Talk:Amtrak's 25 Hz traction power system

Royalton/Enola Branch Curcuits
From both on-site visits and pictures of the Amtrak Section 9 power dispatch board the 138Kv circuit on the Royalton Branch is out of service while the line on the Enola Branch that crosses the Cumberland Valley bridge is in service. The eastern circuit is cut at Columbia and clearly out of service on the A&S south of Columbia. The Enola branch line has the contacts closed at the Lemo field switch, while the Royalton circuit's contacts are open at the Roy substation. Do you have any uodated information that I don't know about? Sturmovik (talk) 15:43, 3 January 2011 (UTC)

That was based off of this picture of the 30th Street mimic board from early 1997. Looks like your photos were circa 2008, so I should change it back. Where's the power section 9 dispatch board at? Mcg410 (talk) 16:13, 3 January 2011 (UTC)


 * Section 9 is at Harrisburg and was recently changed from its original equipment to new computerized system I am in possession of 2 Gigs of photos of the original load dispatch display board and controls.  I'll have to check them again, but I am fairly certain that as of 2006-2008 the Royalton Branch was out of service (probably because it is cut at Columbia) and the Enola Branch lines were in service.Sturmovik (talk) 17:49, 3 January 2011 (UTC)


 * I checked my photos of the Harrisburg office and you were correct that the Royalton Line is the active one. However it seems to switch from the west circuit to the east circuit north of Columbia.  From the diagram it appears that the Rowenna Substation used to play a role in this.

Frequency Changer FC and Static Frequency Changer SFC
While we are all I here I’d like to propose adoption of these terms in place of M-G Set, Rotary Frequency Converter, Static Frequency Converter, Static Inverter or Static Cycloconverter.

I find M-G Set to be too general a term, applicable to other types of machines. Likewise for converter, although in trolley and 3rd rail Traction circles, Rotary Converter is the normal term for an AC-DC machine characterized by a shared rotor/armature. M-G sets can occasionally found in that service but then the term is deliberately used to bring out the distinctive differences of a separate rotor-armature machine.

Inverter is usually a Solid State DC-AC device and while Jericho’s Cycloconverter is a specific type of AC-AC device it was still referred to as an SFC outside of the station’s detailed technical papers.

My most basic reason is that Frequency Changer and SFC are the long running, well recognized Railroad and Utility terms for the equipment we are discussing and have been persistently used in the source documents we are drawing from.

Similarly Utilities usually refer to Water Turbines as Hydraulic Turbines.

Opinions? PhaseBreak (talk) 20:44, 4 January 2011 (UTC)


 * Sounds fine to me. I suggest retaining a discussion of specific type in the converter's description paragraph, but generic terms will probably be more clear everywhere else in the article. Mcg410 (talk) 17:39, 6 January 2011 (UTC)

Requested move

 * The following discussion is an archived discussion of the proposal. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section. 

No consensus to move as proposed. I believe that there is a consensus to change, but identifying the target is a problem. So discuss and if a solution is found this should be brought back for renaming. Vegaswikian (talk) 22:41, 23 February 2011 (UTC)

Amtrak's 25 Hz Traction Power System → Traction power along the Northeast and Keystone Corridors — First, these are not proper names. Second, the wording of the title implies that this is a proprietary system for Amtrak when it is not. We need to find a more generic name, or maybe merge to 25 Hz railway electrification in the United States? Feel free to propose to exactly what title these pages are to be moved to, the above titles are only to satisfy the bots. &mdash; Train2104 (talk • contribs • count) 00:01, 30 January 2011 (UTC)


 * SEPTA's 25 Hz Traction Power System → SEPTA Regional Rail traction power

The current article titles appear to describe two good topics very well. Agree that the capitalisation is wrong, and I wouldn't use the possessive, but that's all. A merge doesn't seem warranted, these are two good topics. It would be good to also have a higher level article on 25Hz traction power, which would include for example the now dismantled Newcastle, Australia tramway system and many others. Utility frequency seems to be all we have, or am I overlooking something?. Meantime for these specific articles, how about Amtrak 25 Hz Traction Power System and SEPTA 25 Hz Traction Power System? Andrewa (talk) 04:56, 30 January 2011 (UTC)

It’s a title, not a sentence, the rules of grammar don’t apply well. See the Wikipedia logo at the top left. The apostrophe “s” is possessive not proprietary, Amtrak is there as an adjective.
 * No Change

We don’t have all the sections of this encyclopedia written, so while many sections need broader umbrellas they doesn’t exist yet. This article particularly suits a reader searching from the real installation which in this case is more likely than someone coming from a general viewpoint. Also the work to make a generic article complete is not available. If it were to be contributed it would be large and probably use pointers to sub articles for each system. This would end up being one of those the sub articles so its name is fine as is.

If anything bothers me about the titles it’s their lack of mention of the Pennsylvania and Reading railroads. As much as the articles intend to be present day, the systems are inexorably tied to their history. They are at least as valuable for that history too. I do not however see “PRR 25 HZ” as an answer nor do I see any other answer that is better than what we’re going along with now. PhaseBreak (talk) 09:49, 31 January 2011 (UTC)
 * The above discussion is preserved as an archive of the proposal. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.

Suggestion -- Clarify Delair to Frankford circuits
I might offer a suggestion which may or may not increase the accuracy of the page a bit and satisfy a curiosity as the number of circuits from Richmond to Frankford seem to be more than just 2 and there only seems to be one circuit between Frankford Sub and Conwells Sub. The second circuit from Conwells (river side) goes right over to Richmond.

I was riding the Market Frankford Line and one gets a clear view of the Franford Junction area. One can see how four 138kv circuits seem to come over from Richmond and split up at Frankford right near the yard, two heading south (railroad west) by way of Franford Sub


 * These are the lines terminating in air switches 230W and 130W at Frankford.

and two heading north (railroad east),


 * These terminate at 230E and 130E at Cornwells.

one merging with a circuit between Frankford Sub and Cornwells Sub.


 * There is a three way transmission wire terminating at 22HT (Frankford), 22 (Frankford HT Switch), and 230E (Cornwells).

It looks like two of the four (the two circuits on the south side poles along the Delair Line) go right into Frankford Sub.

Of the remaining two which are on the north side poles:

It looks like one circuit bypasses Frankford Sub completely and turns 90 degrees north and goes up to Conwells Heights on the river side poles. The other circuit turns 90 degrees east but goes through the field switch and then joins the Frankford Sub to Conwells Heights Sub circuit east of the Frankford Sub, right near where the abandoned walkway to the yard still stands.

One can see the same arrangement if viewing the location from the parking lot behind where the new Lowe's on Aramingo Avenue is. When close to Frankford Sub, one can easily see only three 138kv circuits going into the substation from the east or north end: two over to Richmond and one along the side of the tracks opposite the river (Track #4 side) up to Cornwells.

Would the two circuits which head north or east both be backup feeders in case of damage to the poles carrying the two circuits along the abandoned ROW of the K&T Branch or did the PRR want to send four circuits north? Does this observation agree with the actual true prints and circuit layouts on paper?


 * I remember someone said once on a discussion board that this design preserved a limited ability to send power from North to South or vice versa along the main line in event of a catastrophic failure at Richmond or a derailment that damaged the transmission lines along the Delair or K&T lines. Don't remember who said that or where but it makes sense.Mcg410 (talk) 06:14, 27 May 2011 (UTC)

Thanks! Just curious. I appreciate any feedback. Chooch331 (talk) 22:28, 26 May 2011 (UTC)


 * Here's an excerpt of the Philadelphia mimic board. Mcg410 (talk) 05:57, 27 May 2011 (UTC)



Yes, this photograph confirms what I pieced together in the field. Six circuits out of Richmond. Two go up the K&T to Cornwells Sub, Two go to Frankford Sub and head south, One goes to Cornwells Sub by way of Delair Br and then mainline just north of Frankford Jct (on river side of main), the other enters FKD field switch and then connects to the single Fkd Sub to Cornwells Sub on other side of the main.

It would make sense, though not actually confirmed, that the single Cornwells Sub to Frankford Sub circuit which splits with a branch though the field switch and over to Richmond would allow emergency bypasses and feeds.

Chooch331 (talk) 15:23, 22 October 2011 (UTC)

One of the poles supporting the HT field switch outside of Frankford was taken out by train 188 in its May 12, 2015 accident. The switch was removed. PhaseBreak (talk) 08:51, 20 October 2019 (UTC)

Lamokin to Lenni Circuit
Not sure if some side details would be nice -- This circuit is on standard power poles like the four circuits out of Safe Harbor (e.g. non catenary). It loosely follows the Chester Creek Branch but at times deviates quite a bit from the ROW because the branch makes many odd and tight twists and turns. It's hard to follow the circuit on Bing "birds eye" because it disappears into the countryside quite a bit. It must be fun trying to keep it clear of trees and such.

In contrast, the fact that the K&T circuits out of Richmond tightly follow the ROW with PRR_style catenary poles has lead to much discussion and cussin' over whether or not the K&T was ever electrified but I never found any evidence that it ever was.

Chooch331 (talk) 15:23, 22 October 2011 (UTC)

March 19, 2011 blackout
On 3/19/11, the 25 Hz system had a failure that interrupted service on the Northeast Corridor for several hours. This is discussed at: http://www.railroad.net/forums/viewtopic.php?f=46&t=80530 I'm not sure if my link qualifies as a verifiable source per Wikipedia policy, and I don't know of a better source; but the article would be improved if it mentioned this incident. Oaklandguy (talk) 08:12, 6 September 2011 (UTC)
 * I don't think any one of the many power outages that the NEC has suffered is necessarily worth pointing out. But you're right about RR.net not meeting RS guidelines. oknazevad (talk) 21:48, 6 September 2011 (UTC)
 * SEPTA is currently fixing the catenary on the Manayunk-Norristown line, which was going on all summer. --Mfs1013 (talk) 21:51, 6 September 2011 (UTC)
 * There's also news articles mentioned in the thread, might it be worth including if we cited those? &mdash; Train2104 (talk • contribs • count) 23:49, 6 September 2011 (UTC)
 * Eh. As I said, and as Mfs1013 noted in his comparison to a far more prolonged outage (at least that's what I think he was getting at), a power outage of a few hours on a hundred year old system that has had many periodic outages in it's many decade long career isn't notable enough, I think. It appears to have had no lasting impact, and therefore isn't worth mentioning. oknazevad (talk) 04:57, 8 September 2011 (UTC)

Why low frequency ?
OK so alternating current (AC) is better than direct current (DC), because of the ability to operate at higher voltages  and therefore lower current, for a given power capacity. It is also easy to transform between high and low AC voltages,  which is hard to do with DC without modern high-power silicon devices.

But why low frequency ? What exactly is the point of that ? Whats wrong with 60 Hz AC power ? Eregli bob (talk) 10:15, 23 May 2012 (UTC)


 * It comes down to how electric motor control systems work. A DC motor rotational speed is a function of voltage and DC motors, which use brushes to transmit current to the rotating armature, are controlled by cutting in resistance in series with the motor.  AC motors motors tend to be of the induction type where rotation speed is a function of frequency.  In the early 20th century there was no practical way to create an AC inverter for fine motor control and AC locomotives with induction motors could only run at one of a few fixed speeds (often 10 and 20mph freight crawls, see PRR FF1).  However, there was a loophole in the form of an AC/DC Universal Motors, which is a brushed motor like AC that can also function with AC current, the lower frequency the better.  With an AC motor that could change its rotational speed based on voltage instead of frequency AC/DC electric locomotives became practical without the need for an AC/DC conversion.  The straight AC locomotive that the PRR favored made use of transformer tap changers in their propulsion system to get a variety of voltages from the 11Kv overhead line and that then resulted in fine grain speed control.  The GG-1, for example, used 22 throttle positions to allow the engineer to provide smooth acceleration.Sturmovik (talk) 11:23, 23 May 2012 (UTC)

The low frequency assists with motor commutation. It also reduces the level of inductive coupling to other circuits, such as telecommunications circuits. The lower frequency also reduces the inductive impedance of the overhead catenary system, which means that power can be transmitted further, or in higher amounts, before the voltage drop becomes unacceptable. Bhtpbank (talk) 14:08, 19 June 2013 (UTC)


 * The bias towards 60 Hz is a relatively recent development when it comes to the Northeast Corridor. 25 Hz was the most efficient back before the country standardized on 60 Hz.  This is why railroad power on the NEC south of New York is 25 Hz.  Indeed, the hydroelectric dam at Safe Harbor has two 25 Hz turbines that are dedicated for railroad power for both Amtrak and SEPTA that are also configured to provide 60 Hz through a motor-converter if the need arises.  --KJRehberg (talk) 04:06, 12 July 2013 (UTC)

Substation 42 (Hackensack)
Would this substation need to be modified or moved to accomodate the new Hudson Tunnels? And why is a straight tunnel alignment into the West Side Yard and PSNY with a vent structure near the Lincoln Tunnel in NJ not being pursued? Can someone help me out here? Thanks. 73.223.223.152 (talk) 09:46, 24 June 2024 (UTC)