Page 413 - IRSEM_Main Book

(b) Double Line:

(i) Double Line Block Instrument (SGE)

(ii) Block working with Axle Counter

(iii) Block Proving by Axle Counter

(iv) Block working directly from EI

Note: If any other block instrument is to be used, prior approval of Railway Board shall
be obtained.

18.2.2 Media

(a) Block instruments may use special PVC insulated quads in the aluminum
sheathed cable 4 or 6 quad jelly filled telecommunication cable or other
suitable communication means, like OFC and radio, for their working.

(b) When quad cable is used for the working of block instruments, Block
Telephone and Block Bell circuits shall be worked through a transformer
utilizing the two pairs of block quad. The Block circuits shall be worked on
the phantom pair or by other suitable means.

(c) When OFC, Radio or other communication means are used for block
working, Universal Fail Safe Block Interface (UFSBI) of approved design
shall be used. UFSBI shall be installed in relay room and the connected
block panel shall be provided in ASM room. In case the distance between
UFSBI and block instrument is more than 500 meters, block filter and block
bell and telephone shall be inserted in cable pairs connecting them.

18.2.3 Others

(a) Protective Devices of approved type consisting of two chokes connected in
series with a four terminal condenser connected across the junction between
two chokes and earth shall be used. A surge arrestor of suitable type shall
also be provided across the condenser to absorb surges under faulty
conditions. The arrangement is illustrated in Drg. No. 18-D4.

(b) The Block Bell shall be worked through Block Bell equipment of approved
type.

(c) Separate line battery or DC-DC converter shall be used for each block
instrument. This battery shall feed only the block instruments and not any
other circuit.

Note: Two different earths shall be provided separately for SPD and Block. However,
the protective earth for SPDs of all Block equipments should be connected to common
ring earth of Indoor Signalling system.

Chapter 18: Block Instruments, BPAC & IBS Working Page 361 of 535