As an electronics professional in my working days, I am always intersted in circuits. I was looking at a photo of Washington Union Station tracks with catenary all over the place. I realize the power all comes from one source. But in general in a setting like that, are all the wires essentially wired together, one big criss-cross grid? Or does each track have its own branch circuit? I am sure there are breakers cordoning it off into sections. So for example on a two track main, would the two stripes of wire be on separate breakers? Or would it be just one for the pair. Any other considerations I haven't thought of?
Guess any electrified RR can shut off power to one track while running trains on the other tracks? To allow work on the catenary, if nothing else?
I think one of the frequent posters has some hands-on experience with this matter, but I believe there is a NEC ex-PRR power control room, probably within the 30th Street, Philadelphia complex, or at Zoo or N. Phila., with essentially a wire-and-track map of the entire system from New Rochelle to Harrisburg and the current end of wire in the tunnel south of Union Station. Insulation breaks are shown, each section has its own push-to-cut-power button (and possibly push a second time to restore) and some lights to give a report on conditions. Metro-North-Connecticut-DOT has its own, and probably Amtrak New Haven - Boston is another. Before my move to Israel, Sunnyside - New Rochelle was controlled in the same room as Woodlawn - New Haven, but I am pretty certain that is now controlled in the same room as Sunnyside -Harrisburg and Washington.
Individual tracks in each station can be switched on and off, and ditto each track in each section in multi-track RoW.
But I expect to be corrected in one detail matter or another. Like my false memory of New Haven 6-10 sleepers. Rode them over a hundred times too. But they were not 6-10s.
I should also point out that the power room has control circuits, not the actual power. Power is fed from the substations spaced along the line with on-off relays controlled from the power room.
daveklepper I should also point out that the power room has control circuits, not the actual power. Power is fed from the substations spaced along the line with on-off relays controlled from the power room.
Any one know the various steps to verify the power is off and stays off ? The old PRR equipment certainly would make one very cautious that power is off and stays off. Wonder if any equipment will be replaced ?
The NEC is single phase, but the power supply is presumably 3 phase. I am guessing that the 3 phases are distributed to different tracks to try to even out power usage.
MidlandMike The NEC is single phase, but the power supply is presumably 3 phase. I am guessing that the 3 phases are distributed to different tracks to try to even out power usage.
Nope. PRR power supply is actually single phase. Note power lines are in pairs. Power is just like what comes into your home. Feeders to ground are 180 degrees out of phase so voltage feeder to feeder is twice that of feeder to ground.
Safe harbor generators provide this unique high voltage power. If comercial 3 phase power is used at power stations then. Phase balancing is actually done with motor generators called rotary converters in PRR dictionary. Or done electronically at the new Siemens power station being built in NJ. Also there are some phase balancing transformers.
blue streak 1 MidlandMike The NEC is single phase, but the power supply is presumably 3 phase. I am guessing that the 3 phases are distributed to different tracks to try to even out power usage. Nope. PRR power supply is actually single phase. Note power lines are in pairs. Power is just like what comes into your home. Feeders to ground are 180 degrees out of phase so voltage feeder to feeder is twice that of feeder to ground. Safe harbor generators provide this unique high voltage power. If comercial 3 phase power is used at power stations then. Phase balancing is actually done with motor generators called rotary converters in PRR dictionary. Or done electronically at the new Siemens power station being built in NJ. Also there are some phase balancing transformers.
Does mean that the rotary converters convert 60 Hz 3 phase directly to 25 Hz single phase?
MidlandMikeDoes mean that the rotary converters convert 60 Hz 3 phase directly to 25 Hz single phase?
Actually, I believe they might just do that. Either by how they are wired, or via gear reduction...
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
MidlandMike Does mean that the rotary converters convert 60 Hz 3 phase directly to 25 Hz single phase?
Lots of woodworkers use rotary converters to create three phase power at their home work shops that are fed by single phase power.
https://www.americanrotary.com/
Here is the start of a recent two-part IEEE article on the history of rotary converters.
Thanks RME!!
Part II
http://magazine.ieee-pes.org/novemberdecember-2013/history-10/
rdamon Thanks RME!! Part II http://magazine.ieee-pes.org/novemberdecember-2013/history-10/
rdamon Lots of woodworkers use rotary converters to create three phase power at their home work shops that are fed by single phase power. https://www.americanrotary.com/
These were traditionally called phase converters, essentially being a free running three phase synchronous or induction motor with the single phase input connected across one winding and the three phase output connected across all three windings. Some means is needed to get the rotor turning as with any single phase induction or synchronous motor.
The N&W electrics, the VGN Squareheads and the PRR Big Liz all used phase converters.
The term "rotary converter" traditionally referred to machines that combined a stationary field synchronous motor armature with a shunt wound DC generator. The armature windings would be connected to AC fed slip rings on one end and a DC fed commutator on the other end. Most of the power transfer between AC and Dc was through the windings as opposed to torque generated by the armature.
Rotary converters could also be used to convert DC to AC, with small units being used in the DC districts of major cities to provide AC power.
As I wrote before, the frequency changer set in Safe Harbor was/is a motor generator set. This is very different from the traditional meaning of "rotary converter".
- Erik
I find myself impatient for Rick Rowlands to finish up with his red Glyptal and get this running for at least one Youtube video, replete with zarks and other mad-scientist effects:
https://www.flickr.com/photos/33523379@N03/15178605648/in/album-72157647667854548
Quoting Erikem: "These were traditionally called phase converters, essentially being a free running three phase synchronous or induction motor with the single phase input connected across one winding and the three phase output connected across all three windings. Some means is needed to get the rotor turning as with any single phase induction or synchronous motor."
When I was working and issuing replacements to the line maintenance people, I was amazed that the techs could not look a the motor on a vacuum pump and tell if it were a single phase or three phase motors, for each of the single phase motors had one or more capacitors on it to give the motor a jump start. At firt, we kept all pumps of a certain size under one part number, but we made life easier on the techs by giving pumps with a single phase motor one p/n and pumps with a three phase motor a diffierent p/n.
Johnny
As an electrical engineer who was used to three phase power, I found this article of interest:
https://en.wikipedia.org/wiki/Amtrak%27s_25_Hz_traction_power_system
I had observed the transmission lines along the former PRR ROW and for some reason thought they were two phases of a three phase system and that the catanary made up the third phase. No. They are a single phase 69 kv to ground 138 kv phase to phase line and a second line on the other side of the ROW. I felt so dumb when I learned that I didn't know that. Utilities need balanced loads on their 3 phase lines and I should have known better.
As Johny Carsons sidekick used to say, "EVERY THING YOU NEED TO KNOW" is in the wikipedia article.
Back in the early years of electrification, when there were a few three phase electrifications (GN old Cascade tunnel, many lines in Italy), single phase electrifications were specifically called single phase.
While the ex-PRR 25Hz power tramission system is impressive, it is small potatoes compared to the 16 2/3Hz transmission system in Germany. The low frequency was originally used to allow for use of AC series (universal) motors.
Seveal other sites have had various criticisms of the cost over runs for the first phase of the constant tension CAT installation.
1. The replacement of present transmission poles due to their rusting out below grouns level. Using different methods to prolong poles.
2. Related to #1 is that poles are being placed closer than originals. Allows shorter spacing of cross poles that support CAT. That can be explained due to the problem of harmonic oscillations of the CAT under higher speed trains and also that NJT wants to run longer EMU trains with more PANs contacting which could cause possible oscillations.
Pictures of the work seem to show cross beams are being set at a much higher height. May be to allow Amtrak to raise CAT height above rail ? Possible plate "H" clearance ?
3. Extra heavy and extra tensioning of guy wires both parallel to tracks and cross wise. Trying to keep constant tension in spec ? Attach poles for weights will need extra guy wires.
Thoughts ?
I should note that although New Haven - Boston has been added to the NEC electrification, we have lost (1) Washington - Patomic Yard (including the Virginina Avenue freight rout, (2) Harrisburg - Enola Yard, (3) Newark - Waverly and Greenville, (4) Port Deposit - Harrisburg, and (4) Trenton Cutoff (does this track still exist?).
Part of the (3) still has electrification, 3rd-rail 600V DC for PATH and that part is owned by PATH now.
blue streak 1 Seveal other sites have had various criticisms of the cost over runs for the first phase of the constant tension CAT installation. 1. The replacement of present transmission poles due to their rusting out below grouns level. Using different methods to prolong poles. 2. Related to #1 is that poles are being placed closer than originals. Allows shorter spacing of cross poles that support CAT. That can be explained due to the problem of harmonic oscillations of the CAT under higher speed trains and also that NJT wants to run longer EMU trains with more PANs contacting which could cause possible oscillations. Pictures of the work seem to show cross beams are being set at a much higher height. May be to allow Amtrak to raise CAT height above rail ? Possible plate "H" clearance ? 3. Extra heavy and extra tensioning of guy wires both parallel to tracks and cross wise. Trying to keep constant tension in spec ? Attach poles for weights will need extra guy wires. Thoughts ?
Photos of standard PRR catenary set-up shows the catenary poles on a (cement?) foundation. Where did they rust out?
Are the cost over-runs because they did not anticipate replacing poles, or closer spaced poles?
MidlandMike Photos of standard PRR catenary set-up shows the catenary poles on a (cement?) foundation. Where did they rust out? Some other sites say that some of the poles actually go through the concrete caps and into the ground ? It will take some one near by to clarify ? Are the cost over-runs because they did not anticipate replacing poles, or closer spaced poles? Some one posted a OIG report about that but cannot find it ?
Some other sites say that some of the poles actually go through the concrete caps and into the ground ? It will take some one near by to clarify ?
Some one posted a OIG report about that but cannot find it ?
Switzerland also had 3-phase electrification through the Simplon Tunnel to Domodossola, Italy. This was extended west along the Rhone Valley to Sion during WW1 due to the extreme shortage of coal. Two of Switzerland's highest climbing rack railways still use 3-phase power. The Gornergratbahn which climbs from Zermatt to the summit of the Gornergrat at 10,135 ft. The second is the Jungfraubahn which climbs from Kleine Scheidegg through two mountains to the station at Jungfraujoch at 11,709 ft., the highest railway station in Europe.
Switzerland's B-L-S was electrified from the beginning at 15KV 16 2/3 hz single phase. The Burgdorf Thun Bahn (part of todays Regionalvehrkehr Mittelland (RM)) had an early (1899) three phase (Drehstrom) electrification (750 v 40 Hz) which connected with the BLS at Thun, converted to 50 Hz in 1920, converted 1932/1933 to single phase to deal with otherwise impossible crossings and joint track.
Thank you for the interesting discussion. I understand three-phase transmission, and motors. But how would you provide three-phase power to a locomotive? I see track, presumably at ground, and a single overhead catenary wire - two conductors. How can we get three-phase from that into the locomotive?
Three-phase electrifications generally had two trolley wires, or two catenaries, spaced about 0.8 meters, slightly under three feet, apart, with the track being the third conductor. Rode Tirano - Sondrio, Italy, on the Via Alpina Railway, Spring 1960, after riding Ratian Railways, Ratischa Bundesbahn, meter-gauge, San Moritz, Switzerland - Tirano. The car I was riding (rear) was switched to the rear of streamlined articulated 3000V DC unit in Sondrio for the trip to Milan. The 3-phase loco was a steeplecab with two full-diamond pantographs side-side on the cab roof.
A friendly Italian family insisted on my sharing their copious meal. Lot of bread, cheese, pasta, tomato sauce, eggplant, don't remember the meat and may have avoided it.
Regarding (as mentioned in Part II of the article) motor-generator sets to supply 25-cycle power to the Bethlehem Steel plant in Bethlehem PA, in 1954 I was inside that plant, as an employee of Pennsylania Power and Light Co. (PP&L), for testing of some equipment now unremembered. I found it intriguing to observe that, in the building I was working in, there was a 60-cycle AC generator that was running as a motor, shaft-coupled to a 25-cycle synchronous motor, this latter running as a generator to supply 25-cycle power. In use the combination would've possibly been started up from the 25-cycle side (if such bus voltage was available), via the motor's amortisseur winding, and then synchronized with the 60-cycle mains. It was a very interesting example of the reversibility property of synchronous AC machines.
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