Power Generation & Control

Power Zones on the SDR

Each end of the railway is a separate booster district, fed by its own DB150 booster. This provides up to 10A track power; with an N gauge loco taking perhaps 0.25A, it is definitely overkill. The accessory decoders are fed by the DCS100 booster output, ensuring they always have power.

Each booster district is split into separate power zones. The principle I've used here is to separate the main lines from the station & yard areas: derailments are much more likely in those, and they need to be separated. The main lines, on the other hand, are unlikely to suffer because the train movements are more simple: consequently these don't need to be broken up as much.

The South Downs Railway has four reverse loop zones. One reverse loop - with three parallel storage tracks - is located under Portsmouth station. The other, with a single track, is in front of Petersfield station. These tracks each need their own autoreverser. Each reverse loop  area - under Clanfield and by Petersfield - has its own PM42 channel for short circuit protection: I have used two because they are in separate booster districts.

 power_zones

Here is a list of the zones used on the railway:

Booster Board Channel Zone Track Area

Block

Dets

Detectors
DB150 1 PM42 31 1 A Portsmouth Approach & platforms 12 52 53 54 55 57 58 59 60 65 66 67 68
DB150 1 PM42 31 2 B Portsmouth Yard, Engine Shed & Eastleigh 9 50 51 56 61 62 63 64 69 70
DB150 1 PM42 31 3 C Green line at Portsmouth end 12 25 26 27 28 36 38 71 73 74 99 100 109
DB150 1 PM42 31 4 D Portsmouth Loop 3 reverse loop 2 33 102
DB150 1 PM42 32 1 E Portsmouth Loop 1 reverse loop 2 35 104
DB150 1 PM42 32 2 F Portsmouth Loop 2 reverse loop 2 34 103
DB150 1 PM42 32 3 G Orange line at Portsmouth end 14 23 24 29 30 31 32 37 39 72 75 76 101 105 110
DB150 1 PM42 32 4 H Reverse loops isolator 0  
DB150 2 PM42 33 1 J Reverse loop isolator 0  
DB150 2 PM42 33 2 K Clanfield 8 17 18 19 20 21 81 82 83
DB150 2 PM42 33 3 L Green line 16 12 14 15 22 42 43 44 45 49 77 80 94 95 96 106 107
DB150 2 PM42 33 4 M Orange line 12 13 16 40 41 46 47 48 79 97 98 108 111
DB150 2 PM42 34 1 N Petersfield Loop 2 11 88
DB150 2 PM42 34 2 P Fiddle yard green 12 2 3 4 5 84 85 86 87 117 118 119 120
DB150 2 PM42 34 3 R Fiddle yard orange 12 6 7 8 9 90 91 92 93 113 114 115 116
DB150 2 PM42 34 4 S Fiddle yard sidings 4 1 10 89 112