(10-07-2017, 02:15 PM)yuriy Wrote: Hello,
Could anyone give me some links on the most complete books and guides on calculating railway track circuits in Britain.
I'm trying to generalize the calculation methods that are used in Russia, with those used in other countries. I decided to start with Britain. Among the material that I could find, including the present site, I have realized that the general approach is very different. In Russia, there are five mandatory modes of operation of the rail circuits: normal, shunt, control, short circuit and continuous cab signalling mode. Each of the modes is calculated in a certain way.
Waiting for response
In the UK mainline, track circuits are not used to provide continuous cab signalling, although the Irish Republic (Eire) does use what they call CAWS on some of their lines around Dublin. The early automated London Underground lines such as the Victoria line did utilise speed codes, but this system has since been replaced. The High Speed line (Channel Tunnel Rail link) uses the French TVM430 that does provide speed codes via the track circuits, but that whole line is rather more an extension of French practice to reach London rather than what is generally thought of as British!
For day to day railway application, no one does TC calculations for project work or maintenance work. Obviously the designer of the track circuit feed and relay equipment must do so, but the vast majority of signal engineers just take their product and install and test it according to the product information. The IRSE exam does include TC calculations so that people are aware of broad general principles to get an intuitive understanding of their operation including associated hazards and faults.
You'll see in the calculations that:
the condition of maximum energisation with no train and perfect insulations is considered,
the condition of varying "ballast resistance" is considered,
the condition of the train shunting the track is considered (the "drop shunt" needed to cause the track relay to de-energise having previously been fully energised),
the condition of the removal of the train shunt is considered ("pick up shunt" that permits the track relay to energise having previously been fully de energised.
I guess that these must relate in some way to the modes of operation that you have listed; perhaps you could explain a little more about what each of the names mean......
PJW