Page 510 - IRSEM_Main Book

(h) Relay to Relay wiring on the same rack should be as far as possible direct
without intermediaries like tag block/terminals.

(i) Identification Marker for identifying the terminals and tags shall be provided
to each terminal to identify the circuits for which it is used.

(j) Relay racks shall have sufficient capacity to take additional equipment to the
extent of 15% of equipment provided to permit additions and alterations.

(k) Charts showing the position of relays on relay racks and contact analysis
of relays indicating the spare and used contacts shall be prepared and
kept in the relay room.

(l) For future expansion, provision shall be made to accommodate additional
relays, relay groups & racks in the relay room.

21.3.2 Fuses, Terminals and Terminal Links

(a) Cartridge type fuses shall preferably be of Non deteriorating type. Where
screw cap cartridge type fuses are used, these shall be of different colour
codes for different current rating and these shall be non - interchangeable.

(b) Fuses shall be so grouped that blowing of a fuse has minimum
repercussion on train operation.

(c) The fuses when blown off, shall preferably give a visual indication.

(d) Each group of circuits shall be carefully protected by fuses in the cabins
and in location to facilitate easy fault localization.

(e) Fuses shall be so arranged that they can be easily replaced without
causing interference or unsafe conditions to other circuits.

(f) Cartridge fuse links shall be approved type.
(g) The terminal block and tag blocks shall be of approved type unless
otherwise specially permitted.

(h) The terminal boards provided at the locations and other places shall be
provided with suitable links to facilitate isolation of the two sides of the
circuits which are connected through the terminal links.

(i) For vital circuit fuse auto change over system of approved type to be
provided.

21.3.3 Power Supply Arrangements
The power supply systems for Signalling Installations shall be as per details
given in Chapter 16 on "Power Supply Arrangement systems for Signalling
Installations".

21.3.4 General Arrangements

(a) Air conditioning may be provided for every signalling interlocking (PI/RRI)
installation with more than 100 routes. For E.I installations air conditioning
may be provided irrespective of number of routes to improve reliability.

Chapter 21: Relay & Electronic Interlocking Page 453 of 535