Power Districts w/Separate Power Supplies Negatively Impact TIUs?

Junior,

1. Am I putting my TIU at risk of premature failure when an engine or powered rail car (for example a lighted passenger car) temporarily (as in when I'm running my trains) bridges an insulation point separating two track blocks/power districts?

No.

2. And is there more of a risk if I inadvertently park an engine or powered rail car across an insulation point separating two active/powered track blocks/power districts?

No.

One caveat to the two answers above. Experience has shown me. personally, that any time a command is issued when an engine's power is straddling tracks connected to different TIUs, there is some possibility of a delayed response and/or an error message.

This may vary in severity depending upon the individual TIUs involved, from no issue at all to a few seconds of delay accompanied by an error message.

First off, when the train transitions between power blocks that are on different TIU channels the train effectively bridges the two channels and you lose signal and control. Your best bet is to run 1 train let channel and minimize the places where you cross from one channel to the other channel. A TIU channel can handle a ton of track so if you have 3 loops of track and s yard, use one channel per loop and the last channel for the yard 

Second, when you bridge between two power districts you allow the train to be exposed to twice the amperage of the transformer channel. This also messes up over current protection as circuit breakers aren’t setup to operate that way

Matt,

First off, when the train transitions between power blocks that are on different TIU channels the train effectively bridges the two channels and you lose signal and control.

As I posted above,"...any time a command is issued when an engine's power is straddling tracks connected to different TIUs, there is some possibility of a delayed response and/or an error message." However, control is typically not "lost". What happens is that the engine receives two instances of the same command and the remote may display an error message and/or experience a delay while the engine sorts out the command and/or the remote sends the command again.

This may be exacerbated if the train contains cars with two sets of pickup rollers, such as are most often found on passenger cars, since these will also bridge the two track blocks connected to two different TIUs. Again, the severity of the problem may vary considerably.

Second, when you bridge between two power districts you allow the train to be exposed to twice the amperage of the transformer channel. This also messes up over current protection as circuit breakers aren’t setup to operate that way

This isn't any kind of a problem at all.

Amperage availability is not an issue unless there's a short circuit that actually draws more amps than the circuit breaker or fuse is prepared to handle. Regardless, if there is an overcurrent situation, it matters not if there are 10 amps or 20 amps available. Regardless, the circuit breaker or fuse would simply operate in the way that it's supposed to do, i.e., by cutting power to the track.

Your best bet is to run 1 train let channel and minimize the places where you cross from one channel to the other channel.

Junior, the OP, has designed his layout using Power Districts, where each track block has a different power source such that multiple trains can better utilize all of the power available from all 4 of the layout's transformer while running on a single loop. Since he is only using one TIU, the entire problem of multiple TIUs and trains straddling power districts, all of which belong to one TIU, is moot. 

To be clear to everyone, I am running a single TIU were all 4 channels are Fixed. But each channel is fed by it's own PW ZW.

I know it's overkill but these old ZWs heat up quick when you put any kind of load on them....hence my using multiple ZWs. 

And yes....I know newer engine draws less power than the old postwar engines do. But I run a Lionel Steel switcher that's TMCC controlled and that little guy buy itself can draw 2-3 amps.....seriously!

BTW....I run at 17 volts (not that it makes a difference) because 2 of the ZWs can't maintain a stable 18 volt setting; they vary too much. I checked the rollers and they're all in good shape and the coils are clean. But.....🙁 every one of the ZWs had their coils sanded.

Anyway....here's a few pics of the layout and control panel that I hope you'll enjoy.

It appears to me that there are two weak links in your design that could put the TIU at risk.

1. The management of the output voltage of the ZW s is critical. If that varies between two power districts, the potential of "transformer bridging" increases. That can damage engines, lighted cars and possibly the TIU when crossing power districts. Careful management of the output is a must. You do that, but Murphy's Law could come into play.
2. Could you describe the "resettable fuse" that you are using and it's physical location?  Thermal devices have delays before they break a circuit. The voltage and amperage could exceed the TIU's limits, however briefly, and possibly put it at risk. The fuse in the TIU is a fast blow, which should provide protection. The TVS that you have in place is extra insurance.

The design of your power supply indicates that you are aware of and have managed the risks. Always check your meters before operating the layout and hope that Murphy doesn't visit. Keep spare TVS on hand for the TIU outputs and change them after a big sparking derailment or on a periodic interval. It's difficult to determine if they are still intact.

Barry addressed the DCS signal concerns.

Nice layout! Have fun!

Thanks Moonman 😀

The "resettable fuses" are 7 amp circuit breakers. I was initially using 10 amp breakers but they never tripped for a derailment before I was able to shut the power off. The 7 amp breakers always trip before I can reach the main power switch.

I was looking for something faster (like magnetic circuit breakers) but they were cost prohibitive at the time. I may need to revisit that option.

I am seriously considering replacing the PW ZWs with Lionel's 180 watt Powerhouse power supplies.

I'm hoping that change would provide a more stable voltage stream and require less monitoring on my part. And it's my understanding that the circuit breaker in those are really fast.....a definite plus.

But I know I will still have to manage where I park trains so that they don't straddle an insulation point between to power districts.

The PH180 has one of the best, if not the best circuit breaker of any of the brick transformers.  I swear by them, they are great!

Hey GRJ.....Thanks for confirming re. the PH180 circuit breakers. 

Do you have experience with using multiple PH180s? Are the voltage outputs spot-on to each other?

If the power is from the same phase and same input voltage, the output voltage will be the same.  That assumes the same load as the transformer voltage will vary with load a volt or so.

You should experience no significant issues using multiple PH180 transformers, we've been using them for years on our club layout and for the traveling modules.

Sounds like they a winner! Also sounds like my voltmeters and ammeters would no longer be required?

I don't bother with voltmeters, they're not telling me much as I know what voltage comes from the bricks.   Ammeters might be useful, just to know what load is on the various power districts.

Makes sense....Thanks.

I will second the PH-180s. Been using two of them for several years and I agree with GRJ's views on them. He was probably the one that gave me the idea to use them originally. Great source of power!

I have 2 isolated loops of track and use one TIU channel & PH-180 per loop. (DCS & Legacy only, no conventional.) No problems so far. I should add that I also have TVS diodes and PSX-ACs on each PH-180. As a friend of mine says, 'anything worth doing is worth over doing'.   (But, as I recall, he was talking about drinking beer and not layout power...)

Personally, I would keep all the volt/amp meters, but I like gadgets and dials and stuff.   As GRJ says the Amp meters are probably the useful ones with the PH-180s and not so much the volt meters. Unless you also like gadgets and dials that is...

I should have added above that I have crossovers between loops and trains go between tracks frequently with no problem using the separate PH-180s for each loop.

Hi RTR12....

Yep....I'm a fan of gadgets as well. I'm also a fan of control panels and lionel's tubular track. I like the sounds the rail car wheels make across the track joints.

But it's funny because as I run my trains I'm starting to realize that I should build control sub panels to control areas or sections of switches from different train table locations/layout perspectives. I guess that's from the freedom we have being able to use a remote to control the trains from anywhere around the table.

If I understand your layout description correctly, you have 2 loops of track that are connected by crossovers and the loops are isolated by insulation points at the crossovers correct? So as you cross from one loop to another you are crossing from one "power district" (loop) to another "power district" (loop). Have you ever accidentally parked a lighted rail car across an insulation point bridging 2 "power districts"? Did you encounter any problems if you did?

Junior

When asking a MTH DCS question ALWAYS wait for Barry BROSKOWITZ 's  reply before taking action.

He wrote the Book(s) on DCS.

Yes, crossing from one loop to the other also crosses between my two power sources/districts. Since they cross between loops I don't recall ever having parked any cars or trains between the two loops. Since I use PH-180 bricks to power each loop I would not expect problems if I ever did though? The voltage outputs of the two bricks are pretty close. Don't recall the exact voltages of each, but they were close enough I didn't think there would be any problems.

The sub panels might be a good idea for you. I use Atlas track and switches and started out to use an AIU to control them. In order to get things up and running I just installed the Atlas switch controllers near the switches, which I also wanted along with the AIU. After using the switch controllers where they are I decided I liked them that way and still have not added the AIU. I do still have plans to add the AIU though, for routing and things like that, maybe some accessories, lighting and other things as well.

I also have analog gauges on the power for both loops, similar to your setup. I got some digital volt meters for a voltage car that I copied from GRJ, and with a little if his assistance. When I got ready to add meters to the loop power I could no longer find any digital meters for the voltages or trains use. They seem to have just vanished...so I got the analog ones instead. I haven't looked lately, but they were still unavailable last time I looked for them.

gunrunnerjohn posted:

The PH180 has one of the best, if not the best circuit breaker of any of the brick transformers.  I swear by them, they are great!

They are great.

AlanRail posted:

Junior

When asking a MTH DCS question ALWAYS wait for Barry BROSKOWITZ 's  reply before taking action.

He wrote the Book(s) on DCS.

 

I don't question Barry's replies. I follow them. We are also blessed with many Techs that spend their valuable time helping out here. They add an invaluable asset to this forum. I weigh every response and take each into consideration before moving forward. I follow Barry for the DCS signal, many of the techs for any engine or board issues, and many of our electronics techs for the rest. This has helped me run when DCS (the system) seemed to be causing issues. Many times it was not to blame.

 With the free advice from so many talented people here, and the moderators for keeping us on track,  this forum continues to be the best.