Page 498 - IRSEM_Main Book

(d) Operation of Signals, Points and other Controls such as Gate, Crank
handle, Siding, Slot, Block Working etc. shall be carried out through
appropriate dropdown menus or other approved means.

(e) Control Terminal shall have suitable protection facility against
unauthorized operation which may be provided by physical ‘SM Key’ in a
separate box and key contacts are taken to pick up two separate ‘SM Key’
relays in relay room for redundancy purpose. These relay contacts are
taken as input through two different input cards preferable in different
OC’s and ‘SM Key IN’ bit shall be made by their parallel proving inside E.I.

(f) All Emergency operations shall be two-step process protected against
unintended operations.

(g) Control Terminal shall have provision for Signal, Point and Line Block
Collars equivalent of Control Panel in the form of individual ‘Block’ & ‘Un-
Block’ feature which shall remain effective even during change over from
one Control Terminal to other Control Terminal. ‘All Un Block’ option
shall be provided while E.I starts up to un-block all signals, points & lines
after a time delay of at least 120 seconds. SM’s key shall be required for
unblocking of a function whereas no SM’s key required for blocking.
There should not be any automatic unblocking of functions. Blocking of a
function shall be indicated on Control Terminal by different mark or
colour over the concerned function.

(h) Where Control Panel and Control Terminal are provided, it shall be
possible to switchover the controls from Control Panel to Control
Terminal and vice-versa, and where two Control Terminals are provided,
it shall be possible to switch the controls from one Control Terminal to
other Control Terminal through suitable means by either manual switch
or password.

(i) Indication that E.I system is healthy shall be displayed on the Control
Panel using a blinking green LED or blinking green indicator on Control
Terminal.

(j) Operation of points shall be possible only, when the interlocking is free
and relevant point track circuit is clear. Emergency operations provided
when point zone track circuit fails and after line verification from site by
traffic personnel, it shall be possible to operate the concerned point by
inserting an emergency key in a separate box provided interlocking is
free. Each such operation shall be recorded on a non-resettable counter.

(k) Each ‘Normal’ or ‘Reverse’ operation of point shall be controlled through two
output relays derived from two output bits should be from different output
cards of E.I.

(l) Last controlled position of points shall be available by using latch relay in
point control circuits.

(m) Mid stroke point reversal preventing feature shall be provided to prevent
starting of operation when the point is under operation or tried for other
position during mid stroke.

Chapter 21: Relay & Electronic Interlocking Page 444 of 535