Page 385 - IRSEM_Main Book

(f) Relay End and Feed End of the track circuit should be located at the
boundaries of the track circuit.

(g) Loading of Track Relay Contacts: All the contacts of the track relay shall
be loaded as far as possible. Where spare contacts are available, they
shall be connected in parallel to the loaded contacts.

17.2.2 Jumper Connections

(a) Jumper connections shall normally be so made that the whole of track circuit
is in series excluding traction return rail. When the rails of a track circuit are
in parallel, care shall be taken that the jumper connections are effective.

(b) Jumper connections, preferably duplicated, shall be so arranged that they
are as far as possible protected from damage.

(c) All connections to the track shall be of sufficient length and allow for rail
creep. Connections shall be firmly fitted to the web of the rail.

(d) For short jumpers, galvanized iron wires and for long jumpers cables, may
be used. Where galvanized iron jumper is used, duplicate jumpers shall be
run. The cross section of galvanised iron wire shall not be less than 8 SWG.
Where cables are used, the size shall not be smaller than 7/0.750 mm.

(e) The lead wires used for connecting the feed set to the feed end boot leg/track
lead Junction Box (JB) and the track relay to the relay end boot leg/track
lead JB shall preferably be of copper conductor having a minimum cross
section of 2.5 sq.mm. Lead wires crossing the track should be protected
through suitable means.

(f) Track lead JB shall be clear of ballast.

(g) The Feed as well as Relay Ends +ve & -ve leads shall be connected by
using individual 2 x 2.5 sq.mm cable, duly paralleled at each end.

17.2.3 Bond Wires and Rope Wires

(a) Bond wires/Rope wires shall be of an approved type. Duplicate wires shall
be installed close to the fish plate, it is desirable to use bond wire clips for
securing the bond wire.

(b) Bond holes shall be drilled with a twist drill and the bonds driven-in
immediately. The wires may be fixed by using channel pins in the holes or
by brazing/welding.

(c) The resistance of rail and bonding per 1000 meters of track shall not
exceed 0.5 ohm for track circuits longer than 700 meters. A rail and bond
resistance up to 1.5 ohm per 1000 meters of track may be allowed for
length of track circuit less than 700 meters.

(d) The rail bonding and connections to the relay and feed set shall be made
according to approved drawings.

(e) The lugs of impedance bond connections shall be firmly fixed by pressing
rivets into the web of the rail with a bond press.

Chapter 17: Train Detection Track Circuits & Axle Counters Page 333 of 535