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Thread: PRR Style Catenary Supports

  1. #11
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    In case anyone cares, those are called "bell" insulators (for obvious reasons).

    There are also several different sizes of them, depending on voltage and weight capacity. I possess some pretty hefty high-tension bell insulators.

  2. #12
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    Steve, those look really good! I like what I see.

  3. #13
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    Just for my own edification (and now yours, dear reader), I found the drawings of the insulators that I have. I've heard them referred to as "bell" insulators as well, and there are indeed, many other types, particularly if you take into account newer catenary installations post PRR, transmission lines, signal lines, etc. I'm aware that the Reading standards generally followed similar practice as the PRR (there was always the idea that the systems would be connected someday, and eventually they were), but I'd expect that NH, DL&W (with a DC installation) and other roads would've had their own standards for such things (although I'm aware the PRR drew on NH experience).

    The PRR had standards for insulators, not surprisingly, and the most common types used in catenary construction were the A-2, which was 12" in diameter and 7" in height, and the B-1 which was 10" in diameter and 5 3/4" in height. Those were typically stacked in a group of three, with different connections and clips applied depending on the application, such as for hangers, cross catenary, or steady spans. Certainly there were other types used in catenary construction, but these were the common ones, used for construction across the system. I think a notable exceptions would be insulators used in sectionalizing gaps and in areas of complex or "specialty" catenary (such as low overhead clearance), but these would have been exceptions, not the rule.

    Just add catenary to Silverliners, Ore Gondolas, oddball and Side rod electrics as another wacky railroad thing that Steve is interested in.

    Anyhow, I'm catenaried out for the time being, and am moving on to other projects.

    Steve

  4. #14
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    My latest models of PRR gantries, not available in PRR East, the correct configuration of insulators are shown. Stacked by three on the Catenary wiring. A correct insulator layout plays a virtual role in determining how realistic the gantry appears. I've also noticing that spacing gantries at prototype of 270' to 300' plays a virtual role as well. The most virtual role is making up that both the catenary leads and the high transmission wiring are matching sets!

    I do have a question though, on the high transmission supports, how many insulators are stacked on there? I've counted 10 of them!

  5. #15
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    Yes Kyle, it does look like 10 or 12.. but too tiny for me to count bit it looks like 10.

    Good to hear from you!

    Dave




    Quote Originally Posted by van2001ko View Post
    My latest models of PRR gantries, not available in PRR East, the correct configuration of insulators are shown. Stacked by three on the Catenary wiring. A correct insulator layout plays a virtual role in determining how realistic the gantry appears. I've also noticing that spacing gantries at prototype of 270' to 300' plays a virtual role as well. The most virtual role is making up that both the catenary leads and the high transmission wiring are matching sets!

    I do have a question though, on the high transmission supports, how many insulators are stacked on there? I've counted 10 of them!

  6. #16
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    On the issue of transmission insulators, I have less certain background information, mostly just observations. Going through my collection of catenary support structures (as Kyle and Dave both know, I actually photograph such things ), I'm seeing that a LOT of the high-voltage transmission lines (the upper ones seen on PRR catenary supports typical of the 1930's electrification) that 11 seems to be the most common number of ceramics.

    However, I wouldn't say the 11 number is universal. I have a great photo of one of he supports on the 5-track Schuylkill River bridge to the east of "Zoo" that shows four upper and 6 lower transmission lines. The ones attached to the northern support (2 upper, 3 lower) all have 12 ceramic insulators. The ones attached to the southern support (2 upper, 3 lower) have 11 ceramics for the upper 2 and 14 ceramics for the lower 3. Given how many transmission lines, and that the southern/lower ones have a different support crossarm, I think some of these are power company transmission lines (PECO? - not railroad) and so perhaps the voltage and insulation requirements are different. Remember that not all the wires up on those supports may belong to the railroad, they sold right of way to power companies to co-locate transmission lines on the catenary support structures. There are locations (the electrified portion of the ex-PRR Schuylkill Valley branch is a notable one) where the catenary has been removed (and in this case the tracks too) but the supports remain, carrying transmission lines, probably those of utilities. I don't have a great photo of those, but every time I drive up the Blue Route (476) toward the Turnpike, I see them, and I've seen the same at other locations (some of the low-grade freight lines).

    Wilmington, DE, is another place where utility transmission lines are carried on the catenary supports. The utility transmission lines are supported by structures grafted onto the top of the supports. Counting the insulators on those lines, I come up with 17, and at most locations I photographed, a line was supported by 2 of those 17 ceramic insulators. I recall Marcus Hook being another area with similar arrangement (but more lines).

    Another variant was the "halo" style (my term not the railroad's) which has insulators with a metal-appearing ring (like a halo) around the top and bottom. I have photos of these with 11 ceramic insulators, but I've seen them with fewer (a photo in the PRRT&HS "Keystone" shows one with a 7 ceramic insulator). I don't necessarily understand the purpose of these types of insulators, but I have noted that they seem to show up near substations, and other points where there are line connections (perhaps they serve a sectionalizing function, I don't know).

    On my model, I just observed, for some reason I'm using 12 ceramic insulators. I don't know why I settled on that (probably 3 or 4 years ago) but that's what they are. Honestly, this is one place where I believe the looser concept of "Many" probably suffices for the actual number. I read about a study in Scientific Amerian that mentioned that humans seem to have the ability to recognize the number of objects immediately up to about 6 or 7 and beyond that the brain recognizes "Many" - you have to count them as opposed to just seeing and knowing the exact count (the reason why guessing the number of jelly beans in a jar makes a good contest, whereas putting 5 out on a table won't even stump a 4 year old). I think that concept applies to these insulators.

    Steve
    Last edited by mestevet; 02-27-2010 at 09:45 AM.

  7. #17
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    Steve,

    Thank you for all of your valuable information! I appreciate your reports.. That certainly helped me a lot on studying PRR gantries. It also helped me to continue with studying around a lot more and taking some photos. (yes I gotta be careful, as people think Im a terrorist when it comes to power lines...lol) I also have been studying PRR style power substations where electrification breaks and splits and such. so the next trip I head back up the Northeast, I will be trying ti take some PRR style gantry photos along the way from DC to NYC. Then also, try to take some New Haven RR era gantries between New Rochelle towards to New Haven, then studying them a bit more in detail. I will also share you some of my NH gantry shots when I get back home. (mid to late May)

    Again, thanks for your reports!
    Dave

    Quote Originally Posted by mestevet View Post
    On the issue of transmission insulators, I have less certain background information, mostly just observations. Going through my collection of catenary support structures (as Kyle and Dave both know, I actually photograph such things ), I'm seeing that a LOT of the high-voltage transmission lines (the upper ones seen on PRR catenary supports typical of the 1930's electrification) that 11 seems to be the most common number of ceramics.

    However, I wouldn't say the 11 number is universal. I have a great photo of one of he supports on the 5-track Schuylkill River bridge to the east of "Zoo" that shows four upper and 6 lower transmission lines. The ones attached to the northern support (2 upper, 3 lower) all have 12 ceramic insulators. The ones attached to the southern support (2 upper, 3 lower) have 11 ceramics for the upper 2 and 14 ceramics for the lower 3. Given how many transmission lines, and that the southern/lower ones have a different support crossarm, I think some of these are power company transmission lines (PECO? - not railroad) and so perhaps the voltage and insulation requirements are different. Remember that not all the wires up on those supports may belong to the railroad, they sold right of way to power companies to co-locate transmission lines on the catenary support structures. There are locations (the electrified portion of the ex-PRR Schuylkill Valley branch is a notable one) where the catenary has been removed (and in this case the tracks too) but the supports remain, carrying transmission lines, probably those of utilities. I don't have a great photo of those, but every time I drive up the Blue Route (476) toward the Turnpike, I see them, and I've seen the same at other locations (some of the low-grade freight lines).

    Wilmington, DE, is another place where utility transmission lines are carried on the catenary supports. The utility transmission lines are supported by structures grafted onto the top of the supports. Counting the insulators on those lines, I come up with 17, and at most locations I photographed, a line was supported by 2 of those 17 ceramic insulators. I recall Marcus Hook being another area with similar arrangement (but more lines).

    Another variant was the "halo" style (my term not the railroad's) which has insulators with a metal-appearing ring (like a halo) around the top and bottom. I have photos of these with 11 ceramic insulators, but I've seen them with fewer (a photo in the PRRT&HS "Keystone" shows one with a 7 ceramic insulator). I don't necessarily understand the purpose of these types of insulators, but I have noted that they seem to show up near substations, and other points where there are line connections (perhaps they serve a sectionalizing function, I don't know).

    On my model, I just observed, for some reason I'm using 12 ceramic insulators. I don't know why I settled on that (probably 3 or 4 years ago) but that's what they are. Honestly, this is one place where I believe the looser concept of "Many" probably suffices for the actual number. I read about a study in Scientific Amerian that mentioned that humans seem to have the ability to recognize the number of objects immediately up to about 6 or 7 and beyond that the brain recognizes "Many" - you have to count them as opposed to just seeing and knowing the exact count (the reason why guessing the number of jelly beans in a jar makes a good contest, whereas putting 5 out on a table won't even stump a 4 year old). I think that concept applies to these insulators.

    Steve

  8. #18
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    In addition to substations, look for phase breaks: in PRR days there was one at Perryville, adjacent Cat. Bridge 58.68, but I don't know if that's used since the de-electrification of the C&PD, and the NECIP, Thorndale, about half a mile east of "Thorn" tower, and in the Meadowlands near Portal interlocking, I know there's been a lot of work in that area too, but I think there's still a PB there. There was also an oddball section break near Lenni on the West Chester branch, using a wood stick section between the catenary, with special instructions. I've seen it, but since SEPTA doesn't currently operate trains there, it's not in use. Supposedly, they're going to return service to Wawa, and it will be interesting to see what happens to the wood stick section there.

    A phase brake is a section where there is a change in the power supplier, and the catenary has a section that can be isolated and de-energized. This is to keep a pantograph from "shorting" between two AC supply currents that are out of phase.

    Also, see if you can observe any section breaks, places were portions of catenary can be electrically isolated from the others. These are all over, simply so that sections can be de-energized individually without disrupting power over a large area. I think there are generally two types: the "air gap" type, where, at the end where one section meets another, the wires overlap but don't touch (hence there is an air gap between them) Sometimes insulators are used to maintain the separation. Another type is the blade type (there may be a more technical term for them), but the wire transitions to a metal blade that is isolated from an overlapping parallel blade, thus isolating the sections on either side. It think these are used in places where there isn't space for the overlapping kind (tight trackwork for instance). Interlockings and yards are a good place to look for this type of trackwork, crossovers provide a "natural" point for sectionalizing to ensure that a train doesn't run into a dead section. There will also be equipment on the catenary supports to operate the sectionalizing equipment (sort of like big blade switches). Some are remotely operated, and others may be manually operated (with a locked lever at ground level on a catenary support).

    As for transmission and signal lines, there are also section breaks with those, often seen with a transformers and sectionalizing equipment on the catenary support.

    Another thing to look for are "transposition sections" or "transpositions". These are locations where transmission or signal lines swap locations. The reason this is done is to reduce mutual inductance that reduces transmission efficiency (in simple terms it "slows down" the electricity because the electrical field of one line is messing with the flow of electrons in another, and vice versa - it's actually a similar physical phenomenon to the function of windings in a motor). Sounds complicated, but simply, the transmission lines are swapped - if one was on the outside, it's swapped to the inside, and vice versa. Sometimes it's also accomplished with moving the lines from one side of the tracks to the other. The result for the catenary support structure is that the transmission supports and hangers will be in a different configuration - if they were side by side, then typically there will be a few supports where they'll split into two transmission crossarms, one line is lifted up and crosses over the other line which crosses under. In typical construction, this would be accomplished over the distance of several supports (5, 7), but it can be done in 3 or there is an example in the PRRT&H "Keystone" article where it was accomplished on one support (interesting looking configuration of transmission insulators).

    An even less recognized part of the whole catenary/transmission system are impedance bonds. Since the rails are used as electrical "return" this would provide a short circuit to signal systems which make use of current flowing between the rails (through the wheels and axles of rolling stock). Impedance bonds are boxes about a foot square, that are placed between the rails, connected by cables, which provide a filter for AC currents of different frequencies - it allows the power return to pass but blocks the signal current (at least that's how I understand it), so the signal current must pass through the rolling stock wheels to shunt the track detection circuit. If you look for them, impedance bonds are all over the place. I think that each track circuit requires one, so each track would have one placed between signals.

    Again, I recommend, for anyone interested in this stuff, get the articles from the "Keystone" (two issues, Winter '96 and Spring '97, available for $10 a piece from the PRRT&HS: http://www.prrths.com/Interchange%20...for%20Sale.pdf ):
    "Overhead Catenary of the PRR," Mike Nesladek, PRRT&HS The Keystone, Vol. 29, No. 4 (Winter 1996)
    "Electrification Photo Gallery," PRRT&HS The Keystone, Vol. 29, No. 4 (Winter 1996)
    "Of Poles, Bridges, and Substations," George L. Pitts, PRRT&HS The Keystone, Vol. 30, No. 1 (Spring 1997)

    Also used as reference:
    C.T. 290 "Electrical Operating Instructions" Revised Dec 15, 1966, The Pennsylvania Railroad
    C.T. 290 "Electrical Operating Instructions" Revised Jan 1, 1973, Penn Central Railroad
    "New York Region, Philadelphia Region, Chesapeak Region, Timetable 14, For the government of employees only," Effective October 28, 1962, The Pennsylvania Railroad

    Steve
    Last edited by mestevet; 02-27-2010 at 11:14 AM.

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