Preventing DCS from starting all engines at full speed after a short circuit occurs

[du-bousquetaire]

Hi there:

I just wanted to ask all the electronic wizards out there who understand all this much better than I, if there is a way to prevent all engines on the pike not on an isolated siding from starting at full blast as soon as a short circuit occurs. However carefull I can be about this, these tend to still occure now and then.  And beleive me, I have spend  a considerable amount of time making all possible improvements to prevent it from happening . But human error is unfortunatly common and these do occure from time to time... Is it just that I havent found the magic formula? Can it be prevented from happening?

I find that this is the main drawback from using DCS or developping it's use. And I find the manufacturers criminal in not having taken measure to prevent this from happening, from the start. it may not be so much of a big deal in the smaller scales but in gauge one it really wreaks havock in a yard when it happens.

 In my case I have an outdoor pike with a branch to an indoor terminal, an almost ideal set up: In case of a downpour flip the switch lever and run your trains to safety indoors. Yea, it used to be great, untill DCS. Now I have had to rewire a second time the yard: First each track  used to get track current through the switches, with DCS I had to rewire all tracks so they got trackvoltage at all times. Then I installed togles to cut out tracks that hold an engine so that it won't shoot off,  if there is a short circuit (What usually happens is two engines start off towards the yard throat then crash into each other! Result: straightening up the grabs on the pilot and doing some paint touch ups every time.

 Now my procedure is to shut off unwanted engines (unless they are about to be employed within minutes). Then, if I need to call them, I first call the engine up on the handheld, then when it is on the screen, I flip on the togle and immediately shut down. Then I start the engine up again and it goes and does what it has to do. I have found that the read button doesn't do anything at all except add to the pending disaster.

 Is there some Eureka Idea I have missed?

 This procedure works but is a bit fastiduous and if I could solve this safety problem I would be real glad as if a short occurs outdoors, I may not be aware that it provoqued the kind of unwanted meet at the yard throat indoors that I just described above. (although now it is one of the first thing I check...) It once made one of my engines burn out two traction motors as the A unit in the A-B-A lash up stalled on the switch (creating a short) but the other A unit near the rear kept running burning out the two traction motors! This cost me more than the cost of the engines to repair. I guess with battery power this would be solved, but how long does a A-A lash up last on batteries before recharging? Can't a TIU be programmed to send out a watchdog signal after every short? It seems that with todays electronics this should be an easy matter to solve. And what an improvement this would be...

Well hope we can solve this one one of these days, as in gauge one it is a real issue.

[Rayman4449]

Hi Simon,  I'm sending you an email because from our last conversation a year ago I recall you had changed power supplies and had fixed the short problems with your switch points and the J&M Heavyweights shorting out the layout.  I recall other items/questions still outstanding that I was helping with that I'll reply to.  I recall before not fully having a clear picture of what was going on during these shorts as having a momentary short should not be impacting the layout voltage and even it power is lost for a split second you should not be having this issue.  As I remember before there is more going on here that needs to be troubleshooted and just need to figure it out.

[SteamPower4ever]

Hmm ... we have occasional power-downs on the club layout.

Does this happen with PS3 decoders running DCC ?

Jens

[Rayman4449]

I haven't had time to reply to this thread till now but I have spent time chatting with Simon to get a full picture of exactly what is going on.  Here are the details of what is going on in this particular case along with my recommendations on how to correct:

 

Issue:

- Shorts were being experienced that when they occurred were causing engines to miss the watchdog signal when voltage is restored to the layout.  This is has caused situations where engines on the staging tracks inside the house that are out of sight and view from outside to power up and collide causing damage.

 

 

Layout:

- Running track power with TIU connected in 'Normal mode' (not passive) using Fixed 1 and Fixed 2 channels.

- Using a Bridgewerks throttle power supply

- Layout has two ovals with a set of staging tracks inside house (away from view outside) and siding outside.

 

 

Root problems:

- Shorts that are severe enough to cause the voltage to collapse on the layout. 

- Fuses weren't blowing and instead were relying on the power supply circuit breaker 

- Engines powering up on the staging tracks after power restored either due to 1) not seeing the 'watchdog' signal sent by the TIU or 2) the watchdog signal not being sent for some reason.  Because they are out of sight if this happens it can cause big problems as it can go unnoticed for a period of time.

 

 

Shorts:  (Causes of the Shorts)

- Shorts are due to the fact that the switches/turn-outs (which are custom made) have both switch-points that flip to the same polarity.  When the switch is turned to the right, both switch points will have right side polarity.  When switched to the left, both have left side polarity.  What is happening is when engines enter the turnout with the switch set to right for example, the backside of the left wheels are sometimes making contact with the left switch point rail (that isn't needed or used in this case) and creating a heavy short.  This is why the shorts are occurring with such regularity.  This is also a reason why I and would say most here in the U.S. haven't seen this as such a major issue.  In the U.S. most of our switches are made my major manufacturers and the switch points always maintain their original polarity, which ensures these types of shorts do not occur.  This diagram shows how the polarity changes on the custom switch as it is changed from side to side.

 

 

 

My Recommendations:

My core recommendation is to implement a fix at the switch-level to either eliminate the shorts or reduce their severity.

 

- Correct the source of the shorts so they do not occur any more:  

       - Response/Answer:  Definitive no, is not willing to change how the switches are wired so other options have to be looked at.

- Reduce the severity of the shorts so they don't cause the voltage on the entire layout to collapse/drop.

        My Suggestions:

               - Polyfuses:  Use Polyfuses (which are a resettable fuse) between the points (or in other locations) so shorts against the opposing switch point will be capped at a much smaller amperage and thus prevent voltage collapse

                  but also protect the engine wiring.  Repsonse/Answer:  No, unwilling to change how they are wired on this as well.

 

Next suggestions:

- Fuses:  (#1 and the most critical item) Use a fuse more closely rated for the loads being used on the layout. (Do this regardless if polyfuses or switch changes are implemented or not)  

               Use the Ammeter on the power supply as a guide but, in most cases a 5amp fuse is what should be used.  If you need more, move to a 7.5 amp fuse then 10amp.  

               The fuse should always blow before the circuit breaker trips on the power supply.  If the breaker is tripping I recommend moving down to a slightly smaller fuse.  

               This recommendation is important as having long duration, high amp shorts risks damaging wiring within the engine.  It also can damage the TIU channels over time (which may have already happened in this case)   **Bottom line for those reading this after the fact, this single item, using an appropriate fuse would have prevented any and all malfunction/damage as a result of the shorts**

- Toggle switches for the staging tracks indoors:  For staging tracks with engines that are indoors and out of sight when outside, I highly and strongly recommend adding a toggle switch to the negative rail

               for each of the staging tracks.  When engines are not needed, flip the power off and only turn on when actually needed.  This is something I do for my own staging lines as I never want my engines

               that are out of sight left on the track with power applied as you just never know what can happen.  

               If toggle switches are used, see the following article on tips on toggled sidings:

                    - http://www.rayman4449.com/DCS_Tips.htm#How_to_add_an_engine_to_the_layout_when_other_engines_are_already_powered_and_running 

- Add DCS Remote Commander box to Staging tracks:  Whether or not if toggle switches are added, the adding of a DCS Remote Commander box to the staging tracks would generate their own watchdog signal if power is cut and restored as in a short.  This might help ensure they remain in place.  I still recommend adding toggle switches to keep them powered down regardless if Remote Commander box(es) are added or not.  The best setup is to have toggle switches and the RC boxes which is what I use.

- Do not power TIU with Aux power supply:  A TIU can be powered with an Aux power supply or it can get power from the TIU via Fixed 1 port.  If you power the TIU via the Aux power supply, if you cycle track power the TIU does not resend the watchdog signal because it doesn't power down and power backup.  It remains powered up by the Aux power supply.  So it is always best to make sure you use the Fixed 1 channel on the TIU only and don't use an Aux power supply.

 

 

Other recommendations:

- Run TIU in Passive Mode:  To protect the TIU from future high amp shorts and to eliminate the Amperage limit of 10amps per channel, run the TIU in Passive mode.  

  See here for more info:  http://www.rayman4449.com/DCS_Tips.htm#Use_of_TIU_to_provide_signal_to_track:__Normal_vs_Passive_mode

 

 

 

Final Comments:

- I'm not certain in this particular case if the TIU isn't resending the signal or if the signal is being resent and the engines are just missing it.  Given that it doesn't sound like they are missing the signal when first powered up, it sounds like there is an issue with either how the engine boards are reacting to the loss of power or the TIU, it's hard to say.  I would have to replicate these shorts on my layout to study the TIU and board reactions to try and get an idea if the issue is based on just how equipment is responding or if it could be due to something damaged/faulty.  At this point are unwilling to subject my equipment to such severe shocks and in the end don't think it's necessary as if the above recommendations are implemented it will not only resolve the root problem of the shorts but also reduce their severity.  The fuses will better protect the equipment and add another line of protection as an emergency cut off if a serious electric event occurs on the layout.  Running the TIU in Passive mode will ensure the TIU is always protected in all conditions.  As I indicated, I don't have these problems and have taken steps to eliminate even the smallest of shorts at my switches like for instance: I removed the power to my Aristocraft #6 switch frogs to eliminate even the smallest shorts that can occur from failed switch micro-switches or running through a switch backwards.

 

Even if only some of the recommendations are implemented future problems can be eliminated.

 

**But the key takeaway for those reading this after the fact is, this is why using an appropriate value fuse between your power supply and layout is so critical.  In this case, using appropriate value fuses would have blown when shorts occurred and thus preventing any and all subsequent malfunction and damage.  If you have recurring severe shorts as in this case, they MUST be addressed.**   

 

Raymond

[Rayman4449]

I wanted to share that I now have the new PS3 boards to upgrade existing PS2 engines.  This is relevant to this thread in that PS3 engines do not start up running under analog mode if they have somehow missed the TIU initial start-up signal.  So while I do recommend trying to address the underlying issues causing the voltage collapse on the layout, upgrading to PS3 would eliminate this problem of unintended running under analog mode.  This brings the behavior of how engines operated under AC power now to DC (as this is how the PS2 engines operated under AC power).

 

Please visit my website and email me if interested.

 

I have also updated the "Protosound 3 thread" here:  www.gscaletrainforum.com/index.php?/topic/429-protosound-3-whats-new-with-mths-ps3-vs-ps2/ 

 

PS3 will be a worth while upgrade for us in G scale.  

 

 

To recap the key benefits for G scale/One Gauge:

 

  - Significantly improved signal processor on the engine board.  (If you have had signal/communication issues in the past on your layout, this should resolve it or significantly reduce any issues.  Best results, run PS3 with Rev L TIU)

        - This is relevant for G scale because of the much larger size of the layouts and conditions faced outdoors.

  - Improved audio amplifier for higher sound quality

  - PS3 sound files:  Can now load these to your engine which have greatly enhanced sound quality.

  - No more missed TIU start up signals:  Engines stay put and will not move if they miss the TIU startup signal on initial power up.  (Applies to DC power operation)

         If you had engines missing the signal in the past moving to PS3 should eliminate or greatly reduce this happening.

  - Eliminates the need for the polarity switch on the engine as the PS3 board is no longer polarity sensitive.  

  - Eliminates the need for the on-board rechargeable battery pack (the only maintenance item you had on the engine)

  - Can now run under DCS or DCC.

[du-bousquetaire]

Hi Raymond: I just read this today (febuary the10th) and hadn't seen it when you made the last two posts... The fact is, this was a very usual way to cable pointwork in the days of scale rail fans, building their own trackwork, a thing very common in model railroader of the 1960s. So I am surprised that others havn't had this issue also. I guess most in G scale dont make their own track.

 

One important point though should not be overlooked  and it explains why I wont change things for now: For one with this type of pointwork it is nearly impossible to insulate them the way commecial pointwork is. I have done it indoors on one of my threeway point using a small and thin piece of styreen inside the frog, but it is too fragile for outdoor use. And my GG1 has skates so wide they short out going over that frog which is why the GG1 on that siding is now Verboten! (Don't forget that I have been running electrics in analog mode on this pike since the 1980's without any prior problems with shorts except when an engine engaged onto a point that wasn't set correctly. It even provided a certain amount of head on colision insurance! - Not useless in gauge one).

 

Two I have given a great deal of clearance between the switch rails and the wing rails so that there should not be any shorts with equipment with a correct back to back. Some of the issues I had with the J & M coaches came from some wheels that were lose on the axles and whose gauge therefore was shorter than correct 40mm. Back to B. As these were six wheel truck, they didn't derail and it took me some time to realise this was happening, because it was the center wheel (Actually it was on a fall evening running session, when the light got so dark, I saw the sparking and then took a closer look at the car in the shop).

 

Three I have installed toggles in the inside (out of sight) yard a long time ago because and right after of the incident which burned out the two motors on my F3. It is now standard procedure.

 

Otherwise your analysis is quite correct and I have descided to try wiring everything in Passive mode before this springs running sessions resumes.

 

 How can older engines get a PS3 upgrade? Without changing the boards.

[Rayman4449]

The PS2 boards in the engines have to be replaced to upgrade to PS3.