Skip to comments.Explosion on Bridge Caused by 'Thermic Event:' Police
Posted on 02/01/2013 7:21:28 PM PST by fatima
Four people were hospitalized with minor injuries Friday night after an explosion on a bridge over the train tracks at 30th and Cecil B. Moore in Brewerytown.
The explosion was originally thought to have been an explosive device, but after an extensive investigation, police are calling it a "thermic event."
(Excerpt) Read more at nbcphiladelphia.com ...
17,000 volts AC at 16 hertz can cause a lot of damage if bridged by frozen water. I wouldn’t want to be nearby.
What’s a “thermic event,” an explosion set off by Muslims?
No, it was set off by Therms. Gee, try to keep up.
Off with there heads!Thermahu akbar!
Depending on where you are, the frequency on the Northeast Corridor can run from 16 to 60 hertz. It has to do with who electrified that stretch of track originally. Thanks to the modern art of thyristors, today’s electric locomotives can change on the fly.
Yeah, it Hz a lot!
Crazy stuff,my daughter takes this train everyday.
“Chief Sullivan says icicles formed as a result of the recent moisture and these icicles came in contact with high power lines from AMTRAk that run underneath the bridge.”
What a idiot I is. Their heads not there heads.
Global Warming: It makes bridges explode.
Was Al Gore seen lurking in the neighborhood?
Back in the Sixties, I commuted on these lines when I was in college.
He’s too big to lurk.
Now we know what happens when his chakra is released....
We got it anyway.
Why can’t they simply call it a short circuit caused by icicles touching the third rail?
“Thermic Event”, huh?
Not third rail. Overhead caternary.
Good thing this never happened back before glogal warming.
16 , 17 Hz. Whatever it takes.
16, 17 Hz. What Difference Does It Make????
A “thermic event”
Must have been written by the same government weenie who brought us:
“overseas contingency operations”
“affordable health care”
DC I understand. 50/60 Hz I understand. 400 Hz I understand.
I don’t “get” 16 Hz. I even think the 25 Hz used in some parts of the world is too low. Visual flicker on the lights, unnecessarily large transformers, etc.
16 Hz? Why would they do that???
You would need to talk to the guys who electrified that stretch of the Pennsylvania Railroad’s Northeast Corridor in 1933. It made sense to the electrical engineers of the time. It probably doesn’t now.
Disco all the time.
Sounds like some old motor generator set that’s older than dirt, and maybe older trains needed (need?) the low frequency to run special slow synchronous motors. Just a guess... today, if trains can deal with multiple frequencies, it would of course make sense to tie it directly into the utility with transformers and have it be 60 Hz.
They probably wiring in heaven now... I would guess it was a need of synchronous motors on the trains of the time. The capability of rectifying the currents required to move a train had to wait for the era of silicon semiconductors.
Heck of a thing for epileptics
Correct, I’m sure. In the old days, there was a locomotive change at the Pennsylvania Station in New York, and not just because the New Haven took over from the Pennsy. The New Haven’s 1906 electrification was set to a different frequency.
Sorry, my misinterpretation of the story. I figured that below the roadway meant 3rd rail.
I was thinking of the old DC trolleys when I was a kid. Underground 3rd rail in town, but they did go to overhead catenary once out of the built up areas, like the run to Glen Echo.
When the DC system was built in the late 19th Century, Congress mandated that the trol;eys use third rail within an underground conduit within the District. They went to caternary wire outside the District.
The former Pennsylvania Railroad section of the Northeast Corridor is electrified with 11,000 volt 25 Hz, as are the former Reading commuter lines. I need to check the historical basis for the lower frequency. Apparently it was a combination of transmission losses, and being able to operate “universl motors” that could operate on DC.
The 17 Hz is actually 16 2/3 Hz of the Deutsche Bahn (1/3 of 50 Hz).
Those are old legacy systems
In 1997, I read Michael Bezilla's The Electrification of the Pennsylvania Railroad, and now it's out of print. I was going from a failing memory.
The old New Haven was also at 25 Hz. There used to be a locomotive change at Manhattan Transfer (not far from the current PATH Harrison station), however, the original Pennsy New York electrification was third rail (600 vdc) from Sunnyside Yard to Manhattan Transfer in order to enable tunnel operation under the Hudson and East Rivers. When the PRR extended the 11kV catenary from Trenton to New York, Manhattan Transfer was eventually done away with.
Now the former New Haven line is 12.5kV 60 Hz to New Haven (formerly 11kV 25 Hz, the old NH power system was badly worn), with the new Amtrak electrification from New Haven to Boston at 25kV 60Hz.
Thanks for bringing me up to speed. I was drawing a blank on the 1999 Amtrak electrification to Boston.
Anyway, the history I learned was that a most trains had standardized on large DC commutator motors, which could also be used in AC. Problem was, the higher the frequency, the more internal inductance problems you had. 25 Hz was a good compromise between internal inductive loss and transmission loss on the line.
They are a radical group called ‘Hz-bull-duh ‘!
A radical group of electrons , inconvienced , and doing self-immolation.
Thermahu Akbar !
Yeah that’s mostly my understanding (see previous post.) With AC you could mitigate the huge transmission loss you get with direct current, but as you increased the frequency you start to have higher and higher inductance losses in the windings of a DC motor. 60 Hz was too high for those motors. 25 Hz was a trade-off point between internal losses and line losses.
Thank you gentlemen.
I assumed that there would be a FReeper who actually knew the answer.
Two is an unexpected bonus.
Oh Dear ! All this thermic stuff beats the Hertz out of me.
“17,000 volts AC at 16 hertz can cause a lot of damage if bridged by frozen water. I wouldnt want to be nearby.”
Amtrak catenary on the New York to Washington segment is energized at 11,000 volts 25hz.
Going under an overhead bridge, there’s not a great distance between the bridge structure and the wire itself — the insulators are often short there to maximize clearances between the wire and the rails. What happens is that water which under warmer conditions might drip bridge-to-wire freezes and then extends downward until it may touch the wires, then — zap!
You gave me a good laugh with that one.
25Hz power came from the design RPM of the Westinghouse Niagra Falls turbines, which were designed before alternating current became the standard. They could not change the hydraulics, so they had to chose between 16-2/3, 25, and 50Hz. 16-2/3 caused flicker, and 50 didn’t work for the motors of the day, so they settled on 25.
To #19. Overhead caternary?
Well, put up chicken wire to keep them darn cats and canaries off the electrical wires.
By the way, he you entered that word in the New Dictionary of corrupted American words?
Ugh, make that icky therms!
Thermic Event = Massive Tig welder.
Probably not. There was no report of a seismic event at the same time.