Page 485 - IRSEM_Main Book

The MSDAC information through ethernet interface (Main & Redundant) is connected
to the ethernet switch which transfers the same onto dark fiber. Two such switches are
used at each location one each for UP and DOWN direction firbers.

The Vital Relays (ACPRs) of each track section are picked up at the sending end of track
section (either in AG or station). The status of vital relays is read by the OCs, and
transmitted to Central Interlocking Unit for logic processing, and the status of aspects
is again sent to corresponding OCs for driving the Automatic Signals.

D. Reset features of MSDAC

The reset arrangement is proposed at three levels using Track Sections and
Supervisory Track Sections, two of which are automatic reset arrangements and
one is manual reset.

(i) L -I : Automatic reset with redundant track section:

Once the train has cleared both the track sections, and any one of the track sections
is in failure state, the track section, which is in clear condition will reset the one in
fail condition. The track section, which is under reset is kept in preparatory mode
and the clear track section information is used to clear the signal.

(ii) L-II : Automatic reset with Supervisory track section:
When a supervisory track section is clear, all the track sections falling completely
within the jurisdiction of that supervisory track section can be assumed to be clear.
If any track section fails and it’s corresponding supervisory track section is clear, it
will automatically reset the failed track section.

In case of automatic resetting with supervisory track section, the reset track
sections will be kept under preparatory mode, and the corresponding signal will
continue to be in ‘ON’ aspect, until a train with low speed enters and exits the
track section with equal count at the boundaries of track section.

(iii) L -III : Manual Reset with Line verification:

In case of failure of Level -1 and Level -2 reset, manual resetting has to be carried
out, which resets all the track sections in the section under consideration. One
reset box at train sending station along with its corresponding Line verification (LV)
box at other station is used to manually reset all the track sections between both
the stations of a particular direction of movement. This reset can be done only
when Station Masters of both the stations have ascertained that all the track
sections between the stations are clear of trains in that particular direction.This
will reset and set all the DPs in preparatory mode. The clearance of train in each
section with balancing of count will make the track section clear and bring to its
normal mode of working.

E. Power Supply Arrangement

Each AG is provided with a Mini IPS, for which the input supply of 230 V AC is from UP
AT and DN AT at each location. The necessary power supplies for EI OCs and MSDAC are
derived from the Mini IPS. MSDAC works on a voltage range of 19-72 V DC. Hence 24 V
DC supply with suitable current capacity from Mini IPS serves the purpose. In stations,
the necessary power supplies are derived from the Major IPS.

Chapter 20: Automatic Block Signalling Page 431 of 535