Signal Complexity

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rkcarguy
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Re: Signal Complexity

Post by rkcarguy » Thu Dec 20, 2018 11:34 am

I'm going to use 18/4 for my wiring, and these automotive relays are 40 amp ones and are pretty tough, I don't expect to have any issues with them.
As far as the sensory circuit, that's a tough one because the metal tracks are going to attract lightning and there just isn't much one can do about it. I was kicking around using some garage door sensors or the same principle(when the train shunted the rails the sensors would come on and trip the relays) between the sensory relays and the signal system, such that if the track got hit the damage would be limited to the trackside electronics and wouldn't fry all my signals.
The garage door sensors could just be mounted in a long piece of plastic pipe, capped on both ends and buried. So the signal of occupancy would get turned from electrical to optical and back to electrical again, hopefully directing the lightning into the ground instead of through the entire signal system.

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BigDumbDinosaur
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Re: Signal Complexity

Post by BigDumbDinosaur » Thu Dec 20, 2018 10:41 pm

rkcarguy wrote:
Thu Dec 20, 2018 11:34 am
I'm going to use 18/4 for my wiring, and these automotive relays are 40 amp ones and are pretty tough, I don't expect to have any issues with them.
The (physical) size and ampacity of the relays will have little bearing on their ability to survive in the operating environment. None of the components in the ABS at the Illinois Live Steamers uses such a relay as you are contemplating, and in nearly 12 years of service, not a single failure attributable to external factors has occurred.

As an aside, jacketed cable is not as good a choice as running individual conductors. Lineside wiring should be 16 gauge, with TFFN a good insulation choice, and track circuit wiring should be 14 gauge minimum, THHN being a good choice. Low voltage wire of any kind, such as control cable, CAT5 cable, phone cable, etc., is not going to do well over the long haul. Your wiring needs very robust insulation to avoid insect activity and environmental degradation. Also, the insulation has to be able to resist puncture due to momentary high voltage transients associated with switching DC relays through long circuit paths (transmission line effects).
As far as the sensory circuit, that's a tough one because the metal tracks are going to attract lightning and there just isn't much one can do about it.
Unless your railroad is devoid of trees, the likelihood of a direct lightning strike to the track is small. More likely, damaging energy will come from ground current flow and energy induced into the track by the electromagnetic pulse (EMP) generated by a nearby lightning strike. There's not a lot you can do about the ground flow, except to not intentionally bond any part of the track circuit to earth ground.

In the case of EMP-induced energy, current flow can be quite high but the actual voltage relatively low, on the order of several hundred volts, based on my experience with this sort of thing. A track circuit with low impedance that is shunted by a robust MOV at the relay end can usually tolerate the short-duration voltage impulse.

I was kicking around using some garage door sensors or the same principle(when the train shunted the rails the sensors would come on and trip the relays) between the sensory relays and the signal system, such that if the track got hit the damage would be limited to the trackside electronics and wouldn't fry all my signals.
What you are proposing is the use of optical isolation. I've yet to meet an affordable opto-isolator that I deem to be sufficiently trustworthy for this sort of application. You best bet is to do what the full-sized technology has always done and that is to segregate block occupancy detection from all other signal functions and use only dry contacts to transfer state. This is how the ABS at the Illinois Live Steamers was engineered—it is based upon real-world practice, and it works.
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rkcarguy
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Re: Signal Complexity

Post by rkcarguy » Fri Dec 21, 2018 12:43 am

BDD,

Its just too wet here, too much vegetation, for me to consider direct burial wire. I have dug up a lot of it in the past that was in very poor shape and hadn't been installed very long. I was planning on putting it inside a conduit so I can pull new wires through if needed.
My thought is to run 110V outdoor outlets to 3 places along the RR(I'm adding a serviced RV spot and another outdoor panel for a 20' container "fab shop" as part of my site plan anyway), and then have separate power supplies to minimize wires running along the track and associated voltage drop(and negate the need for any permits for HV involving the RR). Should be just two wires from each block to the distant signals that way. The 110V will also come in handy during track laying.

My thought on the relays is that they are automotive, supposedly "waterproof", and function without issue in cars for 150K miles plus. Cars are what I know best as I've been deep into nearly aspect of them for decades. If they do not function well, it's not a big loss, as I've already used several for things like adding fog lights, backup spotlights, aftermarket fuel pumps, and the like, and they can simply go in the electronics drawer for another project. Because I have easy access to free remnant metals, thinking I'll make some rectangle tube "signal cabinets" and mount the relays and power supplies inside them so they are protected and above ground.

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BigDumbDinosaur
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Re: Signal Complexity

Post by BigDumbDinosaur » Fri Dec 21, 2018 4:49 pm

rkcarguy wrote:
Fri Dec 21, 2018 12:43 am
Its just too wet here, too much vegetation, for me to consider direct burial wire. I have dug up a lot of it in the past that was in very poor shape and hadn't been installed very long. I was planning on putting it inside a conduit so I can pull new wires through if needed.
I never said anything about direct burial. :D Water and insects find their way into subterranean conduit, so you need to plan accordingly. The conduit's role is to provide mechanical protection and to make it easy to route wire from one place to another.
My thought is to run 110V outdoor outlets to 3 places along the RR(I'm adding a serviced RV spot and another outdoor panel for a 20' container "fab shop" as part of my site plan anyway), and then have separate power supplies to minimize wires running along the track and associated voltage drop(and negate the need for any permits for HV involving the RR). Should be just two wires from each block to the distant signals that way. The 110V will also come in handy during track laying.
You're not planning to use line power to light up your signals, I hope?
My thought on the relays is that they are automotive, supposedly "waterproof", and function without issue in cars for 150K miles plus.
Most automotive relays are not waterproof—you can't submerge one and expect it to stay internally dry. Also, the automotive environment is electrically benign when compared to what your ABS will experience. Furthermore, automotive relay coils consume too much power—you'll be lucky if you can even get your track circuits to work with them on anything other than a bone-dry day. Coupled with that power consumption is the intense flyback effect produced by unsuppressed automotive relay coils when power to them is cut off. Flyback can produce high voltage transients with sufficient energy to break down the insulation of inadequate wiring, as well as damage or destroy other components. This especially becomes a concern with the long wiring runs typical of ABS. Think carefully about this before going the route you are following.
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rkcarguy
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Re: Signal Complexity

Post by rkcarguy » Fri Dec 21, 2018 6:28 pm

BDD, here is the good part. While I've purchased the automotive relays and successfully tested them(see pictures), I am still open as far as how I'll do the detection. I don't want to run the relay trigger wires straight up, but rather have relays for detection that will drive the automotive relays. I can use lower voltage, more "sensitive" relays, and then de-sensitize them by adding a form of resistance into the line such that the wet track situation is solved. There are even some cool little timer delayed on-off relay modules that take 5 volts and mere milliamps to activate, will switch up to 10amps @ 30VDC, that I'm thinking I'll field test when the time comes.

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BigDumbDinosaur
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Re: Signal Complexity

Post by BigDumbDinosaur » Sat Dec 22, 2018 2:33 am

rkcarguy wrote:
Fri Dec 21, 2018 6:28 pm
BDD, here is the good part...
Good luck. I hope you are disappointed.
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BigDumbDinosaur
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Re: Signal Complexity

Post by BigDumbDinosaur » Sat Dec 22, 2018 9:09 pm

BigDumbDinosaur wrote:
Sat Dec 22, 2018 2:33 am
rkcarguy wrote:
Fri Dec 21, 2018 6:28 pm
BDD, here is the good part...
Good luck. I hope you are disappointed.
Urk! That should be "Good luck. I hope you are not disappointed." :shock:
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johnpenn74
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Re: Signal Complexity

Post by johnpenn74 » Sun Dec 23, 2018 6:14 pm

Moving the signals...

At EP on our legacy track warrant system we put cat 5 and 14awg 120vac in conduit. This has worked for several years. We have done some direct burrial but the rodents never seem to read the varmint resistent ratings on the cable.

For the new ABS block I am planning on running all the comm wires and power wires on telegraph poles just like the real guys did and have very little in the ground. See picture.

Even simple signals can work on wet conditions; just like the protototype. The test in the snow was after two continuous days of rain and everything appeared to be working ok. See earlier in the post. It did fail when it was in the middle of a down pour the night before, but I would not be afraid of wet weather issues.

Isolation will not save your signal system. The legacy warrant system at EP is completely isolated from the tracks and the power system when turned off. And yet, lightening strikes still induce enough current to burn stuff up. Not sure how the new system will survive, can't be any worse. Rails are grounded, we'll see what happens.

JP
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rkcarguy
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Re: Signal Complexity

Post by rkcarguy » Mon Dec 24, 2018 2:02 am

John, That's why I'm focusing on using easily available and replaceable components and wire in a conduit. We don't have much lightning here, but I'd expect it'll take a hit one day. I could see myself, kids, deer, etc, getting tripped up in the wires in the dark if I did poles/wires, so I had to veto that lol.

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Re: Signal Complexity

Post by johnpenn74 » Mon Dec 31, 2018 5:46 pm

Yep, The poles are larger than you think. they are 2" scale 30' poles (60 inch) and 40' poles (80 inch) this makes it high enough not to be a tripping hazzard, its about waist high.

I got a lot of push back when these telegraph poles were originally assembled. Some people just can't help but tell you what can't be done. So I put out a 2 pole test section to see what impact the deer and limbs etc would actually have. I only lost one wire of six in 5 or so years or being out there. And that was with pretty much zero maintenance. Don't forget that varmints and water can also ruin the below ground stuff as well. Sure, the modern guys do this stuff with direct burrial cable, radio comm sets and solid state PLC and processors in the signal shacks. As for me, I wanted to do it this way because I am trying to roll back time, recreate and understand what was back then, hence the system is telegraph poles and 1911 Absolute Permissive Block as close to back then as I could reasonably get. (Hmmm.... running a steam engine..... I wonder if there is a connection)

I might even hook up a telegraph signal wire and try slinging some lightening to send orders to the next station. .-- .- - -.-. .... / - .... .. ... / ... .... .. -

CTC next, maybe....



JP
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Logging meets that actually move logs

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ChuckHackett-844
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Re: Signal Complexity

Post by ChuckHackett-844 » Tue Jan 01, 2019 2:43 pm

johnpenn74 wrote:
Wed Dec 12, 2018 10:16 pm
If you enforce a one-train-per-block rule your railroad will get constipated on a busy day as engineers stand at red signals waiting on a slow-moving train up ahead to clear the block.
What? that's just flat out wrong. If you look at ANY track that has two way traffic and capture the flag signals (White Creek, Eaglepoint, CStp&P, Mill Creek to name a few of the biggest ones out there) all that is allowed into the block is one train at a time. Sure you can manually section, but that is the exception not the norm.
I find quite the opposite. At many (all?) tracks I have been to that have signals there is a lot of "following as second section" (encouraged or not). There are a lot of guys that have short trains (box cabs, etc.) and they want to 'run' so two or more of them will get together and follow each other around quite happily as multiple sections. (this assumes that the following engineers are diligent in maintaining separation)

This all works well on automatic systems that can handle it but sometimes falls flat when 'slap signals', etc. are in use because, in those cases, it requires and understanding between the trains as to who is going to capture the block and who is going to release it.

Also, a given railroad has a theoretical maximum number of trains that it can handle at a given time (limited by siding availability, length of blocks, etc.). Smaller trains running as 'multiple sections' is actually a benefit during a large meet because it reduces the number of 'trains' running and frees up blocks for reversal sooner (assuming that the 'multiple section' isn't too long for the available sidings).

My system is quite happy to allow trains to follow each other as second sections and act as one train without coordination between trains (i.e.: a second section can merge and diverge at any time even within a block).

At Central Pasco and Gulf Railroad (Florida) we encourage trains to not follow as second sections because it provides more meet-and-pass opportunities to add realism but we specifically allow it as long as engineers know that separation is their responsibility.
johnpenn74 wrote:
Wed Dec 12, 2018 10:16 pm
The real congestion is a result of unmanaged traffic flow. People going where they want when they want with out any multiple passing, priority overtaking, or means to coordinate the flow.
In my experience engineers want to run a verity of paths without the signal system getting in the way unless it is to prevent conflicts/collisions. A good signal system should help with traffic flow, not get in its way.

This is the reason I have spent so much time implementing "auto dispatcher" logic in the system that coordinates flow between and across multiple blocks as opposed to just acting strictly on 'block occupancy'. Note: in my system this is all done by configuration parameters - no extra wire needed.
johnpenn74 wrote:
Wed Dec 12, 2018 10:16 pm
I'll solve that problem next year... :-)

JP
I'd be interested in hearing how you will accomplish that without requiring trains to be 'dispatched'.
Regards,

Chuck Hackett, UP Northern 844, Mich-Cal Shay #2
Owner MiniRail Solutions (http://www.MiniRailSolutions.com)
"By the work, One knows the workman"

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johnpenn74
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Re: Signal Complexity

Post by johnpenn74 » Wed Jan 02, 2019 3:41 pm

Why have the signals at all if you are sectioning....

The signals are there to prevent three things, front end collisions and rear end collisions and derailments from too much speed in a route change. So I have to ask, if you not going to stop at a red signal for the occupied block in front of you, or start slowing because you have a yellow approach, then what's the point? Basically operators are just blowing off the very devices that were put into service to help protect the system in the first place. So signals are just there to be pretty and ignored?

I just don't get it. So many people at the clubs have a mentality of "This is a hobby so what can I get away with". Signals are designed and placed to improve safety, too bad if that's inconvenient. Maybe after we plow enough cabooses people will get to the point to ether slow or obey signal protection on a blind curve.

I guess the real difference is where and what you are operating. If you are running in the flats of Florida with a diesel and 2 cars made from Aluminum maybe you can stop on a dime. But is that our safety plan?

At EP our mountain division is 2500' at 2% grade. And ignoring braking and safe stopping distances is just unsafe.

JP
John Pennington

Logging meets that actually move logs

Project
2 Mich-Cal Shays
Allen 4-4-0 Narrow Gauge Conversion
Two Reading A5a Camelback 0-4-0
USRA 0-6-0
Clishay
4 Western Wheeled Scraper NG Dump Cars
N&W 4-8-2
ICM 2-10-2
4 Modern Stake Cars
L&N Caboose
4 Big Four Conversion Gondolas

Like I'm actually gonna build all this stuff :-P

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