Page 418 - IRSEM_Main Book

Section 6: Installation of Double Line Block Instruments

18.6.1 (a) Quick acting relays shall not be used for stick circuits of the block
instrument. Two immunized plug-in type 'Q' series relays connected in
tandem or one 'Q' series slow to pick up AC immunized relay shall only be
used. The total pick up time of relays used shall not be less than 300 msec.
DC 3-position polarized line relay of approved type shall only be used in the
line circuit for block working.

(b) Block release shall be by the operation of two track circuits sequentially.

18.6.2 Tests to be Conducted at the Time of Installation

(a) Check that the commutator handle is locked first before the "Train On Line"
indication appears on the indicator when the handle is turned from "Line
Clear" to "Train On Line" position.

(b) Check that the Block Clearance Relay picks up only after the commutator is
turned to "Train On Line" position.

(c) Check that the Last Stop Signal can not be taken 'OFF' when the
commutator is in other than "Line Clear" position.

(d) Check that the Last Stop Signal is automatically replaced to 'ON' when the
train enters the block section and continues to remain in the 'ON' position
until the train has arrived at the receiving station and a fresh “Line Clear” is
obtained.

(e) Check that when the commutator is turned from "Line Closed" position to
"Train On Line" position, the commutator is free for return to “Line Closed”
position.

Section 7: Maintenance of Token Instruments - General

18.7.1 Register of Block Instruments

The Senior Section Engineer (Signal) shall maintain a register containing the
following information:

(a) The type of instrument, its serial number, location, and name of manufacturer.

(b) Date of installation.

(c) Date of last overhaul.

(d) Particulars of all tokens working in each block section and particulars of
tokens either removed or lost irrecoverably during the course of working
and of those introduced as replacement.

18.7.2 Census of Tokens: Each Sectional JE/SSE(Signal) shall take a census of the
tokens working in various block sections at least once in six months and shall
keep their record in the register of Block Instruments. He should also record
this information in the Signal History Book at every station and keep it up to
date in this respect.

Chapter 18: Block Instruments, BPAC & IBS Working Page 366 of 535