Thursday, December 20, 2018

Pennsy Bridges at Conestoga River Mouth


Mike Froio shared
The mouth of the Conestoga River at Safe Harbor is crossed by two massive bridges of the former Pennsylvania Railroad. The higher span at left is the Atglen & Susquehanna Branch, part of the freight only Low Grade line between Enola and Morrisville completed in 1906. The lower span is the Columbia & Port Deposit Branch which makes the remote run down the Susquehanna, connecting with the PB&W in Perryville, Maryland. Safe Harbor is the location of a massive hydroelectric dam that still generates power for the electrified Northeast Corridor.
Mike Froio A historical piece I wrote on the spans back in 2013.
Douglas Allen Yes... The NEC's Catenary 25-Hz power is generated there. Amtrak has installed Static Invertors along the NEC, to also provide the needed 25-Hz power. (Commercial Electric Power is supplied at 60-Hz power).

From Wash DC to NYC, the Catenary is 25-Hz
, nominal 11kV, but usually measures closer to 13kV. 

Above NYC to NH, CN, the catenary is feed with 60-Hz @ 11kV (nominal), then from NH, CN. to Boston, the catenary is energized with 60-Hz @ 25kV.

Sensing equipment on modern electric locomotives monitor the supplied catenary voltage, and re-configure the main transformer for the High or Lower Voltage, and the semiconductor's firing pulses are controlled in-phase with the catenary's frequency.

PRR Electric Locomotives operated on the 25-Hz, 11-kV power.
Woody Massara As a matter of interest, the yard office and car inspectors shed at West Yard were powered by this 25hz. system. You could just discern the slight flicker to the lights.Douglas Allen Mike Salvatore,
The Catenary Voltage at the Wilm Shops Yard would measure at 13.5 kV most times, but was rated as 11-kV nominal. The transmission voltage is always boosted slightly to off-set voltage drop that occurs from distance from the source, and
the load that is being drawn from the catenary system during the time you read the voltage.

When working in the Equipment Engineering Dept @ the Wilm Shops, I worked with the Electrical Engineer from Ogontz Co, located in Philadelphia, who was developing the Traction Motor Load Meters installed to the AEM-7 Locomotives. This modification was added to the AEM-7s just after they were undergoing their first 4-Yr Overhaul Program.

In addition to the 4- LED Bar Graph meters, designed to indicate the load currents of each individual Traction Motor, a 5th Bar Graph Meter was installed to display the Catenary Voltage. 

This was done so the engineman could visual check to see that he had catenary voltage, in the event that the locomotive was not operating. 
Douglas Allen Woody Massara,
I worked as the Foreman in the Relay Room at the Wilmington Shops (Electric Shop) for some years. The Electricians that performed the periodic inspection on the Cab Signal Test Loops at the West Yard, and several other locations, fell u
nder my job. I would also accompany them to the West Yard to see the conditions of the wooden trunking installation for these Cab Signal Test Loops.

Locomotives dragging an air hose, etc... would catch on the test loops and damage them. At on point, in the 1970's, I determined it was time to perform a new installation of these test loops.

I had MOW Carpenters cut and fit new creosote soaked 2" x 4" lumber to the ties, within the gauge, and my electricians installed new copper wire in these frames. A 1" x 4" lumber cap would be installed after the new wire was installed.

The Yard was owned by Conrail at this time, as it was shortly after Amtrak took over the management of the Wilm Shops. I remember that SEPTA was operating the old MP-54MU Car, as well as the early Silverliner Cars, from Philly, to Wilm, DE... and would stop at the West Yard, before returning North, back to Philly. At the West Yard, a Mechanical & Electrical Inspection test would be performed, that included a Cab Signal Departure Test.

I hired on under the PC in 1970... and retired from the Wilm Shops, under Amtrak, in 2010.
Mike Salvatore you are talking to someone who was a lineman then a Power director for 40 yrs. I know a whole lot about the system then you think. as for the bar meters, the so called experts never took into account that the meter was measuring the voltage at point of usage. just as I proved to the expects at Sieman's the acs64s wree tripping breakers at various point due to the un-natural chopped wave form being slammed back into the system causing the relay protection to chatter and activate when in regeneritive mode.Douglas Allen Mike Salvatore,
I remember the growing pain with the sensitized AC power, generated by the new AC-Propulsion locomotives, to send power back to the Catenary wire during regenerative braking & maintaining their DC-link voltage. 

We had a problem with the AEM-7AC... they were literally "cooking" their roof-mounted resistors (ex-Dyn Brk Grids), when parked at Washington DC Station. I believe this was due to the same problem?

A Mike Froio Presentation Announcement
[It has a little higher resolution version of the photo.]
Another view of the bridges:
Jack Stoner posted
On a humid and steamy June day in 1986 Conrail train MTPI - Metutchen, NJ - Pittsburgh,PA crosses the iconic PRR Low Grade trestle, (local parlance) at Safe Harbor, PA. The actual Conrail nomenclature for this line was the Enola Branch. Taken out of service in favor of the Reading RR route to northern NJ and NY and Phila. this well engineered line was downgraded, then abandoned in 1989 and finally the last iron was removed in 1990 - 91.

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