question on buss wire connections


frank@...
 

HELP!!

I am a newbie and have a question about how to properly connect and layout buss wires when there are electrical blocks or districts on the layout. I have two tracks on my layout and a buss wire servicing each track via feeder wires to the buss. I have set up 2 electrical blocks on each track using insulated rail joiners for a total of four electrical blocks or districts in the layout. My question has to do with the buss wires and whether or not I need to create separate buss wire lengths for each of the four electrical blocks on the track? If so, I assume that I would need to cut the buss wires at the appropriate locations (to end up with 4 separate buss wires in total)  so that the length of buss each wire is consistent with the track length for each block? Is this correct or is it unnecessary to do this?

Frank


JoAnn Donaldson
 

Frank,
   My small layout is divided into four Electrical Zones. Each is feed from a output of the PM42 Power Distribution. This so that if I short one Zone it does not affect the other three. Also I have a small yard in the front and a small hidden yard on the back. There I have each length of yard track with it's own buss feed. I use power routing switches. This allows me to keep all the tracks powered. I also have feeders on track that lead to the yards and leaves the yard. So the front zone has three on the yard tracks and one each entering and leaving for a total of five feeders to that Zone Buss. So be careful of which switch you use. I prefer the Power Routing Switch. The problem comes if your moving a train on yard track and need to move another Engine on a parallel track. If the switches are pointing to the track that the train is on you can not operate an engine on the parallel track unless it has it's own feeder.

On Sunday, March 27, 2022, 09:58:28 AM CDT, frank@... <frank@...> wrote:


HELP!!

I am a newbie and have a question about how to properly connect and layout buss wires when there are electrical blocks or districts on the layout. I have two tracks on my layout and a buss wire servicing each track via feeder wires to the buss. I have set up 2 electrical blocks on each track using insulated rail joiners for a total of four electrical blocks or districts in the layout. My question has to do with the buss wires and whether or not I need to create separate buss wire lengths for each of the four electrical blocks on the track? If so, I assume that I would need to cut the buss wires at the appropriate locations (to end up with 4 separate buss wires in total)  so that the length of buss each wire is consistent with the track length for each block? Is this correct or is it unnecessary to do this?

Frank


frank@...
 

Thanks Joanne for the response and comments. I don't have power routing switches so I am not sure if your situation is comparable.

I am still confused about whether or not I need my buss wire lengths to be consistent with the electrical blocks on my track. It sounds like your tracks are synced up with your buss wires in terms of length but I am not sure i am getting that right??. Also, if you do have the track and buss wires synced together (same start and end point), I am still not clear whether or not that is necessary.?

Thanks again for any clarification.

Frank


Jerry Michels
 

Frank, you wrote "If so, I assume that I would need to cut the buss wires at the appropriate locations (to end up with 4 separate buss wires in total) so that the length of buss each wire is consistent with the track length for each block? Is this correct or is it unnecessary to do this?" You do not need to have buss wires the same length. This has been proven on our layout for years and years. Some of our busses are about three feet and others are nearly 30 feet. We add feeders to a buss every three feet in a given block as a minimum. Some situations require the feeders at less than three feet, but that is rare Three feet was chosen because it is the typical length of the code 83 flex track, and the feeders are located at the middle of the three-foot section of track. I would not recommend trying to feed a yard or multiple sidings through a single feeder. Solder a minimum of one feeders per track, and do not rely on power-routed turnouts for efficient power delivery. Power-routing depends on mechanical contacts that can fail. Not always fail, but can fail due to many factors, including simple age. Hope this helps.

Jerry Michels
Amarillo Railroad Museum


frank@...
 

Thanks Jerry:

Yes, I understand that the buss wires can be of different lengths and that the feeders should be every 36 inches or so and perhaps closer where there are turnouts. My question relates to whether each electrical block on the track must have its own buss line (that contains all the feeders for that section and no feeders from other sections) that in turn connects separately to the controller. It seems to me that if you have to troubleshoot a problem, this must be the situation so that each section can be properly evaluated separately. I guess I will find out the answer if and when there is a problem and I have to evaluate each section individually.??


John Bishop
 

One feeder per rail piece (ie, between rail joiners) is what I have been advised, and do. 

 For sections I want to be able to turn off, I run a parallel bus the length of the block, which can be turned on and off with a DPST switch to the main bus. I have done this for sidings and passing tracks. That way you can fool with the trains in those locations without causing a shortl
 Also my layout is point to point (at least for now), and I have the equivalent of a switch to cut the main bus part way through to isolate the two halves which I have found is handy to isolate problems.

Hope this helps.

John Bishop



On Monday, March 28, 2022, 12:40:46 PM PDT, <frank@...> wrote:


Thanks Jerry:

Yes, I understand that the buss wires can be of different lengths and that the feeders should be every 36 inches or so and perhaps closer where there are turnouts. My question relates to whether each electrical block on the track must have its own buss line (that contains all the feeders for that section and no feeders from other sections) that in turn connects separately to the controller. It seems to me that if you have to troubleshoot a problem, this must be the situation so that each section can be properly evaluated separately. I guess I will find out the answer if and when there is a problem and I have to evaluate each section individually.??


frank@...
 

Thanks John, for the response and comments. I didnt think of running a parallel bus line to cover specific sections and set up different blocks. Good idea! I will consider that even though I hate doing any additional wiring!

Frank


Don Vollrath
 

Frank: breaking up the buss wires to correspond to rail sections is one of the first steps in being able to detect occupancy for signaling or easy troubleshooting. Use multiple rail feeders as you have said. But the physical length of each buss, or the path from track feeders to a DCC buss distribution center (booster or other) doesn’t need to be the same distance or path as the rail itself.

We are talking about feet or meters here, not hundreds of miles. (Unfortunately this leads to the endless discussion about long buss leads, twisted buss wires, no circular paths and the use of R/C snubbers when buss runs get longer than 30 feet or so)

DonV


Jim Zarnick
 

Frank,

 

There are multiple ways to make this work electrically.  Here’s what I’ve done…

 

I have 2 power districts, each with it’s on NCE power supply.

Each power district has 3-4 subdistricts, each with their own circuit protector.  12 gauge bus from the power supply to the subdistrict circuit protectors (NCE EB1s).  From the circuit breaker their a miniatronics distribution panel with 2 16 gauge wires running to each block.  I chose to double insulate each rail of the block for the exact reason you mentioned, the ability to isolate for troubleshooting.  

 

My rule with feeders is every piece of track is soldered to something, either feeders or the adjacent track.  Every piece of flex track has its own feeders, every switch has its own feeders.  I soldered rail joiners in 2 situations only: if I had a short piece of track (very short) or only large curves I soldered the rail joiners so the flex track was less likely to want to straighten out at the ends. 

 

Feeders are 20 gauge solid and very short, 2-3 inches.  All feeders are spliced into the bus with scotchlok connectors.

 

Now go have fun!

 

From: w4dccqa@groups.io [mailto:w4dccqa@groups.io] On Behalf Of frank@...
Sent: Monday, March 28, 2022 3:41 PM
To: w4dccqa@groups.io
Subject: Re: [w4dccqa] question on buss wire connections

 

Thanks Jerry:

Yes, I understand that the buss wires can be of different lengths and that the feeders should be every 36 inches or so and perhaps closer where there are turnouts. My question relates to whether each electrical block on the track must have its own buss line (that contains all the feeders for that section and no feeders from other sections) that in turn connects separately to the controller. It seems to me that if you have to troubleshoot a problem, this must be the situation so that each section can be properly evaluated separately. I guess I will find out the answer if and when there is a problem and I have to evaluate each section individually.??


Martin Piech
 

Don,

What are R/C snubbers? What is their purpose on a layout and how are they used?

On Tuesday, March 29, 2022, 09:16:32 AM EDT, Don Vollrath <donevol43@...> wrote:


Frank: breaking up the buss wires to correspond to rail sections is one of the first steps in being able to detect occupancy for signaling or easy troubleshooting. Use multiple rail feeders as you have said. But the physical length of each buss, or the path from track feeders to a DCC buss distribution center (booster or other) doesn’t need to be the same distance or path as the rail itself.

We are talking about feet or meters here, not hundreds of miles. (Unfortunately this leads to the endless discussion about long buss leads, twisted buss wires, no circular paths and the use of R/C snubbers when buss runs get longer than 30 feet or so)

DonV





Jerry Michels
 

Frank, you wrote "My question relates to whether each electrical block on the track must have its own buss line (that contains all the feeders for that section and no feeders from other sections) that in turn connects separately to the controller. It seems to me that if you have to troubleshoot a problem, this must be the situation so that each section can be properly evaluated separately."

I am not sure if I am understanding you completely. At the Museum we run a pair of wires from a given power supply ( say an Digitrax DB220) to a PM42, which splits the power into four separate outputs, and each of those outputs powers a separate buss. Think of it as power distribution, one pair of wires from the power supply to four pairs out of the PM42 and each pair powers a buss to however many feeds are needed per block.


JoAnn Donaldson
 

I too use an PM42 to split my small layout into four zones. I did this so that if one person is operating on the front side and accidentally short the track it doesn't shut down the entire layout. I also added feeders to all of my parallel tracks. All of my turnouts are power routing but I find that sometimes in a yard setup, you need power on the tracks that is not part of the mainline tracks.

JoAnn Donaldson

On Tuesday, March 29, 2022, 09:02:34 AM CDT, Jerry Michels <gjmichels53@...> wrote:


Frank, you wrote "My question relates to whether each electrical block on the track must have its own buss line (that contains all the feeders for that section and no feeders from other sections) that in turn connects separately to the controller. It seems to me that if you have to troubleshoot a problem, this must be the situation so that each section can be properly evaluated separately."

I am not sure if I am understanding you completely.  At the Museum we run a pair of wires from a given power supply ( say an Digitrax DB220) to a PM42, which splits the power into four separate outputs, and each of those outputs powers a separate buss. Think of it as power distribution, one pair of wires from the power supply to  four pairs out of the PM42 and each pair powers a buss to however many feeds are needed per block.






Don Vollrath
 

Martin asked about R/C snubbers, their purpose and use.

The purpose of an R/C snubber is to terminate, or “snub”, the unwanted transmission line effects of the DCC wiring distribution system. These effects include reflections and or ringing of the rather fast rise and fall of DCC signaling due to rapid polarity switching of the booster, wiring length, and wiring style ( random, twin lead or twisted pairs). Some loco decoders are more sensitive to signal distortion than others. Typical interference effects include noticeable locations on the layout where a loco does not respond to DCC throttle commands.

It many cases (larger layouts) it is desirable to place an R/C snubber/terminator (a resistor in series with a capacitor) as a load at the far end of the DCC power wiring path away from the booster, when total length is greater than 30 feet or so (not overly critical) but located so that any current drawn is not measured by any track current occupancy sensor.

It turns out that the characteristic impedance of typical out and back model railroad wiring is 100-200 ohms at the frequencies of interest. So using a 150 ohm resistor is a good compromise. And using a capacitor of 0.1 uFarad (non-polar, 50 V or more) in series with the resistor to reduce the loading of the resistor during most of the DCC cycle is ideal.

DonV


rrmaven
 

Don-  thanks for the excellent description of function and application of snubbers.
    Dan Lee   San Jose, CA

On 03/30/2022 6:56 AM Don Vollrath <donevol43@...> wrote:


Martin asked about R/C snubbers, their purpose and use.

The purpose of an R/C snubber is to terminate, or “snub”, the unwanted transmission line effects of the DCC wiring distribution system. These effects include reflections and or ringing of the rather fast rise and fall of DCC signaling due to rapid polarity switching of the booster, wiring length, and wiring style ( random, twin lead or twisted pairs). Some loco decoders are more sensitive to signal distortion than others. Typical interference effects include noticeable locations on the layout where a loco does not respond to DCC throttle commands.

It many cases (larger layouts) it is desirable to place an R/C snubber/terminator (a resistor in series with a capacitor) as a load at the far end of the DCC power wiring path away from the booster, when total length is greater than 30 feet or so (not overly critical) but located so that any current drawn is not measured by any track current occupancy sensor.

It turns out that the characteristic impedance of typical out and back model railroad wiring is 100-200 ohms at the frequencies of interest. So using a 150 ohm resistor is a good compromise. And using a capacitor of 0.1 uFarad (non-polar, 50 V or more) in series with the resistor to reduce the loading of the resistor during most of the DCC cycle is ideal.

DonV


Jerry Michels
 

Don, This may have been addressed before, but won't a snubber appear as a load to a current-sensing detector? Jerry Michels


Steve Haas
 

Jerry Michels inquires:

"Don, This may have been addressed before, but won't a snubber appear as a load to a current-sensing detector?"

Jerry,

It is something that needs to be considered but Is easily managed.

Mark Gurries wrote a section on the Wiring for DCC web site that discusses this and has examples:

https://www.wiringfordcc.com/track_2.htm#a52

Hope this answers your questions!

Best regards,

Steve

Steve Haas
Snoqualmie, WA


Don Vollrath
 

Yes… that’s why I said (the R/C should be) “located so that any current drawn is not measured by any track current occupancy sensor. ”

DonV


Jerry Michels
 

I know this is late to respond to, but I hope to get some more information. Don, I understand what you wrote, but I am not sure I made myself clear. Suppose I have a three-block layout. Block A connects to Block B then Block C then Back to Block A. So if I want to sense current draw in each block to run a signal system, R/C cannot be used? So does this situation preclude the need for R/C or do you just have do do without?

Thanks,

Jerry Michels


Steve Haas
 

"I know this is late to respond to, but I hope to get some more information. Don, I understand what you wrote, but I am not sure I made myself clear. Suppose I have a three-block layout. Block A connects to Block B then Block C then Back to Block A. So if I want to sense current draw in each block to run a signal system, R/C cannot be used? So does this situation preclude the need for R/C or do you just have to do without?"


Jerry,

Again, I refer you to the following Wiring for DCC page: https://www.wiringfordcc.com/track_2.htm#a52.

Both examples given on that page illustrate the use of an R-C filter with block detection (in this examples, BD-20's). In fact, both illustrations are for three blocks (1, 2, and 3); just rename them to your blocks "A, "B", and "C" as in your inquiry, then take the left of block1 end and extend it clockwise to the top center of the drawing, then take the right end of bloc3 and extend it counterclockwise up and around to meet the end of block1 (gaps in rails and buses there), and you will have exactly the situation you inquire about.


The important thing to remember when dealing with R-C filters and current sensing detectors:

The RC-Filter is not placed between the BD-20 and the section of track it is detecting occupancy. This is illustrated in both of the diagrams.

Best regards,

Steve

Steve Haas
Snoqualmie, WA

















Thanks,

Jerry Michels


Don Vollrath
 

Jerry: Steve has given you the correct answer. Look at the diagrams. There is a sub-buss for each of the occupancy sensed blocks with multiple track feeders as necessary. And a DCC main bus supplying power to the sub-busses. Place an R/C snubber at the far end of the main DCC bus.

DonV