Page 532 - IRSEM_Main Book

(a) Length of parallelism between the cable conductors and the electrified track.

(b) Soil conductivity.

(c) Screening efficiency of the cable sheath where existing.

(d) Return current through the rails and return conductor where provided.

(e) Mutual inductance between catenary and the cable conductors.

(f) Separation between catenary and cable.

(g) Current carried by the catenary etc.

Section 2: Signal Structures in RE Area

22.2.1 Colour light signals only shall be used in electrified areas.

22.2.2 On electrified sections, the masts, insulators, wires and supports obstruct the
visibility of Signals. In addition, the Signals have to be so erected that they
maintain a minimum clearance from the live parts of the O.H.E. The
instructions in this section shall be strictly followed in so far as the electrical
clearance is concerned. These instructions may be taken as a rough guide in
determining the location of signals, which would afford the best visibility to the
Loco Pilots of approaching trains. However, the actual visibility shall in all
cases, be checked by a Signal Sighting Committee and action to improve the
visibility taken on the recommendations of the Committee.

22.2.3 The location of signals and the protection required shall be worked out from
the following signal clearance diagram for Broad gauge.

Drg. No 22-D1 For Tangent tracks & tracks with super elevation less than 60 mm.

Drg. No 22-D2 For Curved tracks with super elevation 60 mm to 140 mm.

Drg. No 22-D3 For Curved tracks with super elevation 140 mm to 185 mm.

22.2.4 In these diagrams the un-shaded portion shown above the standard moving
dimensions is the area into which a signal posts or any of its fittings shall,
under no circumstances, be allowed to infringe. The shaded envelope around
this is the area into which a signal or its fittings shall not normally be allowed to
infringe. If due to unavoidable reasons, a portion of the signal post or its fittings
has to infringe into this shaded area, special protective measures as detailed
in para 22.2.6 shall be taken. The dotted outline in Drg. Nos. 22-D1, 22-D2,
22-D3 for Broad Gauge is applicable when there are two sets of Catenary and
Contact wires parallel to each other in the same span, viz. insulated and un-
insulated overlap locations. It is to be noted that these diagrams are not
applicable to (i) anchor spans, (ii) turnouts, (iii) 3 meters on either side of
masts, and (iv) in loco sheds and inspection pits. The diagrams are also not
applicable when there is a feeder line running along with masts or where
booster transformers and return conductors are provided.

Chapter 22: Requirements Of Signalling in 25 KV AC Electrified Area Page 475 of 535