SEPTA's 25 Hz traction power system

File:SEPTA Lansdale-wire-anchor.jpg. {{nowrap|24 kV}} (top) feeders are directed into the substation and {{nowrap|12 kV}} feeders (bottom) return to the catenary.]]

The Reading Company electrified its lines between Reading Terminal in Philadelphia, Pennsylvania, and Norristown, Doylestown, Chestnut Hill, Hatboro and West Trenton in 1931. The electrification was extended to include the Fox Chase Line in September 1966. Electrification was again extended from Hatboro to Warminster in the early 1970s.{{sfnp|Kneschke|Hong|Natarajan|Naqvi| 1995}}{{page needed|date=April 2022}}

The Reading's system used catenary electrified at {{nowrap|12 kV 25 Hz}} like the competing Pennsylvania Railroad's 1915 initial electrification and 1930s mainline expansion. Unlike the PRR's system, which included multiple power sources and an extensive high-voltage transmission network, the Reading's electrification was supplied solely by the rotary converter station at Wayne Junction. Although ownership and operation of the system has changed, the system has remained essentially unchanged with the exception of the replacement of the rotary converter station at Wayne Junction with a solid-state cycloconverter in 1986.

The Reading electrification system was designed for suburban MU operations and did not have to support the main line passenger or through freight operations of the rival Pennsylvania Railroad. While a complex system of high-voltage transmission lines was not necessary, the system was large enough to require the use of distribution feeders from the {{nowrap|25 Hz}} power supply at Wayne Junction. The feeders were set at {{nowrap|24 kV}}, double the traction voltage. Most of the rail lines would carry one or two feeders attached to the top of the catenary support masts. These {{nowrap|24 kV}} substation feeders can be distinguished from {{nowrap|12 kV}} traction feeders by the use of four-segment insulators as opposed to three-segment ones.

File:SEPTA Autotransformer.svg

The {{nowrap|24 kV}} lines feed a network of 11 substations (12 including the Wayne Junction switchyard) located every {{convert|8|to|10|mi}} along the electrified rail lines. Most branches are short enough to only require a single substation near the end of the line, but the Main and West Trenton lines are long enough to require intermediate substations. At each substation the {{nowrap|24 kV}} feeders are fed through autotransformers to be reduced to the traction voltage of {{nowrap|12 kV}}, which is then passed through circuit breakers before being fed into the overhead catenary wires.

Power is transmitted, effectively, at {{nowrap|36 kV}} because the {{nowrap|24 kV}} and {{nowrap|12 kV}} components are 180° out of phase. This design has several advantages over the PRR's more traditional transmission and distribution scheme. The highest voltage, with respect to ground, within the system is {{nowrap|24 kV}}. This is significantly less than the 69 kV seen in the PRR's system, which required much larger {{convert|80|ft}} towers and larger insulators and transformers. On a small system such as the Reading's, transmission infrastructure of this scale was unnecessary. Secondly, the system uses the {{nowrap|12 kV}} catenary wire for both transmission and distribution. This dual use of the catenary wire allows performing both functions with only two wires. The PRR's system in contrast required three wires: two for the single phase {{nowrap|138 kV}} transmission component and one for the {{nowrap|12 kV}} catenary feeder. In both systems, the rail is used as a return path for traction current.

File:SEPTA Lansdale-Substation-transformers-close.jpg.]]

All {{nowrap|25 Hz}} power on the ex-Reading system is generated at the Wayne Junction static converter plant. This plant was built between 1985 and 1990 and consists of three {{nowrap|15 MVA}} solid-state, cycloconverter-based modules. The system was built by ASEA and is similar technically to the converter later installed at Amtrak's Jericho Park converter.

The inverters replaced two ca. 1928 Westinghouse Electric motor generators that were each rated at {{nowrap|21.4 MVA}}. The capability also formerly existed to supply power from PECO Energy's Somerset Substation, which had three motor-generators normally used to supply the Pennsylvania Railroad's electrification system. This capability has been removed, as have the Somerset motor-generators. The ex-Reading system now operates completely independently from Amtrak's power system.

Wayne Junction receives {{nowrap|230 kV 60 Hz}} power from two redundant lines that connect to PECO substations at Waneeta, Tabor and Pulaski. Two {{nowrap|60 MVA 230/13.2 kV}} transformers reduce voltage for the static frequency converters. Cross-ties allow removing portions of the supply system from service for maintenance.

In March 2015 a contract worth $4,656,321 was awarded to STV Incorporated, for the provision of architectural and engineering services for the rehabilitation of static frequency converters at Wayne Junction, with services to be performed over a period of 60 months scheduled to commence in April 2015 (per Proposal No. 14-233-JHC).{{cite web |last=SEPTA |url=http://www4.septa.org/about/board/pdf/minutes%203-15.pdf |title=Minutes of Regular Board Meeting (March 2015) |website=SEPTA Board - Meeting Minutes |date=March 26, 2015 |access-date=5 August 2015}}

{{Reading Company substations}}

{{GeoGroup}}

Each of the former Reading Railroad substations was equipped with transformers and circuit breakers from American Brown Boveri. Most transformers are rated to supply about {{nowrap|2 MVA}} of power each (a few {{nowrap|4 MVA}} transformers exist). Each substation also contained a number of oil-filled circuit breakers to disconnect both the {{nowrap|12 kV}} and {{nowrap|24 kV}} lines under load. The larger substations also have a small equipment and maintenance building to house any control equipment or secondary transformers for generating the {{nowrap|100 Hz}} signal power.

Due to the robustness and simplicity of the components, until 2010 all the SEPTA substations were equipped with their original equipment, then approaching 80 years in service.

Callowhill substation was the first targeted for replacement, to eliminate the need to maintain the overhead wires over the abandoned Reading Viaduct rail line as feeders to the active tracks. Its replacement, Fairmount substation, was commissioned in the 3rd quarter of 2010,{{cite web|title=Regional Rail Substation Improvements|url=http://www.septa.org/reports/pdf/capbudget10.pdf|work=SEPTA Fiscal Year 2010 Capital Budget & Fiscal Years 2010-2021 Capital Program|publisher=SEPTA|access-date=5 September 2012|url-status=dead|archive-url=https://web.archive.org/web/20130211120909/http://septa.org/reports/pdf/capbudget10.pdf|archive-date=11 February 2013}} featuring two {{nowrap|12/24 kV 25 Hz}}, single-phase {{nowrap|5 MVA}} autotransformers as well as trolley breakers and other switchgear.{{cite web|title=Fairmount Substation and 30th Street Switching Station|url=http://www.gftransitrail.com/projects/fairmountsubstation.htm|publisher=Gannett Fleming Transit & Rail Systems|access-date=5 September 2012}}

Norristown substation received new transformers, trolley breakers, feeders, substation switchgear, protective relaying and a structural overhaul in a stimulus project.{{cite web|title=Norristown Power Substation Overhaul P2-2A|url=http://www.septa.org/stimulus/projects/rail/nor/p2-2a/index.shtml|work=SEPTA Stimulus Project Information|publisher=SEPTA|access-date=5 September 2012}}

In July 2012, the US Department of Transportation awarded SEPTA a $12.8 million Tiger IV grant to help refurbish Wayne Junction Substation.{{cite web| url=http://www.septa.org/service/rail/wayne-junction-update.html|website=www.SEPTA.org |publisher= Southeastern Pennsylvania Transportation Authority |title=Wayne Junction Substation Update}} In the words of SEPTA General Manager Joseph M. Casey, "We intend to use these resources to replace equipment that should be on display in a museum of transit history."

The grant was announced at ceremony at the substation which was attended by Transportation Secretary Ray LaHood, who said "It's not the sexiest, it's not the prettiest, but it's one of the most important projects."{{cite web|first=Amy Z. |last=Quinn | url=http://www.newsworks.org/index.php/component/flexicontent/item/41297-wayne-junction-announcement&Itemid=18|title=Unsexy, but critically needed, replacement coming for Wayne Junction Substation |website=www.newsworks.org|date=July 11, 2012 |access-date=5 August 2015}}

Renewal of Wayne Junction's three static frequency converters is expected to occur during the 2010s, in three stages in order to maintain redundancy. A fourth converter is to be added for system security.{{cite web|last=SEPTA| url=http://septa.org/rebuilding/substation/wayne-junction.html| title=Wayne Junction Static Frequency Converters (Main Regional Rail Line) |website=Rebuilding for the Future (Substation Program)| publisher=Southeastern Pennsylvania Transportation Authority| access-date=5 August 2015}}

In October 2014 SEPTA requested interested contractors to submit bids for the rehabilitation of the static frequency converters at Wayne Junction.{{cite web | url=http://www.septa.org/business/bid/100k/detail/14-223-JHC.html | title=Bids | Page | SEPTA }}

In September 2014 SEPTA requested interested contractors to submit bids for the rehabilitation of Ambler substation.{{cite web | url=http://www.septa.org/business/bid/100k/detail/14-156-JAB.html | title=Bids | Page | SEPTA }} In October 2014 SEPTA awarded a $7.99 million contract to Carr & Duff, Inc.{{cite web| url=http://www.carrduff.com| website=Carr & Duff|title=Carr and Duff, Inc.}} for the work.{{Cite web | title=Southeastern Pennsylvania Transportation Authority {{!}} Serving Bucks, Chester, Delaware, Montgomery, and Philadelphia counties | url=http://www.septa.org/business/bid/results/detail/pdf/r14-156-JAB.pdf | access-date=2025-01-04 | website=www.septa.org}}

On October 31, 2016, one of the substation's two main transformers burned out, and was replaced ahead of schedule a week later with one of the new transformers already on hand for the substation renewals at both Lansdale and Ambler.{{cite web|last1=Almeida|first1=John P.|title=SEPTA Lansdale Parking Garage Lansdale PA November 19 2016 [6th photo and caption]|url=http://www.trainweb.org/phillynrhs/RPOTW161120.html|website=Railfan Pictures of the Week|publisher=The Philadelphia Chapter of the National Railway Historical Society|access-date=30 November 2016|date=November 20, 2016}}

In the 1990s a fire at the Doylestown substation rendered it inoperable. Until the substation was repaired in 2013, the Doylestown Branch east of Lansdale had to be powered exclusively from the Lansdale substation. This "single-end feeding" of a {{convert|10|mi|adj=on}} section of track limited the number of MUs that could run simultaneously on the branch and also limited their maximum speed and acceleration.

The substation received a new 12/24 kV autotransformer in April 2015.{{cite web|last1=Almeida|first1=John P.|title=Out with the old: SEPTA transformer replacement Doylestown PA April 12 2015|url=http://www.trainweb.org/phillynrhs/RPOTW150621.html|website=Railfan Pictures of the Week|publisher=The Philadelphia Chapter of the National Railway Historical Society|access-date=29 June 2015|date=June 21, 2015}}

With the passage of a source of dedicated transportation funding by the Commonwealth of Pennsylvania, SEPTA announced in December 2013 a capital budget plan that includes renewal or replacement of all remaining former Reading substations, in five phases. The first phase involves replacement of Jenkintown substation and the renewal of Ambler substation's active components, projects for which final design had been completed by the end of 2013.{{cite web|last=SEPTA|title=Railroad Substation Program|url=http://www.septa.org/media/releases/2013/2013-12-19-capital-improvement-plan.pdf|work=Proposed Capital Plan: "Catching Up"|publisher=Southeastern Pennsylvania Transportation Authority|access-date=31 December 2013}}{{cite web|title=SEPTA Projects Funded Under Senate Bill 1|url=http://www.dotdecade.pa.gov/doi/pdf/SEPTA-Senate-Plan.pdf|work=PennDOT Decade of Investment|publisher=Pennsylvania Department of Transportation|access-date=31 December 2013|archive-date=31 December 2013|archive-url=https://web.archive.org/web/20131231225601/http://www.dotdecade.pa.gov/doi/pdf/SEPTA-Senate-Plan.pdf|url-status=dead}}

In November 2014 SEPTA requested interested contractors to submit bids for the rehabilitation of four substations (Lansdale, Bethayres, Chestnut Hill East and Hatboro).{{cite web |url=http://www.septa.org/business/bid/100k/detail/14-268-JHC.html|last=SEPTA| website=www.SEPTA.org|title=A&E Services for Rehabilitation of Regional Railroad Division Substations (Proposal Number 14-268-JHC)|date=November 2014|access-date=5 August 2015}} The engineering design work is expected to take two years, and the construction a further three years.

SEPTA also plans to build a new substation near Woodbourne station by Fall 2020, as the distance between Neshaminy Falls and Yardley substations is nearly twice the optimal {{convert|5|mi|adj=on}} distance between substations on a 12 kV 25 Hz system.{{cite web|last=SEPTA|title=Woodbourne Substation (West Trenton Line)| url=http://septa.org/rebuilding/substation/woodbourne.html|website=Rebuilding for the Future|publisher=Southeastern Pennsylvania Transportation Authority|access-date=29 June 2015}}

• Railway electrification system
• Amtrak's 25 Hz traction power system

{{Reflist|2}}

{{Reflist|2|group=S}}

• {{cite journal

| last = Doub

| first = C.L.

| title = Power Supply Facilities for Reading Suburban Electrification

| journal = Transactions of the American Institute of Electrical Engineers

| date = March 1931

| volume = 50

| issue = 1

| pages = 240–245

| issn = 0096-3860

| doi = 10.1109/T-AIEE.1931.5055770

| s2cid = 51646983

}}

• {{cite journal

| last = Kneschke

| first = Tristan A.

| title = Static Frequency Converter for SEPTA's Wayne Junction Traction Substation

| journal = IEEE Transactions on Industry Applications

| date = March 1985

| volume = IA-21

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| pages = 295–300

| issn = 0093-9994

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| s2cid = 17134542

}}

• {{cite book

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| title = ASME/IEEE Joint Conference on Railroads

| chapter = Introduction of static frequency converters on SEPTA's 25 Hz commuter rail system

| date = Apr 1990

| pages = 149–155

| doi = 10.1109/RRCON.1990.171673

| s2cid = 111289944

}}

• {{cite book

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| title = Proceedings of IEEE/ASME Joint Railroad Conference

| chapter = Load flow study and conceptual system design of SEPTA's regional rail division traction power system

| date = Mar 1994

| pages = 81–95

| isbn = 978-0-7803-1890-8

| doi = 10.1109/RRCON.1994.289017

| s2cid = 109631300

}}

• {{cite book

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| title = Proceedings of the 1995 IEEE/ASME Joint Railroad Conference

| chapter = Impedance calculations for SEPTA's rail power distribution system

| date = Apr 1995

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| isbn = 978-0-7803-2556-2

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| s2cid = 110918186

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• {{cite book

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| title = Proceedings of the 1997 IEEE/ASME Joint Railroad Conference

| chapter = Upgrade of SEPTA's regional rail power system

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| isbn = 978-0-7803-3854-8

| doi = 10.1109/RRCON.1997.581350

| s2cid = 109984985

}}

Category:SEPTA Regional Rail

Category:Rail infrastructure in Pennsylvania

Category:Rail infrastructure in New Jersey

Category:Electric railways in the United States

Category:Electric railways in Pennsylvania

Category:Electric railways in New Jersey

Category:Electric power distribution

Category:Reading Company

Category:Electric power transmission systems in the United States

Category:Traction power networks

Category:Railway electrification in the United States