k kinda a silly questions (dcc blocks)

[ramoutandabout]

why do we need them ?

[simon1966]

You don't have to have them, but they can be useful.

There are 2 main reasons to my way of thinking.
1. Short protection
2. Power distibution

If a DCC command station detects a short condition it will shut down the track power to the layout. So if the layout is large with several operators then the entire layout would shut down if one of the operators had a derailment and caused a short. By dividing the layout into blocks, each protected with its own short protection, only the block with the short would be shut down. This would allow other operators in other blocks to continue running while the short is removed in the shut down block.

On larger layouts that have to potential to run many locomotives, there may simply not be enough power in the DCC booster to allow everything to run. Then it is helpful to add a booster and to devide the layout into independent power districts. All still controlled by the same command station but with independent power. This allows many more locos to run at once. It would not be unusual for these separate power districts to then be sub divided into blocks for short protection.

On a smaller layout it may not be needed. My layout is in a room about 14' x 20' There are only every 3 of us running at once. I have split it into 2 blocks, one for the main yard and one for the main line loop around the room. So either my yard shuts down or the main shuts down. This works well enough for me.

[RichS1]

Well said Troy

[ramoutandabout]

thanks guyes!!!

[simon1966]

QUOTE: Originally posted by RichS1

Well said Troy

It's Simon from Troy [:D]

[Adelie]

The other reason is for block detection capability. I've got my layout (40' x 14', essentially a big folded dogbone) divided into four power districts (staging, main yard, inside track and outside track). Each of those double-gapped blocks is then divided into single-gap detection sections of predetermined lengths (a tad longer than trainlength). This allows me to wire them through block occupancy detectors that will later be used for signals and ultimately also computer control.

The reason for splitting the inside and outside tracks of the mainline is that I can set up one of the boosters as an auto-reversing booster. Since the inside and outside tracks are normally opposite direction, any train crossing over to use the opposite track as a passing track would cause a short in the process. By putting them on different boosters and setting one to auto-reverse, that short is detected and the avoided before it causes a problem. If the layout had fewer of these crossovers and the mainline was shorter, I would have probably just set up a few auto-revering modules, but in this case it made sense to just isolate the two sides of the double-track mainline on completely different boosters.

In my humble opinion, it is a good idea to set up double-gapped power districts on any decent-sized layout and use single-gapped detection sections on just about any layout. Even if you wind up just wiring them all to the same bus and don't use separate boosters, auto-reversers or block occupancy detectors, for the price of a few insulated joiners you wind up preserving the option for later on.

Those reasons are in addition to what Simon discussed.

[tomikawaTT]

Quick answer - troubleshooting!

If electrical blocks can be isolated easily (screw terminals on standard terminal boards) it becomes possible to narrow down the location of a 'phantom' short in rapid order. Even where a DCC layout uses multiple short protectors, each one usually protects a substantial amount of track and a number of track feeders. By being able to separately disconnect each feeder, the short will magically disappear when the feeder to that length of track is disconnected. It's much easier to check a few meters of track for a short than it is to try to debug your entire division point yard as a unit.

That said, just how did that piece of tinsel get into the Haruyama tunnel???

[Pennsy58]

Its the return of the elussive Gremlins. Those little buggers put tinsel in my tunnel too............. &*@#!!