Power district

[dave75]

Looking at expanding my dcc plank layout, have read lots about power districts but have yet to find a decent simple definition of what one is. 

Leaving aside the hardware required which seems to be a circuit breaker etc and thinking just of the track, is a power district any different from a DC "section" 

Ie a lengths of track electrically isolated from ajoining pieces by isolated rail joins or cuts in the rail?

 

[WIMorrison]

It is an area that is, or can be, powered separately from the rest of the layout. It will be separated by a switch, (electronic or manual) or it could be supplied power by a totally separate feed, e.g. a booster.

[dave75]

Sorry poorly worded question. 

 

On the trackside , are power districts separated from each other by an insulated rail joiners on each rail ?

[WIMorrison]

Yes

[dasatcopthorne]

Power districts are mostly used to Stop a short in one area from stopping trains in another. For example, on a terminus to fiddeyard layot there might be locos with lights on or diesels ticking over or steam locos making appropriate sounds in the terminus and someone causes a short in the fiddle yard. The fiddle yard are will cut out but the terminus stuff will continue to 'run'.

So double track gaps and each area fed through a District Cutout. The cutouts are fed from the same bus. 

If you're not worried about a short shutting down the whole layot then don't bother with them.

Edited April 26 by dasatcopthorne

[WIMorrison]

6 minutes ago, dasatcopthorne said:

Power districts are mostly used to Stop a short in one area from stopping trains in another.

 

Power districts can be, and often are, areas provided with power from a different source that the command station e.g. a booster. They can also be used to bring power up sequentially when there are large capacitive loads. To say that they are mostly used in the scenario you describe is incorrect and misleading.

 

 

[dasatcopthorne]

6 hours ago, WIMorrison said:

 

Power districts can be, and often are, areas provided with power from a different source that the command station e.g. a booster. They can also be used to bring power up sequentially when there are large capacitive loads. To say that they are mostly used in the scenario you describe is incorrect and misleading.

 

 

 

You may consider my description incorrect but it certainly isn't misleading in the slightest.

 

But thanks for your very kind comments.

 

Dave.

[Izzy]

14 hours ago, dave75 said:

Looking at expanding my dcc plank layout, have read lots about power districts but have yet to find a decent simple definition of what one is. 

Leaving aside the hardware required which seems to be a circuit breaker etc and thinking just of the track, is a power district any different from a DC "section" 

Ie a lengths of track electrically isolated from ajoining pieces by isolated rail joins or cuts in the rail?

 

 

Yes, it's exactly the same in principle. Splitting a layout into separate power districts can be done for a variety of different reasons and there are several ways of doing it depending on what is required. The simplest is just to feed each section through an on/off switch as you would a DC powered layout, doing so to aid with fault finding or short circuit issues. Or power each through a CB so that if a short occurs in one section the rest of the layout remains okay. Another is for power draw where boosters power each section.  Much thus depends on what the layout owner wants, with the size of the layout and the number of locos running on it playing a large part in deciding what is best.

 

Personally I feel that for a lot of DCC users with smaller layouts and one operator just the one section is all that is needed because if a short occurs then the attention is taken with dealing with that. A continuous circuit layout however is another matter and where such arrangements as power districts etc. then becomes helpful. A separate bus for the track and accesories is probably best though whatever else is chosen.

 

Bob

[Ron Ron Ron]

9 hours ago, dave75 said:

Sorry poorly worded question. 

 

On the trackside , are power districts separated from each other by an insulated rail joiners on each rail ?

 

Each rail needs insulation from the adjacent rail in the next district, but all rails are powered and it doesn't matter if a loco bridges the gap, provided all power districts are in phase with each other.

 

The first use of Power Districts, was to provide adequate power to different parts of  large layouts, using separate Boosters to power each district.

In fact, the original (unofficial) definition of as "Power District", was a section of the layout, fed by it's own Booster.

With the increased use of Circuit Breakers, that definition has been watered down to also include sections protected by CB's. Those were previously described as "Sub-Districts"; i.e. sub-divisions within a single Power District.

 

 

7 hours ago, WIMorrison said:

 

Power districts can be, and often are, areas provided with power from a different source that the command station e.g. a booster. ......

 

 

Pedant hat on.

Sorry Iain, I can't help it !!!   🙄

 

A Command Station doesn't provide track power.

It's the built-in Booster that does that.

For example, the Roco Z21 box, or the Lenz LZV200 etc, etc,  contain both a Command Station and a Booster (Power Station in original Lenz and NMRA terms).

 

I'll take a lie down now.........

 

 

.

[dave75]

 "but all rails are powered and it doesn't matter if a loco bridges the gap, provided all power districts are in phase with each other."

 

Thanks I think this was the information I was trying to discover, I did want to blow chips up by getting it wrong.

 

Which begs the follow up question how would power districts not be in phase? 

[meil]

On 26/04/2024 at 07:51, WIMorrison said:

It is an area that is, or can be, powered separately from the rest of the layout. It will be separated by a switch, (electronic or manual) or it could be supplied power by a totally separate feed, e.g. a booster.

Yes - and the easiest "Power District" is a baseboard. In other words each separate baseboard is treated as a power district with its own circuit breaker/district cut-out. That way a short on a baseboard will not affect the other boards.

[Ron Ron Ron]

51 minutes ago, dave75 said:

 Which begs the follow up question how would power districts not be in phase? 

 

They would not be in phase if each individual rail in the adjacent Power District (or sub-district), on the other side of the insulated rail joiner, has been wired in the reverse.

i.e. not the same feed wire (left -right, inner-outer, red-black or whatever colour)

 

The track power is actually a DCC signal, which reverses rapidly in phase.

So each Power District must be in sync with each other, because otherwise, a loco bridging the gap where the two sections of rail are out of phase would cause a short.

 

As an analogy, think of  + &  -  with  DC.

It would be the equivalent of a loco's wheels bridging  + &  -  as it crosses the gap between each isolated section of rail.

 

Adding additional Boosters will be OK (if connected properly) because they should work in sync....provide the actual wiring to each rail is the right way round.

Take the same care with connecting up Circuit Breakers.

 

 

.

 

 

.

[dave75]

Ah okay so by in phase essentially we mean the same polarity . Just as passing a loco across a section between 2  DC controllers, if they are "reversed" the loco does the little backwards/forwards dance.

 

Thanks very helpful 

[Phil Bullock]

It’s already been mentioned but it’s worth emphasis …. Having accessories on a seperate bus with its own circuit breaker will mean you can continue to change points if you get a track power short . 
 

Avoids the issue of not being able to change the point you have just tried to run through against the set route thereby creating the short 

Edited April 27 by Phil Bullock

[Ron Ron Ron]

35 minutes ago, dave75 said:

Ah okay so by in phase essentially we mean the same polarity....

 

Yes, but the polarity switches back and forth at a very fast rate.

The phase is keeping that switching in sync at the same timing.

[dave75]

Yes it acts like or is AC, but I think I can draw from this helpful discussion that I can build a DCC power district in the same way as I would a DC section. I just need to think about wire thickness and what hardware I need on the end of that wiring next.

[Izzy]

I, and many others from comments I’ve read, started off down the DCC road by using our then current DC layout, swapping out the DC controller for the DCC one, and leaving all the section switches on. I still wire the track in the same way now but have eliminated the switches.
 

Bob

[DCB]

1 hour ago, Izzy said:

I, and many others from comments I’ve read, started off down the DCC road by using our then current DC layout, swapping out the DC controller for the DCC one, and leaving all the section switches on. I still wire the track in the same way now but have eliminated the switches.

Bob

Why eliminate the switches.   It makes more sense to leave the switches so on start up you can add extra locos and lighted coaches to the load by stages   Switches with 1 amp breakers in series would allow a straight forward  change from DC to DCC.   My DC layout has Power  Districts, I now realise nearly 40 years after wiring it.    Up Up Main, Down Main, Up sdgs, Down Sdgs, Loco depot, Branch, Hidden sidings,  all switchable between several controllers and operating positions and all subdivided by  isolated sections.       As the layout is  24 ft long X 8ft plus a 30 foot branch fault finding would be impossible  without the power district switches.   With DCC my Horny Q1 would have shut the whole layout down when it dd its party trick of shorting out randomly,  As it is the switches isolate the fault to easily identify  which area of the layout  the fault has occurred at.     Mine also has isolating points,   With DCC non isolating points a derailment  short anywhere  on the layout, sidings  hidden in loco sheds etc, loco running into wrongly set point etc  could stop the layout completely , or stop it powering up.  Separating point power from  traction power is  essential.  for reliable operation.     People falsely claim DCC has less wiring

 than DC.    That was only true with low power relying on fish plates two wires to the track, point motors, signals etc plugged in .   But fishplates can't conduct much more than 2 amps and point blades 1 amp so people needed droppers and  As soon as "Droppers" and ""Buses" are used the reverse is the case.  adding huge numbers of soldered joints for a smaller number of DC Feeds.    Many 1970s layout plans had 3 (Three) feeds for the entire  8 X 4 

[Michael Hodgson]

23 minutes ago, DCB said:

Why eliminate the switches.   It makes more sense to leave the switches so on start up you can add extra locos and lighted coaches to the load by stages   Switches with 1 amp breakers in series would allow a straight forward  change from DC to DCC.   My DC layout has Power  Districts, I now realise nearly 40 years after wiring it.    Up Up Main, Down Main, Up sdgs, Down Sdgs, Loco depot, Branch, Hidden sidings,  all switchable between several controllers and operating positions and all subdivided by  isolated sections.       As the layout is  24 ft long X 8ft plus a 30 foot branch fault finding would be impossible  without the power district switches.  

I would not remove isolating switches from an existing DC layout being connverted to DCC, but that's not to say you need to install isolating switches on a new DCC layout.  A district cutout is just as good a way of isolating the affected section when you have a short. 

 

A derailed loco, a screwdriver or beer can standing across the running ralls may be easy enough to find, but smaller things like a track pin bridging an isolation break in the rails is a lot harder to find on a large layout.

[Phil Bullock]

18 minutes ago, Michael Hodgson said:

I would not remove isolating switches from an existing DC layout being connverted to DCC, but that's not to say you need to install isolating switches on a new DCC layout.  A district cutout is just as good a way of isolating the affected section when you have a short. 

 

A derailed loco, a screwdriver or beer can standing across the running ralls may be easy enough to find, but smaller things like a track pin bridging an isolation break in the rails is a lot harder to find on a large layout.

or a metal watch strap …. But with 18v 7amps you soon know about that one! 

[5BarVT]

4 hours ago, Phil Bullock said:

or a metal watch strap …. But with 18v 7amps you soon know about that one! 

That sounds like a “been there, done that, got the T-shirt” comment. 
Paul. 

[meil]

22 hours ago, dave75 said:

Which begs the follow up question how would power districts not be in phase? 

That issue raises its head with a Free-mo get-together. They have a polarity tester which is used to ensure across-baseboard polarity.

 

See: https://forum.mrhmag.com/post/dcc-polarity-tester-12196234

Edited April 28 by meil

[Izzy]

On 27/04/2024 at 14:24, DCB said:

Why eliminate the switches.   It makes more sense to leave the switches so on start up you can add extra locos and lighted coaches to the load by stages   Switches with 1 amp breakers in series would allow a straight forward  change from DC to DCC.   My DC layout has Power  Districts, I now realise nearly 40 years after wiring it.    Up Up Main, Down Main, Up sdgs, Down Sdgs, Loco depot, Branch, Hidden sidings,  all switchable between several controllers and operating positions and all subdivided by  isolated sections.       As the layout is  24 ft long X 8ft plus a 30 foot branch fault finding would be impossible  without the power district switches.   With DCC my Horny Q1 would have shut the whole layout down when it dd its party trick of shorting out randomly,  As it is the switches isolate the fault to easily identify  which area of the layout  the fault has occurred at.     Mine also has isolating points,   With DCC non isolating points a derailment  short anywhere  on the layout, sidings  hidden in loco sheds etc, loco running into wrongly set point etc  could stop the layout completely , or stop it powering up.  Separating point power from  traction power is  essential.  for reliable operation.     People falsely claim DCC has less wiring

 than DC.    That was only true with low power relying on fish plates two wires to the track, point motors, signals etc plugged in .   But fishplates can't conduct much more than 2 amps and point blades 1 amp so people needed droppers and  As soon as "Droppers" and ""Buses" are used the reverse is the case.  adding huge numbers of soldered joints for a smaller number of DC Feeds.    Many 1970s layout plans had 3 (Three) feeds for the entire  8 X 4 

 

For your particular layout what you have chosen to do is certainly best for you and I can see the advantages it provides. Really, in a general sense, wiring a layout is or should be no different whether it's for DC or DCC with the size of a layout and how it is intended to be operated the overriding factor as to how that is arranged. The 'only two wires' thing is/was just a headline to get people interested as to the the differences DCC could provide. I only have small layouts where the elimination of section switches saves valuable space. Indeed it enables me to have small handheld plug-in switch units for signals and points etc. which would just be too large if section switches were also needed, both in respect of the overall size and the mass of extra wiring involved. Like so much else in regard to model railways, and indeed life in general, it's those horses for courses scenario.

 

Bob

Edited April 28 by Izzy

[Michael Hodgson]

3 hours ago, Izzy said:

 

The 'only two wires' thing is/was just a headline to get people interested as to the the differences DCC could provide.

 

 

It was an excellent sales pitch aimed primarily at the many modellers who say "I dont understand electrics".

[WIMorrison]

IIRC it was actually the advertising for Hornby Zero One that used the 'only two wires' statement 😁