Acela Speeds

One final bit before i move on to another topic...

The arcing in that shot has no pattern. In numerous places on countless occasions i have witnessed first hand long strings of arcing. The usual culprit if not ice is a fresh carbon strip on the pantograph shoe. If one puts 2 and 2 together, a test train, must have fresh carbon strips, and fresh carbon strips prone to arcing = woah i guess it was the fresh carbon strip causing the arcing!

Now. I hugely respect anyone on here who is a conductor or engineer etc, their knowledge and experience, but i will not be bullied and defamed on an online public forum. I don't know everything about railroading, but the things i do know are a combination of countless observations and being informed by the professionals who's job it is to know. If you have something to say, PM me, leave it off of the threads. If i'm wrong i'll be the first one to be happy to be corrected!

25Hz wrote:The sparks happen for a lot of reasons, and the pantos have springs in them that push up against the contact wire pretty firmly.

I have often witnessed similar arc spots along very busy stretches no matter what train it is passing under.

http://www.youtube.com/watch?v=tYP-asIM ... ature=plcp

If you see the related video pulling into EWR, you'll see same time pattern. I am thinking this has to do with the transformer and power electronics.

@Tadman: The curves through bucks county mean the train has to slow and then speed up, so you often see a lot of arcing, especially as they exit the curve!

Since this is a single phase system an arc occurs only when there is a path from the catenary wire to ground and the contact surface on the pantograph is not in contact with the wire, I.e., there is an air gap small enough to allow the arc to occur. Transformers and controls would have nothing to do with an arc. Movement of the wire results in the air gaps. The wire moves due to the varying pressure of the pantograph as both laterally and horizontally as the train moves vertically and horizontally on its suspension. This is compounded by the variation laterally and vertically of the catenary versus the rails and the differing tension at any given point.

25Hz wrote: Lets also not forget that those arcs were also right next to the "nassau" substation, and there were not other trains running, so all the power was going into that one pantograph without the system balancing another train. I'm pretty sure they planned it that way, not just because at night has less traffic, but less trains = stable voltage & amps.

That location relative to substation has nothing to do with the sparking, nor does any interaction with transformer and electronics. The sparking thing is a purely mechanical thing due to relative motion of the contact wire and the panto. But of course I am not going to argue about it either. Just sayin'

Jishnu wrote:

25Hz wrote: Lets also not forget that those arcs were also right next to the "nassau" substation.

That location relative to substation has nothing to do with the sparking. The sparking thing is a purely mechanical thing due to relative motion of the contact wire and the panto.

I think he's suggesting that higher voltage allows an arc to cross a bigger air gap.
However, I suspect that the gap produced above the Acela in the cited movies is probably less than the gap an arc can leap at lower rush hour voltages. Watch the arc produced when a pantograph is intentionally lowered.

JimBoylan wrote:

Jishnu wrote:

25Hz wrote: Lets also not forget that those arcs were also right next to the "nassau" substation.

That location relative to substation has nothing to do with the sparking. The sparking thing is a purely mechanical thing due to relative motion of the contact wire and the panto.

I think he's suggesting that higher voltage allows an arc to cross a bigger air gap.
However, I suspect that the gap produced above the Acela in the cited movies is probably less than the gap an arc can leap at lower rush hour voltages. Watch the arc produced when a pantograph is intentionally lowered.

I'm not necessarily going to take a side in this argument, however I will say that there's a difference between a bouncing pantograph and a lowering pantograph. There's a light switch in my house that if I hold the switch at just the right place after it's been on, I can hold an arc, but I don't hear or see an arc when I just shut it off. I'd imagine the same kind of thing is applicable here.

I'm not taking sides either, but there definitely is truth to the fact that when there are two pantographs there is more arcing. Have you ever seen the arcing from the second AEM-7 on a double header? It's much more compared to a train with a single loco. It would make sense if this is caused by the first pantograph making catenary movements that interfere with the perfect electrical connection and cause arcing from the second pan.

MattW wrote:

JimBoylan wrote:

Jishnu wrote:

25Hz wrote: Lets also not forget that those arcs were also right next to the "nassau" substation.

That location relative to substation has nothing to do with the sparking. The sparking thing is a purely mechanical thing due to relative motion of the contact wire and the panto.

I think he's suggesting that higher voltage allows an arc to cross a bigger air gap.
However, I suspect that the gap produced above the Acela in the cited movies is probably less than the gap an arc can leap at lower rush hour voltages. Watch the arc produced when a pantograph is intentionally lowered.

I'm not necessarily going to take a side in this argument, however I will say that there's a difference between a bouncing pantograph and a lowering pantograph. There's a light switch in my house that if I hold the switch at just the right place after it's been on, I can hold an arc, but I don't hear or see an arc when I just shut it off. I'd imagine the same kind of thing is applicable here.

Exactly.

And yes, the rear unit will always have more arc because of the movement from the wire from the loco ahead of it. I have been inside a locomotive watching the reflection of its pantograph movement thru the windshield of the trailing unit. Something you cant see trackside is the amount of times that pan moves up and moves down again because the catenary is not smooth and flat. Almost every time you reach a steady span it raises up and then will go back down again. Its not a huge distance it moves but it does move.

So, it's october, did they ever get to 165, and if so, video of such?

25Hz wrote:So, it's october, did they ever get to 165, and if so, video of such?

Huh? There are videos of them doing 170 mph linked in this thread.

25Hz wrote:So, it's october, did they ever get to 165, and if so, video of such?

http://www.youtube.com/watch?v=FWf-ipNl5fQ

25Hz wrote:So, it's october, did they ever get to 165, and if so, video of such?

25hz: Allow me to clarify for you. All of the buffs that are touting the 165-170 tests and using rumor, hearsay and math to calculate speeds on the 24th are talking out of their rear ends. The train never made it past 162.3 during the testing on the 24th. On the 25th, 165 testing occurred the PW Line. When that was completed, the 160 test was repeated on the NYP Line heading east, the 165 test west and was attempted east. The same thing that preempted the 165 test on the 24th, stopped the 165 tests on the 25th. They were supposed to repeat the 160 and 165 tests last Monday, but since I was on vacation, I don't know if they actually took place.

Pay no attention to the wild, exaggerated claims by the people standing by the ROW. The train did not go by PJC at 170mph.

ThirdRail7 wrote:

25Hz wrote:So, it's october, did they ever get to 165, and if so, video of such?

25hz: Allow me to clarify for you. All of the buffs that are touting the 165-170 tests and using rumor, hearsay and math to calculate speeds on the 24th are talking out of their rear ends. The train never made it past 162.3 during the testing on the 24th. On the 25th, 165 testing occurred the PW Line. When that was completed, the 160 test was repeated on the NYP Line heading east, the 165 test west and was attempted east. The same thing that preempted the 165 test on the 24th, stopped the 165 tests on the 25th. They were supposed to repeat the 160 and 165 tests last Monday, but since I was on vacation, I don't know if they actually took place.

Pay no attention to the wild, exaggerated claims by the people standing by the ROW. The train did not go by PJC at 170mph.

So nobody used any other kind of technology to make the 170-mph claim? No GPS or radar guns or suchlike?

And how again is the FRA Tier II crashworthiness stipulation of "up to 150 mph" to be overcome?

amtrakowitz wrote:

ThirdRail7 wrote:

25Hz wrote:So, it's october, did they ever get to 165, and if so, video of such?

25hz: Allow me to clarify for you. All of the buffs that are touting the 165-170 tests and using rumor, hearsay and math to calculate speeds on the 24th are talking out of their rear ends. The train never made it past 162.3 during the testing on the 24th. On the 25th, 165 testing occurred the PW Line. When that was completed, the 160 test was repeated on the NYP Line heading east, the 165 test west and was attempted east. The same thing that preempted the 165 test on the 24th, stopped the 165 tests on the 25th. They were supposed to repeat the 160 and 165 tests last Monday, but since I was on vacation, I don't know if they actually took place.

Pay no attention to the wild, exaggerated claims by the people standing by the ROW. The train did not go by PJC at 170mph.

So nobody used any other kind of technology to make the 170-mph claim? No GPS or radar guns or suchlike?

And how again is the FRA Tier II crashworthiness stipulation of "up to 150 mph" to be overcome?

"up to 150 mph" - couple of options, informal call to FRA from White House to FRA, similar call from leaders of both legislative houses. Happens a lot inside the beltway.

I suspect that after the Florida high speed rail project was killed and a good portion of those funds redirected toward the NEC, someone said, "How can we get the most bang for the buck out of the Acela?" The tracks where Acela runs above 125 mph are already FRA Class 8 (160 mph), and the Acela's capable of 160, so a slight revision of the FRA tier II regs doesn't seem unreasonable.

The difference between "reasonable" and "likely" varies quite a bit in DC. As the old saying goes, seeing is believing. And as for 160 mph "bang for the buck", again I will say that it is forty years late.