Block Detection Track Wiring


doylep@...
 

Hi
I am currently planning a new layout with a large, off-scene, double ended staging yard.
I am using DCC Concepts Cobalt Alpha products - switch machines, control panel switches etc.  My layout will have an accessory bus separate from the track power bus.  The control panel will use the Alpha Switch product to give turnout control and LED indication of routes on a mimic panel.
I am planning on having block detection in the yard, using current sensing block detection devices, connected to the new DCC Concepts ESP wireless transmission devices which will signal back to my mimic control panel where LEDs will indicate whether a track is occupied or not.
To the nub of my question:  Given the yard tracks will be 3 to 4 metres in length (10 in total apart from the central mainline in the middle), and therefore each track will have up to 4 sets of track feeders (based on the usual recommendation of feeders to every length of rail), how can I best place the current sensing devices?  Do I need to create a "parallel" track bus for each track, using one block detector on one of these bus wires, and then connect the specific track feeders to that bus specific to that track?  Or can, I just have one track bus, and place a block detection device on one feeder to each of the tracks?
Any help will be appreciated.
Thanks


Don Weigt
 

doylep,

You need to use that sub bus wiring you described.

If you had several feeders to the block, and only one had a detector, some or all of the track wouldn't have functional occupancy detection, as much or most of the current would pass through those wires, not through the detector. There is some uncertainty, because it depends on the quality of the connections made by the rail joiners, and rail resistance, and how the occupancy detectors sense the current.

The right way is the hard way, as is often the case...

Don Weigt


--
Don Weigt
Connecticut


whmvd
 

Hi Doylep,

The first option is the right one. The second one reates parallel paths next to the current sensor, which means you're never going to know which part of the total current is going to go through the detector. The detector really needs *all* current to go through it to be reliable.

There is one alternative way, though, and that is to make each yard track its own bus simply by bridging each joiner with a parallel wire connection. That's what I'd choose, but if you prefer multiple drops to one sub-bus that itself connects to the main bus through the detector for that section - that's fine, too.

Wouter


On Thu, 28 Oct 2021 at 10:22, <doylep@...> wrote:
Hi
I am currently planning a new layout with a large, off-scene, double ended staging yard.
I am using DCC Concepts Cobalt Alpha products - switch machines, control panel switches etc.  My layout will have an accessory bus separate from the track power bus.  The control panel will use the Alpha Switch product to give turnout control and LED indication of routes on a mimic panel.
I am planning on having block detection in the yard, using current sensing block detection devices, connected to the new DCC Concepts ESP wireless transmission devices which will signal back to my mimic control panel where LEDs will indicate whether a track is occupied or not.
To the nub of my question:  Given the yard tracks will be 3 to 4 metres in length (10 in total apart from the central mainline in the middle), and therefore each track will have up to 4 sets of track feeders (based on the usual recommendation of feeders to every length of rail), how can I best place the current sensing devices?  Do I need to create a "parallel" track bus for each track, using one block detector on one of these bus wires, and then connect the specific track feeders to that bus specific to that track?  Or can, I just have one track bus, and place a block detection device on one feeder to each of the tracks?
Any help will be appreciated.
Thanks


Don Vollrath
 

Using your words… create a "parallel" track bus for each track, using one block detector on one of these bus wires, and then connect the specific track feeders to that bus specific to that track. 
 Also do that for the group of turnouts as they fan out to the storage tracks so you can provide an occupancy indicator for trains within the fan out area. 

DonV