(19-01-2017, 02:33 PM)Abhishek.Vidyarthi2@amey.co.uk Wrote: while entering from non-electrified area to electrified area, we need to install double IBjs.Can anybody brief me on this?
what are the measures to be taken care, while entering to electrified area with axle counters, TSS on?
What measures to be taken care while entering to electrified area with S&C thereon?
Any more thing?
I have been through NR/SP/ELP/21085 SECTION 8.1.7 BUT WANT MORE CLEAR IDEA.
It is mainly to make sure that traction current is stopped from going into an area which has not been immunised for it. The rationale for two pairs is that if one fails, you have time to detect it and correct it before the other one fails - one alone is enough to stop the traction current, the second is for redundancy.
Now, you raise a very good question about axle counters because we have been having some interesting discussion on requirements for, responsibility for provision, asset ownership and maintenance requirements on areas of our railway at the moment. Block joints belong to the pway (they are part of the track). Position of them is generally determined by signalling, within constraints like not locating them too close to welds or other track features. Generally, in TC areas, signalling sorted out the provision of them and hence, where they are the norm, they are a convenient thing to block off the traction current normally at the point that the adjacent signalling needs to be protected from it. The scenario that we have is that a railway that is not yet electrified has been resignalled with axle counters. A siding area with minimal signalling (and that which is there is, in any case, traction immune ready like the rest of the railway) is present and naturally, there are no block joints anywhere. The issue is, as the electrification comes through, that the siding in question handles trains carrying flammable gases and needs protection from stray traction current in case of sparking being a cause of ignition. The signalling design did not require them and the electrification design assumed they would be there.
Aside from cross discipline co-ordination issues, I think the answer to your question comes down to the question of whether the railway beyond the electrified area needs protection from the possibility of traction current being present in the rails (and hence may leak into the ground and other systems connected to the rails).
As for your question about S&C, like all good fringes, you want to pick you area carefully so that things are simplified. The "end of the electrified" area is not necessarily the track immediately beyond the point at which electric trains run (where the wires are) is really means "the area that can cope with traction currents" so is in reality some distance from where the electric trains run. So where you have a (complex) junction where a non electrified line leaves the electrified area, put the blocking off joints away from the junction at a point where (eg if it is a TC area) there would be block joints anyway, or at some convenient place for installation and maintenance in the future.
