Amtrak wayside signs

On the Amtrak Catenary poles near MP 199.34, there is a sign on the pole with white letters, DS, on a yellow background. This sign is located about 1.5 miles from a crossover from Track 1 to Track 2. what do those letters stand for?

Hey F40, I believe you asked this before and I replied on the old RR.net. Perhaps it was not you that posted it, but here you go..........

The letters "DS" stand for "DEAD SECTION". which is just that, a dead section of catenary. There are a few dead sections on the NEC because Amtrak has more than one supplier of electricty, and each supllier's portion of the line is seperated with a "Dead Section" so that they can account for the amount of energy provided to Amtrak along the specified portion of track.

As far as these signs. The "DS" sign with a yellow background is an "Approach Dead Section" sign, which reminds the engineer of an electric train that he is approaching a "Dead Section". The "DS" sign with black and white background designates the beginning of the "Dead Section".

Hope this helps.

Another term i herd was phase or phrase break. to add to what csx conductor said the engineer must lower the throttle and there is a switch in the cab that you set to approach the change over then when your at power again you move the switch back again and you have power again :D You must wait 20 or so seconds before kicking the throttle up again.

Is this why you frequently (especially north of NY) have the power go out when riding Amtrak on the NEC?

I'm guessing yes. I use to think the HEP cables were getting loose.

>>>The letters "DS" stand for "DEAD SECTION". which is just that, a dead section of catenary. There are a few dead sections on the NEC because Amtrak has more than one supplier of electricty, and each supllier's portion of the line is seperated with a "Dead Section" so that they can account for the amount of energy provided to Amtrak along the specified portion of track. <<<

The breaks in the catenary are not directly related to different electric suppliers. They are primarily there so catenary sections can be isolated for maintenance. Amtrak takes power off the grid at its substations at high voltage where it is metered. Subject to transmission capability and reliabilty as well as power purchase contracts, Amtrak will take the cheapest electric it can get and wheel it anywhere on its system. At Amtrak's substations the transmission level voltage is (in the 60Hz section, NY to Boston) directly stepped down to the catenary voltage. Between NY and Washington/Harrisburg there is an intermediate step where the frequency is changed to 25Hz. Most of that is done by new solid state converters, but interestingly, an original 25-megawatt rotary converter installed as part of the orginial PRR project in the early 1930's is still in daily use.

Very interesting. I'm guess the "CUT OUT" signs on the MBTA green line catenary fulfill the same function.

thanks everyone :D

The Phaze Breaks marked with DS boards are not for catenary isolation. The phaze sections run something like 25-50 miles which would be far too much for maintainence needs. The overhead can be isolated down to much smaller sections, usually between interlockings. The Phaze Breaks are to isolate the sections that are on different power feeds from the grid. Power companies also don't like someone sucking up just one of their three phazes so this lets Amtrak draw a fairly even amount of each phaze from the grid.

On the PRR and MNRR segment of the line they have true Phaze Breaks where the break may or may not be active. They are protected by a Phaze Break signal.

Also, much of the Harrisburg power division is served by a dedicated 25Hz turbine at the Safe Harbour dam.

But wouldn't the PRR section not need phase breaks since the 25 Hz is independent of the grid? The balancing of power is done at the converter stations and no phase breaks would be required for that purpose. Just to be able to isolate sections or for power control from the RR substations.

And, contrary to popular belief, phase breaks are NOT needed because every power supplier is 'out of phase' with every other one - all power suppliers east of the Rockies, and outside of Texas, are in phase (to allow sharing power). West of the Rockies everyone's in phase with each other, and Texas is like that too. The electric grid wouldn't work, otherwise.

The PRR section has phase breaks, which I always found odd because everyone says the whole thing's single phase, but that doesn't make sense either. Could be 2 phase (4 wire - weird stuff) - there's a LOT of that out in the Philly area.

The one thing I never understood was Amtrak's big hangup with passengers having to go down to the trackbed and back up to and adjacent train, when evacuating a dead one on the NEC. The supposed reason is that you'd get electrocuted if you touched two trains at the same time (i.e., there's a voltage difference between the two car bodies that's quite significant), but this makes NO electrical sense whatsoever, as it'd mean that interlockings and such would be electrically impossible, period. And in any case, could be elimanated by simply lowering the pantographs...

The Amtrak procedure does make sense since unless the adjacent tracks were electrically bonded at fairly close intervals there could be a significant electrical potential between the two since the impedance of the two tracks is likely not identical. The heavy current flows from train operations would create a significant differential. As to interlockings, perhaps they are insulated for signal or other purposes? In any event, even if the tracks are bonded at the interlocking, several miles away would more likely be at different potentials. Even a one percent difference would be a 120 volts.

---Ken