henry6 A term misinterpreted here has been "phase gap". It it the neutral or dead gap between two similarly powered sections of cat and not the glide space between the two different power voltage systems.
A term misinterpreted here has been "phase gap". It it the neutral or dead gap between two similarly powered sections of cat and not the glide space between the two different power voltage systems.
Yes, henry6 is correct. I don't know if anyone else has been following a thread on another forum, but I've learned a lot about it.
At a PHASE GAP, (section of unpowered/isolated catenary between two sections of the same catenary [like at Red Bank, for example]), a train must a) lower pans completely if it is traveling at 25mph or less, or b) not draw power, but may keep pans raised, if it is traveling more than 25mph. I'm not sure exactly why PGs exist, but my guess is that they divide the catenary because different parts are powered by separate substations.
At a Voltage Change, such as at Kearny (SWIFT or the Waterfront Connection) or Matawan, Arrows can not travel through. As I mentioned before, the switch on the Arrow IIIs for the different voltages, is located under the carbody. The train must come to a complete stop, before the crew can go down there and flip the switch.
Also, there are no phase gaps on the NEC that I am aware of.
Hope this helps.
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Just to throw something dirty into the wash: a one time electical engineer for the PRR, then Conrail, once proudly told me that on the old PRR when a power station went down in NJ they could throw power across the whole system from a station, I believe, in Wilmington, DE and still have full power at Sunnyside Yard! As noted there were no phase gaps on the former PRR. Nor the NH. Nor the DL&W. Nor the LIRR. Nor the NYC. Only on NJT! (Oh, yeah, the New York subway has them at switches, though.)
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Makes me sad that Conrail felt the need to pull down the catenary on 'their' parts of the NEC. There is so much electrical capacity on the NEC it's unbelievable to me.
As for what a Phase Gap is, the power is generated by several sources as you know. These sources have to be synchronized with each other at the same time instantaneously when they come online. This is really hard and expensive to coordinate. It's just easier to separate the sections where practical. Case in point, a motor-generator converting a 60 Hz source to 25 Hz in New Jersey must be timed so it become "in-phase" with the hydroelectric 25 Hz turbines (at several dams) that power the other parts of the system, and they all have to alternate at exactly the same time. Instead, just separate them so they don't have to synchronize.
It's a little more complicated but that's the basic concept.
Somewhere else in this forum there was mention of a phase gap in Delaware.
aegrotatio Makes me sad that Conrail felt the need to pull down the catenary on 'their' parts of the NEC. There is so much electrical capacity on the NEC it's unbelievable to me. As for what a Phase Gap is, the power is generated by several sources as you know. These sources have to be synchronized with each other at the same time instantaneously when they come online. This is really hard and expensive to coordinate. It's just easier to separate the sections where practical. Case in point, a motor-generator converting a 60 Hz source to 25 Hz in New Jersey must be timed so it become "in-phase" with the hydroelectric 25 Hz turbines (at several dams) that power the other parts of the system, and they all have to alternate at exactly the same time. Instead, just separate them so they don't have to synchronize. It's a little more complicated but that's the basic concept. Somewhere else in this forum there was mention of a phase gap in Delaware. First, as explained elsewhere above, a phase gap is a dead zone between two zones of the same power and not between two different power sources as you have described. Second, CR did not pull down wire on the NEC but rather on branch lines along the Susquehanna south of Harrisburg and from Harrisburg east to Paoli and on freight routes circumventing Philadelphia. The Corridor itself from New Haven to Washington, DC, remains intact (sort of...it keeps falling down in many places because it is so old and has to be replaced!).
First, as explained elsewhere above, a phase gap is a dead zone between two zones of the same power and not between two different power sources as you have described.
Second, CR did not pull down wire on the NEC but rather on branch lines along the Susquehanna south of Harrisburg and from Harrisburg east to Paoli and on freight routes circumventing Philadelphia. The Corridor itself from New Haven to Washington, DC, remains intact (sort of...it keeps falling down in many places because it is so old and has to be replaced!).
Conrail did pull down the catenary on the freight "High Line" bypass around 30th Street Station, and believe me, Amtrak certainly wishes they had not done so! Now, I am not even sure the track is still in place!
CSX uses the high line frequenly. My understanding is that AMTRAK has wanted to reinstall the CAT and get trackage rights in case of difficulties at 30th street station but CSX has said no so far.
henry6there were no phase gaps on the former PRR. Nor the NH. Nor the DL&W. Nor the LIRR. Nor the NYC.
NH only had one power plant, didn't they? So no need for gaps? And no need for gaps on DC electrifications like DL&W-LIRR-NYC?
SEPTA Silverliner Vs are speced to pass through phase breaks with power on. Must be other breaks on the NEC and old RDG CAT.
After reserch the latest EMUs should have no phase break, voltage, or frequency problems. Example: SEPTA will have AC propulsion on their Silverliner Vs. The transformer on the car provides either 25Hz 11Kv(nominal) or 60Hz 12.5 Kv (doesn't matter which and no switching required) with transformer output going directly to 4 wave rectifiers that supply various inverters (traction, passenger convience, emergency, battery charger, signals, communications, etc. The AC traction motors can supply regenerative braking first to all the above car electrical and then to the CAT (if it can take the power) or to dynamic brakes + the cars are also going to have blended braking much as AMTRAK. The specs require a MTBF(mean time between failure rate) of 50,000hr service for the traction motors.
A provision for the transformers is that they are all wired for a 25Kv transformer tap and for SEPTA to be able to install automatic switching on each car individually as a car passes into a different voltage (ie 11Kv/12,5Kv - to 25Kv). So the Silverliner Vs will be able to go from WASH to Sunnyside now and with the tap switching installed will be able to go WASH - BOS with no change of any power sources on the present NEC..I suspect that MN/CONNDOT's new EMUs will do the same with the additional priviso of third rail imput to their inverters.
That is what I have been told about the Metro-North ConnDot NH Line mu's on order. Because ConDot does want Penn Sta. Access (West Side Access), and also wants to be able to operate the cars in Shore Line East service.
It is hard to tell whether there is any equivalent third rail dc phase break. At every switch there is always a gap in the third rail and the reason is obvious, and this is true no matter which side of the track has the third rail. It is up to the power engineering people to determine whether all dc output substation should be tied together on a common hot bus all the time or whether sectionalization is important. Both methods have advantages. A common hot bus does not mean a poor performing substation cannot be taken off line, since all that is necessary is to open the output feeder circuit breakers for that station.
So wouldn't it be cheaper and easier for all overhead wire from Boston to the south and west be of the same standard instead of gaps, changeovers, different equipment. Railroads succeeded when 4ft 8 1/2 inches was adopted, knuckle couplers and Westinghouse's air brake system was adapted, and other standards were set. Why shouldn't they (not couldn't, shouldn't) they do that with continguous electric power for Amtrak, ConDOT, NJT, SEPTA, and MARC?
Phase Breaks: What are they? Since AC power is three phase with each phase 120 degrees different than the other two each on its own sine wave. Imagine three overlaping sine waves.That is why if you are in an urburn or only semi rural area there are three primary power lines to your transformers. In some areas the transformer is connected to two phases and other locations (esp the south the transformer is connected primary to ground). The winding ratio gives 120/240 V to your house. In most areas the primary to ground voltage is 7200V and Phase to Phase is not 14000V but about 12,800V.
The power generators (commercial and RR) strive to balance the load on all three phases. New high voltage power transformers are wound to mitigate some unbalance (don't remember how much) but the old PRR, RDG, & NH systems probably could not. All overhead AC CAT is now single phase (I recall that GN had a two wire 2 phase system). RRs and light rail are an unique problem because the loads are naturally unbalanced. Now if the RR source in one section is Phase A and the next section Phase B then a phase break is necessary. Breaks are only about 1 ft so even powering through a phase break for modern electrical equipment will never be felt because the power goes immediately to a rectifier. Older equipment such as a GG1 and MP54 had motor generators and the sudden 120 degree phase shift was not good for the motor so coasting thorough a phase break was called for. Remember also that modern CAT usually have a lot of isolation points that are on the same phase and you never notice them and i've not noticed anything through a phase break even when in an older car. 1ft at 60MPH = 1/88 of a second (60MPH = 88ft/sec).
Actually there is an effort to become standard but its going to cost a lot of money and time (probably 20 yrs). Upgrading CAT to 25Kv is the first item then all the electrical equipment both rolling stock and trackside equipment. electrical lot. There are no phase breaks on AC to third rail because the source to inverters is switched from the rectifiers to the third rail shoe. Don't know the relay speed.
There is usually a break between different DC power stations and also isolation points. You can especially notice them on the NYC transit subway cars as they go black for a very short time on the older cars. Not so noticeable on MN
On NJT phase gaps are between two same power sources. At Baker (wes of Morristown Sta.) for instance, west of the gap is fed from Denville Sub while east of the gap is from New Providence (P&D Juct.) sub. Jumping between sub stations would cause great problems with train and substations, thus the gap. The gap at the junctions of the M&E and Corridor (and west of Matawan on the NJCL, nee NY&LB) is between two dissimilar power sources and thus the need for changeovers inside the train.
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