Page 387 - IRSEM_Main Book

17.2.6 Track Indicators: At Track circuited stations where track indicators are
provided, the following arrangements shall be made:

(a) At Panel Interlocked/Route Relay Interlocked Stations

(i) Normally, the track indicators would show no light when the line is
unoccupied. When action is initiated to set the route for taking off a
signal and the concerned route is set, the track indicator light for the
route shows Yellow/White, if unoccupied. However, if any portion of the
track circuited area is occupied, a "RED" indication is shown on the
panel diagram, irrespective of the route being set or not.

(ii) The track indicators would show white/yellow light when the track is
cleared after the intended movement is completed till the route signal
button or switch is restored to normal unless the panel interlocking/route
relay interlocking is provided with Automatic Route Release facility in
which case the indication would be lit until the sub route/sectional route/
route is released.

(iii) In case of berthing track having multiple track circuit sections, it is
desirable to show individual indications of each track circuit on the panel.

(b) At Other Stations: The indicator shall show yellow/white Light when the
line is unoccupied and RED when line is occupied.

17.2.7 Limiting resistance of DC track circuits shall be adjustable and of an approved
type.

17.2.8 Track Relays

(a) DC track relays of approved design shall be used. In future installations,
only plug in type track relays (9 ohm) shall be used, both in Non-RE & RE
areas.

(b) Q series track relay must be used in conjunction with Q series slow to pick
up relay as a repeater relay.

(c) Excitation of DC Track Relay: The relay shall be excited at minimum 125%
of its rated pick up voltage under minimum ballast resistance condition and
normal working voltage of the supply. The maximum excitation shall not
exceed 235% for QBAT Relays and 300% for other plug- in type relays.

17.2.9 Maximum Length of Track Circuits: Maximum length of track circuit under
different track parameter conditions shall not exceed the limits as given in the
following table. Maximum length of track circuit under different track parameter
conditions shall not exceed the limits as given in the table below.

Chapter 17: Train Detection Track Circuits & Axle Counters Page 335 of 535