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Friday, March 25, 2016

16-03-25 PHOTOS: PERRY

Perryville, MD is a fairly popular railfanning location on the east bank of the Susquehanna River. It is the northern terminus of MARC's Penn Line service which provides a platform that offers views of Amtrak trains crossing the Susquehanna River bridge. It is also the junction between the formerly electrified Port Road Branch that continues to provide freight access to the Southern NEC markets of Baltimore and Wilmington. Finally it is a key node on Amtrak's 25hz traction power distribution system where 4 138kv circuits from the Safe Harbor running on a private right of way tie into the lines serving the NEC.

Since I am often driving up and down the I-95 corridor I decided one afternoon in March to take a couple of hours and see what might show up. You can see the full set of photos here.

One never has to wait for PERRY tower to show up because it's always there. The brick structure was constructed as part of the PRR's wartime improvements along the NEC. A US&S all electric interlocking machine controlled the local plant while a CTC console controlled switches at GRACE and OAK interlockings on the far side of the river and QUARRY and MINICK interlockings on the Port Road Branch.

A northbound Acela Express trainset was first to arrive bracketed by power cars #2017 and #2036.

Due to the lighting I opted for video with some of the trains. Here a pair of Amtrak Regional trains hauled by ACS-86 locomotives #622 and #640 cross the Susquehanna River bridge. Speed across the bridge is 90mph.

Another northbound Regional with ACS-86 #645 passing PERRY tower.

Class leader ACS-86 #600 runs past with a southbound Regional train.

MARC Perryville station platform with the old PW&B station building.

Video of Northbound Amtrak Acela Express train crosses the Susquehanna River at Perryville with power cars #2029 and #2026.

Southbound AX with power cars #2021 and #2024.

The Perryville substation is one of the largest (by area) on the former PRR system and can switch current between 4 circuits 138kv west to Safe Harbor, 2 138kv circuits north to Philadelphia and 2 138kv circuits south to Washington. You can see a diagram from the old Philadelphia power dispatch office here with an explanation of the symbols here

Here you can see the 4 Safe Harbor circuits terminating on the upper beam while the lower beam serves the 12kv bus on the other side of the 1SL transformer. Amtrak replaced almost all of its legacy transformers in the 2005 time frame.

Two sets of extra switches allows for additional power routing options. Usually at least one switch will remain open to avoid tying every line to every other line. These switches are not circuit breakers and cannot be opened under load.

Some of the insulators are original to the 1930's, while a few have been replaced over the years with modern equivalents. The switchgear was remotely operated from the beginning and with some exceptions the local towers controlled the section breakers while the power dispatcher could manipulate the HT network.

To save on costs, the PRR only installed circuit breakers on the 12kv side of its power network. The three exceptions were at Thorndale, ZOO and here at Perryville where dead tank 138kv oil filled transformers allowed parts of the 138kv network to be isolated under load. Each of these parts were anchored by a major power supply point (Port Richmoond, Lamokin and Safe Harbor). Because the hydro turbines at Safe Harbor could become out of phase with the rest of the PJM grid, phase break signals were installed at Perryville and Thorndale and are still used on occasion.

While having only three sets of 138kv breakers did save on capitol costs, it did leave the HT network exposed to outages and is why wide scale power disruptions occur with some regularity on Amtrak. When one of the HT sections goes down, everything connected to it must be completely unloaded in order to then operate the switches and isolate the fault. 

Amtrak substations also supply 6.6kv, 100hz signal power.  This hat rack was located outside the fence line, distributing signal power circuits to the catenary poles.

Power is delivered from Safe Harbor via commercial style pylons. One can identify the Amtrak 25hz power lines because each single split-phase circuit consists of two wires as opposed to 3 in commercial 3-phase transmission grids. Split phase means that each wire carries only 69kv with respect to ground, but double that with respect to each other. This allows for the size of the insulators to be reduced. 

A public dock on the north side of the Susquehanna River bridge allows for additional photo angles. Here Amtrak Train 92 heads north behind ACS-86 #639.

Because of Amtrak's scheduling meets are not uncommon at Perryville. I was getting in my car when I was caught out of position for a Regional meet involving ACS-86 #617 and another I couldn't identify.

Well that's it for today! Next week we'll see what's new at Brunswick.

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