stds of interlocking
TRANSCRIPT
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Standards of Interlocking
As per old manual (of 1955)
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Standards of Interlocking
Old SEM (para 170 for 2 aspect & para 174
for multiple aspect) lays down the
following Standards of Signalling andinterlocking:
Standard I Permits speeds upto 50 kmph
Standard II Permits speeds upto 75 kmphStandard III Permits unrestricted speed
for run through trains
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Standard I
SEM para 171 lays down the requirements for Std I
for 2 aspect Signalling. (a) Isolation: Not compulsory.
(b) Signals : Outer and Bracketted Home
Starter is optional
Warner only on MG, if trains run through.
All signals to be operated from a Lever frame under
SMs control. (c) Points : As per para 142
(d) Interlocking: (i) Between facing points and signals by key locks
shall be so arranged that a signal cannot be taken off
unless the facing points are correctly set and locked.
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Standard I (contd.)
(d) Interlocking (cotd.) :
(ii) If warner is provided, interlocking between warner and points
must extend to trailing points.(iii) If points keys are electrically transmitted, insulation standard
shall be same as for Block wires.
(iv) Interlocking between points and signals must ensure that no
signal can be taken off for a line fitted with trap points unless the
trap point has been closed.
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Standard II
SEM para 172 lays down the requirements of
interlocking for Std II for 2 aspect signalling.
(a) Isolation : Main line must be isolated. (b) Signals : Outer, Warner and bracketted Home
Starters are optional
Where Starter is not provided, warner shall prove
receipt of Line Clear on the BI
(c) Points : As per para 143
(d) Interlocking : (i) Interlocking between points and signals may
be direct or indirect. All signals must be operated
from a lever frame controlled by SM.
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Standard II
(d) Interlocking (contd.) :
(ii) Interlocking between points and signals same as for std I and
must ensure correct setting of all trailing points for movement
over them.(iii) If points and signals are operated from either end of station,
interlocking between them must be direct.
(iv) SM should have control over Home and LSS.
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Standard III
SEM para 173 lays down the requirements of
interlocking for Std III for 2 aspect signalling.
(a) Isolation : Main line must be isolated. (b) Signals : Outer, Warner, Bracketted Home and Starter. Adv
str as necessary.
(c) Points : As per para 144
(d) Interlocking : Between points and signals must be direct and
comply with requirements in section A - J. Note 1: A passenger warning board at 1 km and Goods warning board
at 1.4 km in rear of Outer should be provided if warner is not
separated.
Note 2: Unrestricted speed over indirectly interlocked siding points
may be permitted if point equipment is as per para 144
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Standards of Interlocking
for multiple aspect signalling Para 174 (ii) lays down the requirements of
isolation,
Para 174 (iii) lays down the requirements of
signals, and
Para 174 (iv) lays down the requirements of
points equipment and interlocking
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Standards of Interlocking
for multiple aspect signalling Isolation requirements : No difference
Equipment of Points : No difference
Interlocking requirements : No difference
Signals :
Std I : Distant and Home
Std II : Distant, Home and Starter
Std III : Distant, Home and Starter
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Equipment of Points
Para 141: For speeds upto 15 kmph over
facing points
Para 142: For speeds upto 50 kmph over
facing points
Para 143: For speeds upto 75 kmph over
facing points
Para 144: For speeds in excess of 75 kmph
over facing points
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Equipment of Points
Para 141:
(i) A bolt and cotter individually fitted to each
switch rail and padlock or a clamp and apadlock for locking the switch rail to the stock
rail.
(ii) A gauge tie plate where steel sleepers are
not provided.
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Equipment of Points
Para 142: (i) A key lock of approved type.
(ii) A means for locking each switch independently.
(iii) A means for preventing the points from being unlocked during
the passage of the train, unless the arrangement is such that a key
is used to release the signals and cannot be brought back to the
points until such signals have been put to the on position.
(iv) A means for detecting each switch independently by therelative signals.
(v) A gauge tie plate where steel sleepers are not provided.
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Equipment of Points
Para 143 :
(i) A plunger type facing point lock. If the
plunger is hand operated or is of the economicallock type, its full travel should be detected by
the relative signals.
(ii) to (v) : Same as for Para 142 (ii) - (v) (ii) A means for locking each switch independently.
(iii) A means for preventing the points from being unlocked during the passage of the train,
unless the arrangement is such that a key is used to release the signals and cannot be brought
back to the points until such signals have been put to the on position.
(iv) A means for detecting each switch independently by the relative signals.
(v) A gauge tie plate where steel sleepers are not provided.
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Equipment of Points
Para 144 : (i) A plunger type facing point lock.
(ii) A means for detecting the full travel of the lockplunger by relative signals when the lock and switches
are operated by the same lever.(It is desirable that
plunger detection is also provided for independently
operated FPLs. (iii) A means for preventing the points from being
unlocked during the passage of train.
(iv) to (vi) : Same as Para 142 (ii), (iv) & (v)
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Comparison1. Isolation
Item Std I Std II Std IIINI
Main line
isolation
Isolation ofpassenger lines
from goods
lines & sidings
Not required Required
R E Q U I R E D
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Comparison2. Signals
Item Std I Std II Std IIINI
Two aspect:
A classN o t u s u a l l y a d o p t e d Warner, Home,
Starters
Two aspect:
B class
Outer &
Commonhome
Outer &
Bracketted
home
Warner in
MG, if reqd.
Outer &Brackettedhome. Warner
shouldinterlock withB.I., if strs notprovided
Outer,
Bracketted
home,
Warner &
startersTwo aspect:
C class N o t u s u a l l y a d o p t e dWarner,
Home
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Comparison2. Signals
Item Std I Std II Std IIINI
Multi aspect:
B class
Distant, home Distant, home Distant, home,
Starter
Distant, home,
Starter
Multi aspect:
C class
Distant &homeN o t u s u a l l y a d o p t e d
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Comparison
3. Points
Item Std I Std II Std IIINI
Locking Bolt & cotter Key lock of
approved type
Plunger type FPL,
which may be
hand operated
Plunger type
FPL operated
from LF
Operation From a lever framewhere points &
signals are grouped
L o c a l l y o p e r a t e d
Switch
Detection
Not required A means for detecting each switch independently
should be provided
Lock Detection N o t r e q u ir e
d
Reqd if Hand
operatedDesirable
Route Holding NAKey used to release signals cannot be
brought back till signal is replaced to ON
Lockbar
or TC
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Comparison
Item Std I Std II Std IIINI
Interlocking Not
required
4. Interlocking
Indirect by
key locks.
Warner
should
interlock
trailing
points.
Direct
locking bet
signals
Indirect by
key locks
extends to
trailing
points.
Direct
locking bet
signals
Direct
interlocking
bet signals
and points.
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Important points:
The major difference between Std I and Std II is that of
isolation.
Std I and Std II are generally used on low density routes
(mostly single line sections).
In Std I, the points are individually operated by spring loaded
levers whereas in Std II, they are grouped and operated from
a small ground frame.
In Std I, Home need not be interlocked with trailing points
whereas Std II requires this interlocking.
Std III does not permit indirect locking between points and
signals.
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