Stds of Interlocking

8/14/2019 Stds of Interlocking

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Standards of Interlocking

As per old manual (of 1955)


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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


3/21

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.


4/21

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.


5/21

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.


6/21

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.


7/21

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


8/21


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


9/21


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


10/21

Equipment of Points

Para 141: For speeds upto 15 kmph over

facing points


facing points


facing points

Para 144: For speeds in excess of 75 kmph

over facing points


11/21

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.


12/21

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.


13/21

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.


14/21

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)


15/21

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


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


17/21

Comparison2. Signals


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


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


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.


20/21

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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Documents

Stds of Interlocking