Page 497 - IRSEM_Main Book

(c) It must not be possible to release the crank handle/point NX key unless
the signals have been put back to 'ON' position and concerned route is
released. However, if the route remains locked due to what so ever
reason, it shall be possible to release the crank handle/point NX key after
a time delay of 120 seconds from the time the signals have been put
back to 'ON' position. Each such CH/NX keys release operation shall be
recorded on non-resettable counter.

(d) In major yard where number of points are more, these points should be
grouped in different zones maintaining the yard flexibility. The crank
handle/point NX key for each group of point machines should be so
arranged that they cannot be interchanged.

(e) Siding control key for manual operation of siding points, taking off from
running lines, shall be so interlocked that it may not be possible to clear
the signal leading over to that line when the key is released for operating
siding points for shunting purposes.

(f) It must not be possible to release the crank handle/point NX key unless
the signals have been put back to 'ON' position and concerned route is
released. However, in case of failure of Interlocking or for any other
emergency case (E.I/both Control Terminal & Control Panel/both Control
Terminals fails) an ‘Extreme Emergency Key’ and self restoring ‘Extreme
Emergency Button’ shall be provided. Turning of key along with pressing
of ‘Extreme Emergency Button’, shall restore all signals to ‘ON’ aspect
and after a time delay as per Table-1, all CH/NX Keys shall be free and it
shall be possible to release the CH/NX key. To normalize this emergency
operation, ASM shall restore back the ‘Extreme Emergency Key’. Each
such ‘Extreme Emergency key’ release operation shall be recorded on a
non-resettable counter.

21.1.14 Cross Protection features

(a) For purely internal circuits including vital circuits, double cutting or cross
protection may not be provided, unless specifically required.

(b) All external circuits shall be suitably protected from cross connections and
rendered immune to false operation by induced voltages in RE areas.

21.1.15 Control Panel/Control Terminal [Video Display Unit (VDU)]

(a) Stipulations given in above paras shall apply also apply to Control Panel
for Electronic Interlocking Installations. These Control Panels shall not
be used in future E.I installations.

(b) Control Terminal/multiple Control Terminals shall be of appropriate size to
display layout of the Yard in well-proportioned dimensions and shall display
all functions clearly distinguishable. Normally Control Terminal/multiple
Control Terminals shall be provided in redundant mode.

(c) Video Display indications on Control Terminal shall conform to Control
Panel indications and UFSBI Block panel as Block working built into
Electronic Interlocking(EI) as covered in Section above or other
approved type.

Chapter 21: Relay & Electronic Interlocking Page 443 of 535