Page 454 - IRSEM_Main Book

(d) Route Release

(i) Tests shall be carried out to ensure that once a signal is cleared for a
particular route, position of none of the points in the route can be
changed when track circuit immediately in advance of the signal is de-
energised.

(ii) Where sectional route release is provided, it shall be ensured that a
sub route does not release only by picking up of the concerned track
relay (s) but the same should be released only after the next track
circuit has also dropped and picked up except for the berthing portion
of track circuits.

(iii) Where sectional route release is not provided, tests shall be made to
ensure that the entire route remains locked when any of the track
circuits beyond the signal up to the track circuit controlling the last
point is de-energised.

(iv) In cases where the route is controlled by single track circuit, the route
shall be released after prescribed time delay to be effective after the
concerned track circuit has been occupied and cleared by the train.

(e) Time Release

Time release, where provided, shall be tested to ensure that it will be
possible to alter the route or set up a conflicting route or change the
position of the points in the route only after the signal is put back to 'ON'
and the prescribed time interval has lapsed. Similar tests shall be carried
out for overlap release, where time release is provided for releasing the
overlap after clearance of last track circuit in rear of berthing track and
occupation of the berthing track, if any. Also overlap shall get released only
after concerned signal knob/button is normalized wherever required.

(f) Signal Indication Circuits

Indication of 'ON' position of all signals shall be checked for its
correspondence with aspect displayed at site. Each signal shall then be
cleared after setting its route and the indication of each aspect shall be
checked for its correspondence with the aspect displayed at the site. This
test shall be carried out for each signal as well as for direction type route
indicator where provided. In the case of later, it shall also be ensured that
the indication relay is not energised and the indication does not appear
until the minimum number of lamps/LEDs as required are actually lit.

Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 402 of 535