers used to control, protect and isolate electrical equipment. Switchgear is used both to de-energize equipment to allow work to ...

. By 1935, new stations were connected to remote supervision systems, allowing power directors to open and close switches and breakers from central offices without having to go through the tower operators. Today, about 55 substations are part of Amtrak's network. Substations are spaced on average apart and feed 12 kV catenary circuits in both directions along the line. Thus, the catenary is segmented (via section breaks, also called 'sectionalizations' by the PRR) at each substation, and each substation feeds both sides of a catenary's section break. A train traveling between two substations draws power through both transformers. A typical substation includes two to four 138/12 kV transformers, 138 kV air switches that permit isolation of individual transformers, shutdown of one of the two 138 kV feeders, or cross-connection from one feeder to another. The output of the transformers is routed to the catenary via 12 kV circuit breakers and air disconnect switches. Cross-connect switches allow one transformer to feed all catenary lines. The PRR substation architecture was based on a long-distance, high-speed railway. The substation spacing ensures that any train is never more than from the nearest substation, which minimizes voltage drop. One disadvantage to the substation design as originally built by the PRR concerns its lack of 138 kV circuit breakers. Essentially, all segmentation of the 138 kV system must be manually accomplished, making rapid isolation of a fault on the 138 kV line difficult. Faults in one part of the line also affect the entire distribution system since it is impossible for the 138 kV transmission system to protect or reconfigure itself during a fault condition. High voltage faults generally are cleared by opening converter output breakers, which causes a concurrent loss of the converter. The system does not degrade gracefully under high-voltage faults. Rather than isolating, for example, the south 138 kV feeder between Washington and Perryville, the system would require opening converter output breakers at Jericho Park and Safe Harbor. This results in the loss of much more of the network than is required to simply isolate the fault.

Transmission lines

All transmission lines within the 25 Hz system are two-wire, single-phase, 138 kV. The center tap of each 138 kV/12 kV transformer is connected to ground; thus the two transmission lines are tied to ±69 kV with respect to ground and 138 kV relative to each other. Generally, two separate two-wire circuits travel along the rail line between substations. One circuit is mounted at the top of the catenary poles on one side of the track; the second circuit runs along the other side. The arrangement of catenary supports and transmission wires gives the overhead structure along former Pennsylvania Railroad lines its characteristic -tall H-shaped structure. They are much taller than the overhead electrification structures on other electrified American railroads due to the 138 kV transmission lines. Catenary towers and transmission lines along former

lines and Amtrak's New England division are much shorter and are recognizable due to different design and construction. While a majority of the transmission infrastructure is located directly above the rail lines on the same structure that supports the catenary system, some lines are either located above lines that have been de-electrified or abandoned or, in a few cases, on completely independent rights of way. The following is a list of all major segments of the 25 Hz 138 kV transmission infrastructure listing substations (SS or Sub) or high-tension switching stations (HT Sw'g) as termini. For clarity, the positions of substations are not repeated in this table. A listing of the high-tension switching stations follows.

Recent developments

Amtrak's capital improvement program which began in 2003 has continued to the present day and has since 2009 received added support from economic stimulus funding sources (American Recovery and Reinvestment Act of 2009 or ARRA). Major improvements in 2010 included: * Completion of the Ivy City substation and 138 kV transmission line. * Replace five traction power transformers. * Renew of catenary in Maryland. * Renew of catenary in Pennsylvania. * Continue catenary renewal along Hell Gate Line in New York. * Replace the 138 kV transmission line between Safe Harbor (Conestoga Substation) and Atglen, PA (just west of Parkesburg, PA). Major improvements planned for the future include: * Upgrade the Metuchen frequency converter. * Construction of a new substation, called Hamilton (Sub 34A), between Morrisville and Princeton. * Upgrade of the catenary and power system for high-speed operation in New Jersey.

Ivy City substation project

The Ivy City substation project marked the first extension of 138 kV transmission line since the 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 A union station, union terminal, joint station, or joint-use station is a railway station at which the tracks and facilities are shared by two or more separate railway company, railway companies, allowing passengers to connect conveniently bet ...

. 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. 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 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.

Conestoga to Atglen transmission line

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 of the route were replaced; work was completed in September 2011. The scope of work included: * Original portal and cantilever catenary support (~450 structures) removal. * Installation of 257 new monopole structures. * of ACSR transmission conductor installation (two circuits, two wires each). * of fiberoptic ground line. Funding for this project was included under the ARRA program. The specified number of poles spaced approximately per tower is approximately twice as far apart as the span length between the 1930s structures, which averaged .

Zoo to Paoli transmission line

In late 2010, Amtrak solicited design services for new transmission lines between Paoli and Zoo substations. Primary objectives of this expansion include improving the 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 that 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 the 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. . 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 the 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. However, none of this was done due to local opposition.

Hamilton substation project

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.

Morton and Lenni

The Morton #01 and Lenni #02 substations are owned by

and supply the

Media/Wawa Line The Media/Wawa Line is a SEPTA Regional Rail service that runs from Center City, Philadelphia, Center City Philadelphia west to Wawa Station, Wawa in Delaware County, Pennsylvania, Delaware County. It uses the West Chester Branch, which connects ...

; 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 Pennsylvania, officially the Commonwealth of Pennsylvania, is a U.S. state, state spanning the Mid-Atlantic (United States), Mid-Atlantic, Northeastern United States, Northeastern, Appalachian, and Great Lakes region, Great Lakes regions o ...

, allowed for the renewal of all components at Morton and Lenni.

Lenni

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

Morton

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

Recent problems

Despite the recent capital improvements throughout the system, several high-profile power failures have occurred along the NEC in recent years.

May 26, 2006, Blackout

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. 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. The restoration was hampered by policies that allowed the converter stations to operate unattended during rush hour periods. The 25 Hz system was restored by a ' black start' using the Safe Harbor water turbines, and most services along the system returned to normal by mid-afternoon. Amtrak subsequently improved its system of maintaining 'rescue' diesel locomotives near the Hudson River tunnels.

December 23, 2009, Brownout

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.

August 24, 2010, Brownout

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.

October–November 2012: Hurricane Sandy

On October 29, 2012,

Hurricane Sandy Hurricane Sandy (unofficially referred to as Superstorm Sandy) was an extremely large and devastating tropical cyclone which ravaged the Caribbean and the coastal Mid-Atlantic (United States), Mid-Atlantic region of the United States in late ...

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 United States Army Corps of Engineers (USACE) is the military engineering branch of the United States Army. A direct reporting unit (DRU), it has three primary mission areas: Engineer Regiment, military construction, and civil wor ...

, the substation was isolated from floodwaters and then dewatered. 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. Amtrak has since requested federal funding to upgrade the Kearny substation so it is high enough not to be affected by flood water.

Notes

Footnotes

References

* * * * * Retrieved from Google Books * "The Electrification of the Pennsylvania Railroad from Broad Street Terminal Philadelphia to Paoli", ''The Electric Journal'', Vol 12, pp. 536–541, Pittsburgh, PA: 1915. Retrieved fro
Google Books
November 10, 2010. * * . A good general overview of the 1930s electrification, written while most of the main line was complete, but work was still ongoing. * * Provides a good discussion on the design decisions related to the Ivy City substation. Good plan view of the substation and breaker and transmission line designations. * * Reply Testimony of Stanley R. Forczek, August 28, 2009. Case Number 9173
Retrieved
August 15, 2010. * Retrieved from Google Books on November 12, 2010. * * "Pennsylvania Station, New York Terminal Service Plant, 250 West Thirty-first Street, New York, New York, NY", ''Historic American Buildings Survey'', Survey Number HABS NY,31-NEYO,78A-, retrieved from th
Library of Congress
September 1, 2011. * * * New York Edison Company, Powerhouse, 686-700 First Avenue, New York, New York, NY, ''Historic American Buildings Survey'', Survey HABS NY,31-NEYO,159A-, retrieved from th
Library of Congress
on January 31, 2011. * {{Amtrak 25 Electric power distribution Electric power transmission systems in the United States Electric railways in the United States Railway electrification in the United States Traction power networks