केवल कार्ाालर्ीन प्रर्ोग हे तु
For Official Use only
भारत सरकार - GOVERNMENT OF INDIA
रे ल मंत्रालय - MINISTRY OF RAILWAYS
Handbook
on
Safety in
Signalling
Ver-2.0
CAMTECH/S&T/202223/SS/2.0
August-2022
End User: SSE/JE & Signal Maintenance Staff
End User: SSE/JE & Signal Maintenance Staff
of Indian Railways
of Indian Railways
Maharajpur, Gwalior (M.P.) – 474005
Handbook on
Safety in Signalling 2.0
CAMTECH/S&T/2022-23/SS/2.0
August-2022
Prepared by: Shalini Bansal, SSE/Comp.
(Under the Guidance of Shri Navneet Kumar Varma, Dir/S&T/CAMTECH
and P.K. Wakankar, SSE/Signal/CAMTECH)
i
FOREWORD
In Indian Railways, signalling system is used to direct railway traffic and keep
trains clear of each other at all times thereby ensuring passenger safety as well
safety of assets. In addition to this, safety of manpower involved in installation
and maintenance of signalling assets is also important. With the modernization
of signalling infrastructure the focus is to prevent hazards by improving safety
and enhancing capacities. Some of these hazards result due to erroneous safety
procedures, malfunctioning of equipment or tools, lack of knowledge of safety
procedures or failure to utilize necessary safety equipment such as conductive
mat, goggles, protective apron etc. Hence it is necessary to ensure safety
measures at workplace, both for maintenance personnel as well as equipment.
With the advent of new technologies, sophisticated and sensitive electronics and
computer based signalling equipments are being used in Indian Railways. Apart
from general safety precautions, these systems require additional safety
precautions as per RDSO guidelines and manufacturer's specifications.
CAMTECH has reviewed the "Handbook on Safety in signalling" prepared in
the year 2006 and updated it with latest safety precautions in the light of latest
developments in the field of railway signalling.
I hope that the information given in this handbook will be quite helpful to the
personnel engaged in maintaining the Signalling system in Indian Railways and
taking preventive measures to avoid safety hazards.
CAMTECH, Gwalior
Date: August 2022
JITENDRA SINGH
Principal Executive Director
ii
Blank Page
iii
PREFACE
Signalling System enhances safety in train operations which is inherent in the form of
interlocking between various functions. However, additional safety precautions are
required for the safety of equipment and manpower. Upgradation and replacement of
equipment in use over Indian Railways is a continuous process and is undertaken
based on its condition, operational needs and availability of resources. Hence safety
guidelines are required to be revised after any new development. Over the years, there
have been revolutionary improvements in the field of railway signalling due to
advancement in technology, for example, Integrated Power Supply, Digital Axle
Counter, LED Signal, Electronic Interlocking, use of Optic fibre cable etc. Their
installation and maintenance procedures are also different from conventional
signalling systems. These systems require distinct safety precautions such as earthing
and surge protection, electrostatic discharge precautions etc.
In view of the above, a need was felt to review the safety guidelines for signalling
issued by CAMTECH in the year 2006. Apart from general safety precautions, this
handbook also covers various safety precautions for Mechanical & Electrical
Signalling installations, Modern Signalling installations based on Electronics &
Communications, Fire Safety in Signalling installations and Additional Safety
Precautions for Signalling in RE Area.
We are sincerely thankful to Railway Board, Signal Directorate RDSO Lucknow,
West Central Railway, Northern Railway and all S&T personnel of Indian Railways
who helped us in preparation of this handbook.
Since technological upgradation and learning is a continuous process, you may feel
the need for some addition/modification in this handbook. If so, please give your
comments on email address dirsntcamtech@gmail.com or write to us at Indian
Railways Centre for Advanced Maintenance Technology, In front of Hotel Adityaz,
Airport Road, Maharajpur, Gwalior (M.P.) 474005.
CAMTECH, Gwalior
Date: August 2022
NAVNEET KUMAR VARMA
Director (S&T)
iv
v
TABLE OF CONTENTS
FOREWORD .............................................................................................................................. i
PREFACE ................................................................................................................................ iii
TABLE OF CONTENTS ........................................................................................................... v
ISSUE OF CORRECTION SLIPS ............................................................................................ x
DISCLAIMER .........................................................................................................................xii
OUR OBJECTIVE .................................................................................................................. xiv
CAMTECH PUBLICATIONS ............................................................................................... xvi
ABBREVIATIONS ............................................................................................................. xviii
Section 1..................................................................................................................................... 1
GENERAL ................................................................................................................................. 1
1.1
Introduction: ................................................................................................................... 2
1.2
How to achieve the safety: ............................................................................................. 2
1.2.1 General Safety Precautions to be observed while working on signalling circuits: ........ 2
1.2.2 First Aid in case of Electric Shock:................................................................................ 2
1.3
General Safety Precautions during working with Electrical & Electronic Equipment: . 3
1.4
General Safety Monsoon Precautions for S&T Equipments: ........................................ 4
Section 2..................................................................................................................................... 8
Safety in Mechanical & Electrical Signalling installations ....................................................... 8
2.1
Electric Lifting Barriers: ................................................................................................ 9
2.1.1 Safety Measures to be Provided at Level Crossings: ..................................................... 9
2.1.2 Safety Precautions During Maintenance: ....................................................................... 9
2.2
Electric Point Machine: .................................................................................................. 9
2.2.1 Precautions-General: ...................................................................................................... 9
2.2.2 Disconnection of point: .................................................................................................. 9
2.2.3 Locking: ....................................................................................................................... 10
2.2.4 Notches in Stretcher Blades: ........................................................................................ 10
2.2.5
Obstruction Test: .......................................................................................................... 10
2.2.6 Obstruction Test for Point Machine for Thick Web Switches: .................................... 10
2.3
Track Circuits: .............................................................................................................. 10
2.3.1 Maintenance of DC Track Circuits: ............................................................................. 10
2.3.2 Maintenance of Audio Frequency Track Circuits (AFTC) in RE Area: ...................... 11
2.4
Relays: .......................................................................................................................... 12
2.4.1 Requirements: .............................................................................................................. 12
2.4.2 Installation: ................................................................................................................... 13
2.4.3 Sealing of Plug-in Relays:............................................................................................ 14
vi
2.4.4 Maintenance: ................................................................................................................ 14
2.4.5 Periodical Inspection: ................................................................................................... 14
2.4.6 Replacement: ................................................................................................................ 15
2.5
Relay Room: ................................................................................................................ 15
2.5.1 Precautions: .................................................................................................................. 15
2.6
Control Cum Indication Panel (CCIP)/Control Panel: ................................................. 16
2.6.1 Safety Requirements: ................................................................................................... 16
2.6.2 Do’s & Don’ts for Control Cum Indication Panel (CCIP)/Control Panel in PI/RRI: .. 17
2.7
LED Signals: ................................................................................................................ 19
2.7.1 Safety Precautions: ....................................................................................................... 19
2.8
Block Instruments: ....................................................................................................... 20
2.8.1 Safety Precautions: ....................................................................................................... 20
2.8.2
Prevention of Irregular Operations: ............................................................................. 20
2.8.3
Locking and Sealing Facilities: .................................................................................... 20
2.8.4
Prevention of Unauthorized Operation: ....................................................................... 21
2.8.5
Overhauling of Block Instruments: .............................................................................. 21
2.9
Fuses: ........................................................................................................................... 21
2.9.1 Precautions: .................................................................................................................. 21
2.10
Earth Leakage Detectors (ELD): .................................................................................. 22
2.10.1 Precautions: .................................................................................................................. 22
2.11
Integrated Power Supply System: ................................................................................ 22
2.11.1 Safety Precautions Before Commissioning of IPS: ..................................................... 22
2.11.2 Safety Precautions During Maintenance: ..................................................................... 22
2.11.3 General precautions:..................................................................................................... 23
2.12
Low Maintenance Lead Acid (LMLA) battery: ........................................................... 23
2.12.1 Safety Precautions: ....................................................................................................... 23
2.13
Precautions for Valve Regulated Lead Acid (VRLA) Battery: ................................... 25
2.13.1 Safety Precautions: ....................................................................................................... 25
2.14
Signalling Cables: ........................................................................................................ 26
2.14.1 Safety Precautions: ....................................................................................................... 26
2.15
Earthing, Lightning & Surge Protection Devices: ....................................................... 29
2.15.1 Earthing: ....................................................................................................................... 29
2.15.2 Lightning & Surge Protection Devices (SPD): ............................................................ 30
Section-3 .................................................................................................................................. 34
Safety in Modern Signalling installations based on Electronics & Communications ............. 34
3.1
Data Logger:................................................................................................................. 35
3.1.1 Do’s and Don’ts: .......................................................................................................... 35
vii
3.2
Axle Counter: ............................................................................................................... 35
3.2.1 Axle Counter Resetting - Block Section/Intermediate Block Signalling/ Automatic
Signalling: .................................................................................................................... 35
3.2.2 Axle Counter Resetting - Station Section: ................................................................... 36
3.2.3 Do’s and Don’ts: .......................................................................................................... 37
3.3
Universal Fail Safe Block Interface (UFSBI): ............................................................. 38
3.3.1 Do’s and Don’ts: .......................................................................................................... 38
3.4
Electronic Interlocking: ................................................................................................ 38
3.4.1 Safety Precautions: ....................................................................................................... 38
3.4.2 Electrostatic Discharge Precautions: ............................................................................ 38
3.4.3 Do’s and Don’ts: .......................................................................................................... 40
3.4.4 Do’s & Don’ts for dual VDUs: .................................................................................... 41
Section-4 .................................................................................................................................. 42
Fire Safety in Signalling .......................................................................................................... 42
4.1
Introduction: ................................................................................................................. 43
4.1.1 Recommendations/Suggestions for System Improvement by enquiry committee of
BPL division W.C. Rly: ............................................................................................... 43
4.1.2 Precautions to Prevent Fire Incidences at S&T installations: ...................................... 44
4.2
Precautions/Recommendations for RRI installations: ................................................. 45
4.2.1 First Aid Box:............................................................................................................... 45
4.2.2 Provisions in RRI Building Before Commissioning: ................................................... 45
4.2.3 Wiring and Cabling: ..................................................................................................... 45
4.2.4 Fire Extinguishers: ....................................................................................................... 46
4.2.5 Smoke Detectors: ......................................................................................................... 47
4.2.6 Fire Alarm System: ...................................................................................................... 47
4.2.6 Counselling: ................................................................................................................. 47
4.2.7 Circuit alteration: ......................................................................................................... 47
4.2.8 Joint inspection with Electrical department: ................................................................ 47
4.2.9 Storage of material: ...................................................................................................... 47
4.3
Do’s and Don’ts: .......................................................................................................... 47
4.3.1 Do’s: ............................................................................................................................. 47
4.3.2 Don’ts: .......................................................................................................................... 48
Section-5 .................................................................................................................................. 49
Additional Safety Precautions for Signalling in RE Area ....................................................... 49
5.1
Laying of Signalling Cables in RE Area: ..................................................................... 50
5.2
Electrical & Signal Clearance: ..................................................................................... 50
5.2.1 Clearances for Safety: .................................................................................................. 51
viii
5.3
DC Track Circuits in RE Area: .................................................................................... 51
5.3.1 Modification to track circuits: ...................................................................................... 52
5.3.2 Feed End: ..................................................................................................................... 52
5.3.3 Relay End: .................................................................................................................... 52
5.3.4 RE Bonding: ................................................................................................................. 53
5.4
Block Signalling in RE Area: ....................................................................................... 53
5.4.1 Type of Block Instruments Permitted in 25 KV RE: ................................................... 53
5.4.2 Special Arrangements for Block Circuits in 25KV RE: .............................................. 54
5.5
Feeding of Power to Signals in RE Area: .................................................................... 55
5.5.1 Direct feeding of signals: ............................................................................................. 55
5.6
Electric Operation of Point in RE Area: ...................................................................... 56
5.7
Relays to be used in RE: .............................................................................................. 56
5.8
Insulation of Rod & Wires: .......................................................................................... 56
5.9
Laying of Signalling Cables: ........................................................................................ 57
5.10
Earthing Arrangements in RE Area: ............................................................................ 57
5.11
Outdoor Signalling Circuits in RE Area: ..................................................................... 58
5.11.1 Maximum Length of Parallelism: ................................................................................ 58
5.12
Protection for Staff in 25 KV RE Area: ....................................................................... 58
5.12.1 Safety Precaution against proximity of a Live Conductor: .......................................... 58
5.12.2 Safety Precautions against Presence of Return Current in Rail: .................................. 59
5.12.3 Safety Precautions against induction in Metallic Bodies Situated Close to OHE: ...... 59
5.12.4 Safety Precautions for working on S&T Cables: ......................................................... 59
5.12.5 Safety Precautions for working on Electrical Circuits: ................................................ 59
5.12.6 Safety Precautions for Breakage of Catenary/Contact Wire: ....................................... 60
5.12.7 2.2 KV Charging as an Anti-Theft Measure: ............................................................... 60
5.12.8 Checklist of works to be completed: ............................................................................ 60
5.12.9 Maintenance in Electrified Areas: ................................................................................ 60
Section-6 .................................................................................................................................. 61
Safety & Integrity Checks for Interlocking/Logic Circuits ..................................................... 61
6.1
Interlocking Testing: .................................................................................................... 62
6.1.1 Factory Acceptance Test (FAT): .................................................................................. 62
6.1.2 Site Acceptance Test (SAT): ........................................................................................ 63
6.2
Periodicity of Tests (for Existing Installations – Relay Interlocking/ Electronic
Interlocking): ................................................................................................................ 65
6.3
Interlocking / Logic Circuit Tests for EI: ..................................................................... 65
REFERENCES ........................................................................................................................ 77
ix
x
ISSUE OF CORRECTION SLIPS
The correction slips to be issued in future for this report will be numbered as follows:
CAMTECH/S&T/2022-23/SS/2.0# XX date .......
Where “XX” is the serial number of the concerned correction slip (starting from 01
onwards).
CORRECTION SLIPS ISSUED
S. No. of
Correction
Slip
Date of issue
Page no. and Item
No. modified
Remarks
xi
xii
DISCLAIMER
It is clarified that the information given in this Handbook does not supersede
any existing provisions laid down in the Signal Engineering Manual, Railway
Board and RDSO publications. This document is not statuary and instructions
given are for the purpose of guidance only. If at any point contradiction is
observed, then SEM, & Railway Board/RDSO guidelines may be referred or
prevalent Zonal Railways instructions may be followed.
xiii
xiv
OUR OBJECTIVE
To upgrade Maintenance Technologies and Methodologies and achieve
improvement in Productivity and Performance of all Railway assets and
manpower which inter-alia would cover Reliability, Availability and Utilization.
If you have any suggestions & any specific comments, please write to us:
Contact Person
: Director (Signal & Telecommunication)
Postal Address
: Centre for Advanced Maintenance Technology,
Maharajpur, Gwalior (M.P.)
Pin Code – 474 005
Phone
: 0751-2470185
Fax
: 0751-2470841
E-mail
: dirsntcamtech@gmail.com
xv
xvi
CAMTECH PUBLICATIONS
CAMTECH is continuing its efforts in the documentation and up-gradation of information on
maintenance practices of Signalling & Telecom assets. Over the years a large number of
publications on Signalling & Telecom subjects have been prepared in the form of handbooks,
pocket books, pamphlets and video films. These publications have been uploaded on the
internet.
For downloading these publications
Visit www.rdso.indianrailways.gov.in
Go to Directorates → CAMTECH Gwalior → Other Important links → Publications for
download - S&T Engineering
or click on link
https://rdso.indianrailways.gov.in/view_section.jsp?lang=0&id=0,2,17,6313,6321,6326
A limited number of publications in hard copy are also available in CAMTECH library which
can be got issued by deputing staff with official letter from controllong officer. The letter
should be addressed to Director (S&T), CAMTECH, Gwalior.
For any further information regarding publications please contact:
Director (S&T) – 0751-2470185 (O)(BSNL)
Or
Email at dirsntcamtech@gmail.com
Or
FAX to 0751-2470841 (BSNL)
Or
Write at
Director (S&T)
Indian Railways Centre for Advanced Maintenance Technology,
In front of Hotel Adityaz, Airport Road, Maharajpur,
Gwalior (M.P.) 474005
xvii
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xviii
ABBREVIATIONS
Following abbreviations are used in this Handbook:
Abbreviations
Description
AC
Alternate Current
AFTC
Audio Frequency Track Circuit
ACI
Air Core Inductor
BPAC
Block Proving by Axle Counter
CCIP
Control Cum Indication Panel
CCITT
Consultative Committee for International Telegraphy & Telephony
CCTV
Closed-Circuit Television
CH
Crank Handle
CMU
Central Monitoring Unit
CRC
Cyclic Redundancy Check
DAC
Digital Axle Counter
DC
Direct Current
DG
Diesel Generating
DR
Green Aspect Controlling Relay
DWC-HDPE
Double Wall Corrugated- High Density Polyethylene
EI
Electronic Interlocking
EKT
Electric Key Transmitter
ELD
Earth Leakage Detectors
ETU
End Termination Unit
EUYN
Emergency Route Section Release Button
EWN
Emergency Point Button
FAT
Factory Acceptance Test
FP
Feeding Post
FSBI
Failsafe Block Interface
HHR
Double Yellow Aspect Controlling Relay
HR
Yellow Aspect Controlling Relay
HT
High Tension
IB
Intermediate Block
IPS
Integrated Power Supply
JPO
Joint Procedure Order
xix
LC/LX
Level Crossing
LED
Light Emitting Diode
LMLA
Low Maintenance Lead Acid
LT
Low Tension
LV
Line verification
OFC
Optical Fibre Cable
OHE
Over Head Equipment
PCB
Printed Circuit Board
PI
Panel Interlocking
POH
Periodic Overhauling
PVC
Polyvinyl chloride
RE
Railway Electrification
RRI
Route Relay Interlocking
RMS
Root Mean Square
SAT
Site Acceptance Test
SIP
Signal Interlocking Plan
SP
Sectioning and paralleling Post
SPD
Surge Protection Device
SSP
Sub-sectioning and Paralleling post
STLT
Selection Table/Locking Table
TC
Track Circuit
TSS
Train Stop System
TSR
Train Signal Register
TU
Tuning Unit
UFSBI
Universal Fail Safe Block Interface
VCOR
Vital Cut Off Relay
VDU
Visual Display Unit
VHF
Very High Frequency
VRLA
Valve Regulated Lead Acid
xx
Handbook on Safety in Signalling 2.0
Section 1
GENERAL
1
Handbook on Safety in Signalling 2.0
1.1
Introduction:
Unsafe conditions at a workplace or site are hazards that have the potential to cause injury
or loss of human lives. In the context of Railway operation, it may put the lives of
maintenance personnel as well as passengers in danger and at the same time may incur
damage to railway property and disrupt train traffic resulting in huge revenue loss. Some
of these hazards include erroneous safety procedures, malfunctioning equipment or tools,
or failure to utilize necessary safety equipment such as goggles and masks. Unsafe
conditions can be found in a variety of workplaces, for example Relay Room, Power
equipment room, Level Crossing Gate, Station yard, Signal post, near point machine etc.
in relation to S&T department. Hence it is necessary to ensure safety measures at
workplace, both for maintenance personnel as well as equipment.
1.2
How to achieve the safety:




By obeying the safety rules.
By using the safety equipment and precaution.
By using the safe methods while working and avoiding short cut.
By doing proper & time bound inspection/joint inspection & maintenance of the
equipment.
 By ensuring availability of the safety equipment in your possession.
 By ensuring availability of firefighting equipment/First aid box in equipment room.
 By ensuring Training/Counselling of staff.
1.2.1
General Safety Precautions to be observed while working on signalling
circuits:









1.2.2
Never use short cut operation while working with battery and other equipment.
While connecting measuring equipment ensure that it is connected with proper setting
as per specified guidelines.
Always use the instrument on higher range of the value if not known.
Before energization, check all the connections are proper as per circuit diagram and
fully tightened.
Before disconnection of the circuit ensure that information is to be issued to the
users/party.
Maintain properly and ensure that all the measuring instruments are in working
condition.
Good & qualitative maintenance is the key of reliability.
Your efficiency is judged by your quality of maintenance. Quality of maintenance is
worth for department.
Never use short cut.
First Aid in case of Electric Shock:

Switch OFF the power supply. If this is not possible then
protect your-self with dry insulating material and pull the
victim clear of the conductor. Do not touch the Victim with
your bare hands until he is clear of the conductor, but do not
waste time.
2
Handbook on Safety in Signalling 2.0

Place the victim in the Supine* Position.
* Supine position refers to a horizontal position with the face and upper
body facing up.





Fig 1: Supine Position
Keep the air passages clear by turning the head to one side,
opening the patients mouth and clearing it of water, saline mucus or blood, a lot of
which might have accumulated in the back of the throat.
If the jaw is rigid try to force the mouth open by pressure on the gum behind the last
molar tooth of the lower jaw. When the upper air passages are thus cleared, tilt the
head backward and force the jaw forwards from the angles of the jaw in front of the
ears. This would prevent mechanical obstructions to the upper air passages.
Then hold the chin up and forward with one hand and pinch the nostrils of the victim
with the other.
Take a very deep breath and apply your mouth to that of the victim and blow into his
mouth, until the chest of the victim moves up indicating filling of the lungs (Never
allow the chin to sag).
When the chest has moved up, withdraw your mouth and allow the chest to sink back.
REPEAT this process every three to four seconds until the victim begins to breathe
again or until he is taken over by a medical attendant. This method can be continued
in an ambulance during transit of the patient from the site of accident to the nearest
medical centre.
Fig 2: Artificial Respiration after electric shock



1.3
Have someone else to send for a doctor.
Keep patient warms and loosen his clothing.
Do not give liquids until the patient becomes conscious.
General Safety Precautions during working with Electrical &
Electronic Equipment:
The maintenance and troubleshooting of electrical and electronic equipment is done by
signal engineer/technician. During the above procedure the engineer/technician should
take the safety precautions to safeguard himself against electric
shock.
The following precautions are to be taken during maintenance,
and troubleshooting of Electric/Electronic equipment:

Do not touch the electric/electronic equipment unless you are
sure that there is no leakage current in the body of the equipment.
3
Handbook on Safety in Signalling 2.0

While working on the electrical/electronic equipment always use rubber shoes, mat,
gloves or dry wooden platform to maintain the separation from the earth.
Fig 3: Safety Shoes, Insulated Electric Gloves & Electrical Mat






1.4
Before switching on the equipment always ensure that the circuit is properly
connected and no person is working on the circuit.
Before doing any experiment always have full knowledge of experiment and all
required tools; equipment and circuits with you.
Never use short cut methods while rectifying a failure.
Before starting any maintenance, repair, always disconnect equipment from mains.
Never pull the plug from the socket by holding the lead wire of mains.
Whenever working on the mains your hands should be dry. Never touch the mains,
electrical equipment with wet hands.
If there is any high voltage capacitor in the circuit always touch or disconnect the
capacitor after discharging it.
General Safety Monsoon Precautions for S&T Equipments:



Ensure provision and cleaning of drainage system in yards to avoid water
accumulation in points and track circuited area.
Ensure provision of 100% insulated GFN liners and rubber pads in track circuited
area with PSC sleepers.
Ensure removal of vegetation, mud and muck from track circuited portion of the track
as well as on either side of tracks and in vicinity.
Fig 4: Vegetation, mud and muck at track
4
Handbook on Safety in Signalling 2.0

Ensure that All nylon pieces of insulated joints, Insulation of stretcher bars & point
rodding are intact and replace those in bad condition.
Fig 5: Stretcher bars & Point rodding




Ensure that defective/worn out glued joints are replaced before onset of monsoon.
In flood prone areas ensure that Track lead Junction Boxes are raised without
infringing Schedule of Dimensions.
Adjust the track circuit parameters within safe working limits.
Check all traction bonds in track Circuited Portion of track and attending deficiencies
through Electrical Traction department.
Fig 6: Traction bonds

Check and ensure proper Earthing for axle counter field equipments and Evaluator.
Fig 7: Earthing for Axle counter


Check & ensure all connections like rods, transverse bonds and feeds of adjacent track
circuits etc. do not touch the bottom of the rail. Ensure timely replacement of old
rusty track circuit bond wires.
Ensure lifting of point machines wherever required at identified water logged area.
5
Handbook on Safety in Signalling 2.0




Top up Gear oil in gear box and seal the top cover in point machine. Perform greasing
of point machines and cleaning of crank handle contacts. Ensure availability of
Gasket and Carbon in point machine.
Waterproofing of point motors shall be done for the points situated in low lying flood
prone areas. Spare point motors and contact assemblies shall be kept at stations.
Check cable entries to ensure that the cable is in healthy condition physically besides
meggering and ELD monitoring. Clean all the terminals to avoid deposition of
moisture on the accumulated dust, to avoid low insulation.
All point motors carbon brush covers shall be sealed with silicon sealant after proper
cleaning of commutators.
Fig 8: Point motors sealed with silicon sealant

Ensure availability of proper gasket in Signal units to prevent seepage of
moisture/water. All signal units should be completely sealed including any holes to
prevent moisture ingress.
Fig 9: Gasket in Signal unit

A plastic cover/canopy wherever required shall be provided on the back of the Signal
units, in case, leakage/seepage persists. Signal unit earthing also checked and must be
intact and <4Ω.
Fig 10: Plastic cover/canopy in Signal unit
6
Handbook on Safety in Signalling 2.0

Damaged/corroded portions of the location boxes should be repaired/replaced. Any
space between the base of the location box and its foundation such space, if existing,
should be filled up by mortar.
Fig 11: Location box

Identify cabins/relay and equipment rooms prone to rain water leakage/seepage and
take corrective steps.
Fig 12: Leakage/Seepage in rooms


spares must be kept at
Proper
tested
Station/IB/Gates. Mostly Electronic equipments may be defected due to lighting in
Monsoon like as S.P.T., Block bell equipment, Axle counter cards, LEDs of Signals,
different rating fuses etc.
Protective works provided for the cables at places like track crossings, culverts,
bridges, etc. shall be inspected prior to onset of monsoon and special attention has to
paid to these protective works soon after the first shower.
Fig 13: Cables at bridges/culverts
7
Handbook on Safety in Signalling 2.0
Section 2
Safety in Mechanical & Electrical Signalling installations
8
Handbook on Safety in Signalling 2.0
2.1
2.1.1
Electric Lifting Barriers:
Safety Measures to be Provided at Level Crossings:
{Ref: Annexure 14-A1 of New SEM (July-2021)}.

2.1.2
The safety measures to be provided at a Level Crossing Gate shall be as given in
Annexure A.
Safety Precautions During Maintenance:
{Ref: Para 14.3.2 of New SEM (July-2021)}









The time of operation of electric lifting barrier shall not exceed stipulated time.
Measured value of current should not exceed rated
values.
The satisfactory functioning of the lifting barrier by a
hand crank shall be checked.
All gate locking apparatus must be examined regularly
and working parts kept oiled.
Gate locks must be kept in good working order.
Proper working of audio/visual warning shall be ensured.
It shall be ensured that approach warning arrangement
Fig 14: Level Crossing Gate
where provided, is working satisfactorily and
(Electric Lifting Barrier)
effectiveness of Approach and Back locking provided
shall be ensured.
Communication of approved type, provided between Level Crossing gates and the
adjoining stations shall be checked in regard to their satisfactory functioning.
Heavy repairs, renewals or alterations to gate interlocking must not be carried out
until JE/SSE (Signal) concerned has arranged for the protection of the road traffic by
the concerned department and the work shall be carried out under proper
disconnection.
2.2
Electric Point Machine:
2.2.1
Precautions-General:




All switches shall be frequently tested to see if they are
in correct adjustment. For testing, the switches shall be
moved slowly and it shall be ensured that the switches
are set properly against the stock rail.
Do not operate the Machine locally without hand crank.
Do not short any electrical contacts manually under any
circumstances.
Do not disturb the pre-setting of the detection contacts
at site.
Fig 15: Electric Point Machine
2.2.2
Disconnection of point:
Always issue Disconnection Notice before performing any work in Point Machine except
for following:

Inspection and cleaning of inside equipment by opening the covers of Point Machines.
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Handbook on Safety in Signalling 2.0



2.2.3
Cleaning and/or Lubricating/Graphiting, without affecting any Physical/Electrical
connection.
Testing of Track locking.
Testing of point by obstruction test for lock only.
Locking:
{Ref.: Para 19.3.2 (b) of New SEM (July-2021)}
Electric Point Machine covers shall be locked. The cover provided for insertion of crank
handle shall also be locked with separate key providing access only for crank handle and
crank handle key.
2.2.4
Notches in Stretcher Blades:
{Ref.: Para 19.3.2 (c) of New SEM (July-2021)}
Notches/Notch profile of the locking, driving and detection slides should not be
tampered/reconditioned. Worn-out slides should be replaced with new ones.
2.2.5
Obstruction Test:
{Ref.: Para 19.3.6 of New SEM (July-2021)}

The point driving rod and the lock connections of the machine must be so adjusted
that with 5 mm thick test piece obstruction placed between the switch and the Stock
Rail at 150 mm from the toe of the Switch:
i. The point cannot be locked.
ii. The point detector contacts should not assume the position indicating point
closure.
iii. Friction clutch should slip.


2.2.6
The essential requirement for interlocking of point shall be periodically checked.
Each sectional JE/SSE (Signal) shall test the operating values of the machine and
adjustments of the machine by Obstruction test Every Month. The Sectional in charge
of the section shall carry out these tests Once in Three Months.
Obstruction Test for Point Machine for Thick Web Switches:
{Ref.: Para 19.4.6 of New SEM (July-2021)}
The detector slides, lock slides and drive rod must be so adjusted with 5 mm thick test
piece placed between the switch and gauge face of stock rail at 150 mm from the toe of
the point. The following to be observed:





2.3
Friction clutch de-clutches the motor from mechanism.
The point cannot get locked either by clamp lock or by locking segment inside the
point machine.
Lock segment does not enter into the notches of locking slides.
Switch detection contacts do not make.
The slipping current is not exceeding twice of the normal working current.
Track Circuits:
{Ref.: Section 3 Chapter 17 of New SEM (July-2021)}
2.3.1
Maintenance of DC Track Circuits:
Ensure the following:
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Handbook on Safety in Signalling 2.0




There is always a good connection between power feed and track, relay and track and
also between adjoining rails, through jumpers and rail bonds.
The ballast resistance always remains high and does not fall below prescribed
minimum values.
The limiting resistance shall be as high as possible.
The insulating joints are of high resistance.
Fig 16: DC Track Circuit Diagram



2.3.2
The surface of rail is clean and is free of dust, sand and foreign materials.
The circuit is properly energised during wet weather on minimum ballast resistance
conditions and during dry weather on maximum ballast resistance conditions. The
track circuit shall not be over-energised to such an extent that the shunting value
drops below 0.5 Ohms for all types of track circuits. These values shall be obtained
irrespective of whether the track is provided with concrete sleepers or wooden
sleepers.
The connection of DC track relay shall be quarterly interchanged to prevent
permanent magnetisation.
Maintenance of Audio Frequency Track Circuits (AFTC) in RE Area:
{Ref.: Section 4 Chapter 17 of New SEM (July-2021)}






Tuning area shall be devoid of check rails, level crossing, insulated bond and each
fish plated joint shall be bonded with jumpers of adequate thickness.
Special precautions shall be taken to ensure the tightness of connection of rail and
tuning unit.
A frequency assignment scheme for the track circuit shall be decided in advance and
it shall be strictly followed.
Terminal junction on insulation joint to track circuits with the same frequency is
prohibited. However, frequencies not belonging to same pair can be used.
Cable cores of same cable shall not be used for connecting transmitter & receiver of a
track circuit.
When wiring and installing track circuit, circuit pairing should be observed in the line
cables. Each transmission or reception shall use conductors from one same pair.
Circuit pairing results in cable transmission parameters being changed and may
induce significant cross talk levels in adjacent circuits.
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Handbook on Safety in Signalling 2.0


The design and installation of field equipment should take in account the requirements
for mechanised track maintenance and should not be hazard for men walking along
the track.
Protection against atmospheric voltage surges shall be installed on each pair of
conductors providing a link to the outside in order to limit the harmful effect of
lightening on electronic equipment. This protective arrangement shall cover against
both common mode and differential mode voltages on line.
Fig 17: Block Diagram of AFTC





2.4
Transmitter, receiver and power supply shall be mounted in standard relay rack in a
manner to allow maintenance and testing staff to view the track relay while making
adjustments.
TUs and ETUs shall be mounted at a minimum distance of two meters away from the
near rail as it gives good safety margin to staff.
In case of failure of track circuit, attempt shall not be made to pick up the track circuit
by adjusting the gain of receiver of TC without investigating the cause of drift in the
receiver voltage.
Impedance bond within track circuit shall be tuned with the correct resonating
capacitor across the auxiliary coil and this tuning shall match with the frequency of
track circuit.
Maximum length of track circuit depends upon various factors like ballast resistance,
frequency adopted, track layout (whether any level crossing or bridge falls within
track circuited area) and vendor of AFTC, and it cannot be laid down in absolute
terms. Broadly its length is limited to 700 m in end fed mode.
Relays:
{Ref.: Section 2 Chapter 21 of New SEM (July-2021)}
2.4.1
Requirements:


Approved type of Plug-in Line relays of Neutral/Polar Biased/Magnetic
latch/Interlocked type rated at 24/48/60 V DC shall normally be used. Approved type
of LED Lamp proving relays shall be used for LED Signal lamps.
Approved type of Relays shall be used in RE & Non-RE areas.
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Handbook on Safety in Signalling 2.0














2.4.2
Time element relays of approved type shall be used. Where approved electronic time
element relays are used, these shall be two in number and their contacts shall be in
series in the concerned time release circuits.
The relays, including track relays, located in the track side location boxes, shall be
plug-in type.
All plug-in relays and relay groups shall be provided with coding pin arrangement to
prevent the wrong relays/relay group being accidentally plugged-in during
replacement. All relays, relay groups shall be sealed.
As far as possible, all relays shall be housed in the Relay Room of the controlling
cabin to achieve maximum centralization.
Sequential proving of front and back contact shall be ensured where metal to metal
contact relays are provided.
Removal or replacement of plug-in relays/relay groups from the relay racks during
operation shall not cause any unsafe conditions in the circuits.
Where feasible all relays except track relays, shall have 10% of working contacts as
spare subject to a minimum of one front and one back to facilitate addition and
alteration to the circuits at a later date. Extra space (minimum 10%) to accommodate
repeater relays shall be provided in the relay rack to cater for future expansion.
Where magnetic latch relays are used, the circuit shall be so designed so as to prevent
undue dropping of the relay due to back EMF generated by other relays.
Wiring of 'Q' type relays shall be done through flexible multi strand wire preferably
and contacts to be paralleled as feasible.
Mercury wet contact type relay shall be used for flasher circuits, alternatively, a solid
state flasher may be used. If solid state flasher is used, flashing indication on
operating panel should be provided for indicating healthy condition of flasher.
Relays shall not be stored in the vicinity of damp or chemically polluted environment.
Sealing screws of the relays shall be intact.
Storage: Relays shall be kept in reasonable storage condition. It shall be ensured that
such a storage place is not in the vicinity of damp or chemically polluted
environment.
Transportation: Care shall be exercised in transporting the relays from the place of
storage to the work site so that the relays do not get damaged.
Installation:
As far as practicable, the Relay Room is not located in the vicinity of chemical factory,
loco shed or engine ash pits etc. In case it becomes unavoidable, necessary precautions
shall be taken so that relays are least affected by the chemical fumes, dust etc. and are
provided with dust free environment. Relay Room shall be provided with double locks
and door opening shall be monitored through Data Logger.




Where relays cannot be located in the Cabin, they shall be housed in location box of
approved type which are properly secured.
In 'Q' style relay the code pins configurations for plug in relay shall not be changed by
drilling additional holes on plug board to avoid fixing of a wrong relay which may
lead to unsafe condition. In Siemens K-50 relays, the Code pins position on base plate
should not be changed and to be retained as fixed by the manufacturer.
All relay clips shall be checked for proper locking in the base when plugged in.
Extreme care shall be exercised while removing the clips from the jacks of the plug-in
type relay.
In all installations, a relay index board shall be provided for locating relays easily.
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Handbook on Safety in Signalling 2.0




2.4.3
Relays involving external circuits shall have cross protection and double cutting.
Signal control relays shall preferably be provided with double cutting.
A contact analysis chart shall be prepared duly showing the contacts used circuit-wise
with reference and spare contacts available, wire count for each contact and relay
position in the rack.
Number of contacts in a circuit shall not exceed 45 Nos. due to voltage drop
consideration. The voltage across R1 & R2 of a relay shall not be less than 22 V.
Where available, spare contacts shall be paralleled with working contacts.
Sealing of Plug-in Relays:

In case of metal to carbon contact type relays, sealing shall be done at Manufacturer's
premises before dispatch and if the seals have to be broken due to any defect noticed,
resealing must be done at the workshops.
Fig 18: Sealing of Relays


2.4.4
Maintenance:





2.4.5
In case of metal to metal contact type relays, sealing of the cover shall be done by not
below the rank of JE(Signal) at site. Whenever seals have to be broken at site for
maintenance purposes, the same shall be done by an official not below the rank of
JE(Signal).
Line Relays shall be energized at the rated voltage specified in the specification.
Cleaning shall be done regularly so that dust is not deposited on the relay.
Ensure that there is no loose connection on the terminals and plug in relays are fitted
tightly & the sealing is intact.
Ensure that metal contacts are not blackened due to arcing. There is no pitting of
carbon contacts. No foreign materials or water vapour which can cause fungus
formation, are inside the relay. There is no rusting or sulphation on the parts.
Ensure that the relays are not due for P.O.H., wherever applicable.
During routine inspection and maintenance, if high contact resistance is observed on
any contact of a relay, spare contact to be used or the relay should be replaced.
Periodical Inspection:
Sectional SSE/JE (signal) shall visually inspect the relays, with particular attention to
those used in vital circuits. During visual inspection, relay shall be taken out of service if
any of the defects are noticed in respect of:
a)
Movement of armature and contact carriage
14
Handbook on Safety in Signalling 2.0
b)
c)
d)
e)
f)
g)
h)
i)
j)
k)
l)
m)
Wiping of contacts
Arcing of contacts
Pitting or charring of contacts
Dust accumulation on contacts
Electro-plating
Corrosion, rusting of components
Crack or breakage in components
Presence of fungus and ants inside the relay casing
Charring of cover near contacts in the case of plug-in-type relays
Corrosion of Label
Absence or tampering of seal
Effectiveness of relay retaining clip to be checked in case of Q Style Plug-in Type
Relays
n) Any other abnormal condition
2.4.6
Replacement:
Metal to carbon contact miniature plug-in type relays should not be overhauled. These
relays except track relays should not be used after completion of the Codal life of 25 to
30 years or after their failure. Plug in type track relays have to be replaced on completion
of 12 years or earlier if warranted by the actual condition of the relay and/or its usage.
2.5
2.5.1
Relay Room:
Precautions:
{Ref.: CAMTECH’s Publications “Maintenance Instructions on Relay Room”}


Ensure double locking arrangements in Relay Room.
Ensure entry in SM/s key register is made whenever SM’s key is required to open the
Relay Room. (This may be as per the prevalent Zonal Railway Instructions)
Fig 19: Double Locking arrangement
in a Relay Room
Fig 20: Double locking arrangement in Relay
Room of an Electronic Interlocking installation





Ensure nomenclature while replacing relay.
Check for proper fuses in the relay rack and no fuse is bypassed.
Check that each relay is properly plugged, clipped/bolted and sealed.
Do not tamper with the code pins of the relay while replacing.
Check for clean and neat soldering on tag block.
15
Handbook on Safety in Signalling 2.0



Don’t keep extra material/ loose wires inside Relay Room.
Ensure sufficient lighting arrangement in the Relay Room.
Ensure proper tightening of cable terminals on racks.
2.6
Control Cum Indication Panel (CCIP)/Control Panel:
2.6.1
Safety Requirements:
{Ref.: Section 7, Chapter 7, Para 7.7.2 & Section 1 Chapter 21, Para 21.1.2 of New SEM
(July-2021)}


The display of the layout on the front of the Control Panel shall be well proportioned,
and each track circuit shall be clearly distinguished by different colours.
A Control cum Operations Panel with Indications (CCIP or Control Panel) for route
switches/buttons, point switches etc. shall be provided in Geographical order.
However, a separate Indications panel and a separate operating panel may also be
provided for large installations for convenience.
Fig 21: Control Cum Indication Panel (CCIP)




The Route setting shall be on "Entry/Exit" principle for installations of Route Setting
type. Each route shall be controlled by means of two push buttons-one at the entrance
and the other at the exit of the route. In Non-route setting type installations, after
setting of the route by individual operation of points is completed, signal can be
cleared by an individual push button in conjunction with a group button or by an
individual switch
Controlling each signal or a common switch for conflicting signals which are not
required at the same time, or one push button at the entrance and other at the exit end.
SM’s Key control arrangement shall be provided on Control Panel/VDU, to prevent
any unauthorised operation.
Provision for emergency route release shall be provided on Control Panel/VDU. This
emergency operation shall be recorded through a Non resettable Counter incrementing
for every such operation.
16
Handbook on Safety in Signalling 2.0






All Emergency operations shall be two-step process, to safe guard against unintended
operations.
Locking and Sealing arrangements shall be provided for the covers of Control
Panels/Block Instruments etc. to secure against unauthorised opening. Relay Rooms at
stations shall be provided with double lock arrangements.
Individual push button in conjunction with a common push button or two/three
position switches shall be provided for individual operation of points.
Where a route has more than one overlap, it shall be possible to select and set the
desired overlap beyond the exit signal of the route.
Where the route has alternate approach routes, it shall be possible to select and set the
desired route with desired overlap.
The switches/buttons shall have distinctive colours so that they can be readily
distinguished, such as running signal red, shunt signal yellow, calling on signal red
with white dot & exit button white. The alternate overlap white with black dot,
alternate route Grey, point black, slot green, crank handle blue and point group button
black with red dot etc.
Fig 22: Switches/Buttons in CCIP
2.6.2
Do’s & Don’ts for Control Cum Indication Panel (CCIP)/Control Panel in
PI/RRI:
{Ref.: CAMTECH’s Publication’s on “Do’s & Don’ts for Panel Interlocked Station”}
2.6.2.1
Do’s:


Check that Emergency Point Operation (EWN) button and Emergency Route Section
(EUYN) buttons are sealed. If found not sealed, then check the entry in the concerned
register and ensure that it is correctly maintained, get it sealed and ascertain the cause.
Check that all the counters are working properly and in accordance with entries in
respective register i.e.
a)
b)
c)
d)
e)


EWN Counter Increments on each emergency point operation.
EUYN Counter Increments on each emergency route section release.
EUUYN Counter Increments on each emergency route release.
OYN Counter Increments on each overlap release.
COGGN Counter Increments on each calling-on signal clearance operation.
Check that, when SM’s key is taken out, it shall not be possible to do any operation
from Control Panel. Also ensure that the signal can be put back to ‘ON’ in this
condition without altering the route.
Check that the buzzer and ‘Push button/buttons have been left pressed’ indicator is
working.
17
Handbook on Safety in Signalling 2.0
Fig 23: VDU Monitor of Electronic Interlocking
Fig 24: Control Cum Indication Panel with push buttons



Always obtain a written memo from the on duty ASM before doing emergency route
section release by EUYN key or emergency point operation by EWN button.
Check that the panel indication for flasher is working properly.
Check that adequate numbers of button collars are provided on the operating panel.
2.6.2.2 Don’ts:




Don’t do any such operation on the panel, which interferes with the movement of
trains.
When the point zone track circuit is showing occupied indication, do not try to
operate the point with EWN button without ascertaining that track circuit is dropped
and no vehicle is standing on the track.
For testing of points, do not operate the points without getting consent from outdoor
staff on VHF set, mobile phone or group telephone.
Don’t break any seal without getting a written memo and entry being made in the
concerned register.
18
Handbook on Safety in Signalling 2.0


Don’t do any maintenance work in the Relay Room during the train movement in the
station yard.
Don’t do any cleaning / oiling maintenance work on points without the knowledge of
ASM panel and other works without having proper disconnection memo.
2.7
LED Signals:
2.7.1
Safety Precautions:

Don’t leave loose wires on input terminals of LED Signal lighting unit. This may
cause false operation.
 Don’t try to interchange connections of LED Signal lighting unit.
 Don’t try to give direct supply to the LED Signal lighting units without proper
installation.
 Do not try to open the unit as it is sealed for environmental protection.
 Check that selection in case of YELLOW signals have been configured in Blanking
mode for OFF aspects and Non-Blanking mode for ON aspects.
Note:
i. Selection of Blanking / Non Blanking mode is provided with protective cover.
(ONLY for YELLOW aspects)
ii. Selection for Blanking / Non Blanking mode is provided internally for RED and
GREEN aspects.
 Check the possibility of water seepage/leakage inside the Signal Units before the
onset of monsoon. Check that if leakage/seepage persists then plastic cover/canopy of
approved design is provided on the back of signal unit.
Note:
i. Where plastic cover/canopy is provided over signal unit to prevent
leakage/seepage, maintainer should check on each visit the condition of internal
wiring and components by opening the plastic cover/canopy and unit cover.
Fig 25: Plastic cover/canopy over Signal unit
ii.

A case has come to light where plastic cover provided over a route unit was not
checked during the whole monsoon period and the wiring was cut by rodents
resulting in unsafe side failure.
The rating of fuse provided on housing of Route Aspect shall be 100 mA 250 V
irrespective of all makes. (Please refer RDSO Technical Advisory Note No.
STS/E/TAN/2001 dated 04.06.2015 regarding Guidelines for fuse rating on Route
LED Signal Aspects.)
19
Handbook on Safety in Signalling 2.0
2.8
Block Instruments:
{Ref.: Chapter 18, Section 3 of New SEM (July-2021)}
2.8.1
Safety Precautions:









2.8.2
The Table or other fixture on which instruments are placed must be substantial and
the Instruments are securely fixed there on.
Block Instruments, Distinction of: Where two or more block instruments are located
in the same room, they shall be fitted with bell Units/bell buzzers of distinctive tones.
Line Wires: The line wires from the point where the lines of two adjacent block
sections meet to the terminating point on or near the building shall either be insulated
or be so erected as to be not less than 150 mm from any other wire. The insulated line
wires must be terminated on pot-head insulators. The line wires must not be easily
accessible.
Leading in Wires: The wires leading into the building from the terminating point
shall be adequately separated from the wires of other circuits and shall be single,
braided or metal sheathed, run in one length from the pothead insulator to the test
panel.
Lightning Dischargers shall not be located in the Block Instrument but installed
separately and shall be the demarcating point for test purposes.
It shall be ensured that induced voltage due to power line parallelism does not exceed
150 V and the short circuit fault current does not exceed 430 V as prescribed by
CCITT.
Since the immunity of PR relay is only up to 10 V, block filters shall be used in all
block instruments using this relay where this limit is exceeded.
A separate earth shall be provided for each instrument. The earth shall be of an
approved type and should be buried at a depth of not less than 1.5 m and at a distance
not less than 2.5 m from any other earth. The resistance of the earth should not be
more than 10 Ohms.
The length of the Earth wire shall be as short as possible and cross section of the wire
not smaller than the size of the line wire and in any case shall not be smaller than 4
mm dia. The earth wire shall not have a sharp bend or spiral.
Prevention of Irregular Operations:
There shall not be any opening giving access to the interior of the instrument through
which it is possible to operate the mechanism by any irregular means.
2.8.3
Locking and Sealing Facilities:
Facilities shall be provided for locking and sealing the Block instruments. The doors of
the Block instruments giving access to the internal mechanism shall be provided with a
double lock, the key of one of which shall be in the custody of the Station Master on
Duty and the key of the other will be with the technician signal in charge of the
maintenance of Block Instruments. It shall not be possible to open the door of the Block
Instruments without the co-operation of both the agencies.
20
Handbook on Safety in Signalling 2.0
Fig 26: Locking and Sealing of Block Instruments
2.8.4
Prevention of Unauthorized Operation:
A lock or other device shall be provided to enable the Station Master on duty to prevent
unauthorized manipulation of the instrument during his absence.
2.8.5
Overhauling of Block Instruments:
Periodical overhauling interval shall not exceed ten years for Single Line Token Block
Instruments and seven years for Double Line Block Instruments and Handle Type Single
Line Token Less Block instruments. Push Button Token Less Block Instruments, UFSBI
Block panel, and Embedded block working in Electronic Interlocking etc. do not require
overhauling.
2.9
Fuses:
{Ref.: Chapter 19 of New SEM (July-2021)}
2.9.1
Precautions:

Fuses shall be of approved type and appropriate rating. When fuse is not provided
with fuse blown off indication, additional indication circuit may be provided.
Fig 27: Fuse Auto changeover system with indications



At the time of commissioning of any signalling installation, the normal load current of
every circuit shall be measured and recorded. These recorded values shall be checked
with the theoretically obtained values. Fuse of correct capacity which should be not
less than 2.5 times the rated current, shall be provided.
When there is a case of fuse blowing off, the concerned circuit current shall be
measured and compared with the original recorded value. If there is a variation, action
shall be taken to locate and remove the defect before a new fuse is inserted.
For LED signal aspects, fuse of prescribed rating (0.6 Ampere if not prescribed
otherwise) shall be used.
21
Handbook on Safety in Signalling 2.0
2.10
Earth Leakage Detectors (ELD):
2.10.1 Precautions:
(Ref.: New SEM Chapter 15, Annexure: 15-MS2)






2.11
All cable terminations are tight & properly connected
in ELD.
All cables termination devices, pillar boxes, cable
heads and glands shall be kept clean and dry.
Checking the ELD equipment free from dust.
Check & ensure that fault totalizer (counter) of each
channel increase after each reset operation.
Fig 28: Earth Leakage Detector
Ensure earth connection soldered on earth side for
(ELD)
corrosion free connection.
Check Data Logger messages are generated after creating false earth faults during
inspection by SSE/JE (Signal).
Integrated Power Supply System:
2.11.1 Safety Precautions Before Commissioning of IPS:
Authorized, qualified and skilled electrical technician should only attempt installation,
testing, fault location and repair of this IPS system. The equipment carries dangerous
voltages and stores electrical energy. Before touching any live parts remove metal
objects, e.g., metal bracelets, rings or a watch that may come into contact with electricity
carrying items. Carry out the following instructions.
i.
ii.
Switch-off the AC main supply external to the equipment.
Check with a suitable voltmeter fitted with insulated test probe that the equipment
does not carry any voltage at either the input or the output before commissioning
work.
The above instructions must always be followed before making any adjustment, and also
before making any electrical connections to the part of the equipment for the purpose of
servicing. Such connections should always be checked for safety before re-applying
power. The above instructions must also be carried out before any connection is modified
or removed.
Note:
 Adjustment should only be carried out with a non-conducting tool taking care not to
touch any item carrying electricity while doing so.
 The initial installation of IPS Unit should be done by technically trained staff and
under the supervision of the Firm’s representative. Also it is recommended that the
operation of the unit be entrusted to a trained person only. Since the IPS unit has
230V AC input and 110V DC outputs. Initial inspection and preliminary check out
procedure are recommended for safe operation. Before switching on the IPS, all the
connections shall be checked as per the interconnection wiring diagram.
Important Note: Please do not change the setting of potentiometer/Preset before switching on
the unit.
2.11.2 Safety Precautions During Maintenance:
2.11.2.1 FRBC Module:


Do not take out plugs of modules when working.
Do not connect battery when modules are on.
22
Handbook on Safety in Signalling 2.0


Do not connect battery in reverse polarity.
Do not disturb battery under voltage cut-off setting.
2.11.2.2 Inverter Module:


Do not remove input / output connectors when unit is on.
Ensure correct DC polarity to Inverter input.
2.11.2.3 DC-DC Converter:



Do not switch-off any of the modules of a group of DC-DC converters.
Do not set unequal voltages of the DC-DC converters of the same group.
Do not remove the flat cable connected to a DC-DC converter.
2.11.2.4 AVR Module:

Do not Run AVR at no load.
2.11.2.5 Transformer Module:



Do not Short output of transformer.
Always, ensure 230V supply to transformer.
Always, load only up to rated current.
2.11.3 General precautions:






Always use tools such as screw drivers, pliers etc. with
insulated handles.
Use rubber mat and rubber gloves while working on a module.
Do not use wire fuses.
Do not disturb the factory adjusted potentiometers used in
PCBs.
Check temperature of Room/Shelter regularly. It should be less
than 50 deg. C.
Do not connect Battery Bank to IPS without removing
the battery fuse.
Fig 29: Integrated Power Supply
System
2.12
Low Maintenance Lead Acid (LMLA) battery:
2.12.1 Safety Precautions:
{Ref.: CAMTECH's Handbook on Lead Acid Cell (March 2005)}
2.12.1.1 During Transportation and Initial Charging of Batteries:







Don't mishandle the cells specially during transportation.
Don't hold the cells by the electrode terminals.
Always use rubber gloves and goggles and wear an apron while
working with battery electrolyte.
Always pour acid into water and not vice versa.
Ensure that the positive and negative wires are connected to positive
and negative terminals respectively, while connecting the charger to
the battery set.
Ensure that float indicators are available and in working order.
Ensure that there is no leakage of electrolyte from the cell, due to
crack in the container of the cell.
Fig 30: LMLA Battery
23
Handbook on Safety in Signalling 2.0


Cans or metal jugs should not be used for carrying water required for topping up the
cells.
Electrical connections should always be kept tight. Loose connection causes failure
and may cause sparking.
2.12.1.2 During installation:

















Mount the batteries in well-ventilated, clean and dry rooms.
For small battery installations, natural ventilation through windows and doors may
normally be sufficient. However, for larger battery installation (more than 12 cells).
Forced ventilation methods using exhaust fans must be provided.
Separate battery room are necessary to avoid the adverse effect of fumes on other
interlocking and power equipment as well as to provide
free access to the maintenance staff (battery rooms are
not double locked.).
The battery room shall be provided with acid proof
flooring and acid proof tiles on walls up to suitable
height.
Wherever, batteries are kept in field inside the location
boxes, suitable openings/holes are necessary for
ventilation.
Where batteries are housed in location boxes, these
housings shall be painted with acid resistant paint.
Fig 31: Battery Room
In some applications, where a few cells are required to be kept
in offices, equipment rooms, residence etc. they may be
housed in wooden boxes proved with enough holes for ventilation.
Locate the batteries away from direct Sunrays and heat emitting system.
Place the batteries on rugged wooden racks of sufficient height so that it is possible to
inspect and maintain them properly.
Two or more coats of acid resistant paint of approved type shall protect the racks.
The racks shall be level and mounted on approved type of insulators.
The cells shall be installed as per approved drawings.
Insulate the cells from the floor and from each other using insulators. Place wooden
planks under the batteries wherever the cells are kept on masonry racks and floors,
metallic frames and location boxes.
Keep the individual batteries properly aligned and levelled to avoid stress on the
connectors/cable. Keeping battery insulator block under the battery is desirable.
Ensure proper clearance between adjacent cells for connecting the battery terminal
connectors and between adjacent rows from the angle of maintenance.
Wooden battery racks must be protected against decay by painting them using acid
resistance paint (Type 2 of IS 158-68).
On receipt of charged secondary cells, the vent plugs shall be removed and the height
of the electrolyte shall be noted, if it is below the prescribed level, the loss may be due
to spillage during transit. The level of the electrolyte can be restored by adding battery
grade acid of recommended specific gravity.
2.12.1.3 During Maintenance:

Maintenance tests and repair work on the cell, which may interfere with safe
operation of trains, shall not be started until movements are fully protected.
24
Handbook on Safety in Signalling 2.0














2.13
Temporary repairs or adjustments shall be made in such a manner that safety of train
operation is not impaired when repairs and or adjustments are made.
After the maintenance and repair work (Including temporary repair) are completed
tests shall be immediately carried out to ensure that the connected apparatus functions
satisfactorily.
Checks/tests on battery and general cleaning normally do not affect the circuit it is
feeding. However, care must be taken to ensure that the working circuits do not get
affected.
For maintenance and repair works (including temporary repairs) which may require
disconnecting or recharging or replacement of the battery, disconnection notice must
be issued to the ASM on duty and work commenced after the same is allowed and
necessary precautions have been taken. This will ensure safety in train operation.
Always use suitable goggles and rubber gloves and wear an apron while working with
battery electrolyte.
The vent plugs should be kept in position and tight. If a vent plug is lost, it should be
replaced early to prevent spillage of electrolyte.
Only approved hydrometer and Voltmeter should be used for recording observations.
Electrolyte is highly corrosive and should be handled carefully to avoid injury to
person or damage to clothing or equipment. If the electrolyte is accidentally spilled, it
should be flushed with plenty of water immediately, after treating with washing soda
solution.
Do not allow open flame smoking near the batteries to eliminate danger from
explosion or fire.
Extreme care must be exercised to avoid a spark or flash when changing connections
or working on or near the battery.
Battery lead should first be disconnected at a point remote from the battery set.
Metal jugs should not be used for carrying water required for topping up.
Do not mishandle the cells, Specially during transportation.
Do not hold the cells by the electrode terminals.
Precautions for Valve Regulated Lead Acid (VRLA) Battery:
2.13.1 Safety Precautions:
{Ref.: Pamphlet on VRLA battery (July 2007)}








Avoid sources of heat or cooling directed on to the
batteries.
Check that the physical condition of batteries is good i.e.
there are no cracks, bulges and heating marks on it.
The battery room and location boxes should be kept well
ventilated and free from water, oil and dirt.
Since the voltage to be measured require an accuracy of
0.05 V, only digital multi-meters are to be used for this
purpose.
Do not exceed the charging voltage above 2.30 V per
cell maximum per cell.
Do not open the safety valve for adding water or acid.
Do not attempt to dismantle the battery.
Do not boost charge the batteries for more than 12 hours.
Fig 32: Valve Regulated Lead Acid
(VRLA) Battery
25
Handbook on Safety in Signalling 2.0


2.14
Do not mix ordinary conventional low maintenance batteries with maintenance free
VRLA batteries.
Do not tamper with the cell vent.
Signalling Cables:
Cables for signalling circuits shall be of approved types.
2.14.1 Safety Precautions:
{Ref.: Chapter 15 of New SEM (July-2021)}
2.14.1.1 For Cabling:



While planning for Cabling on a route, the number of conductors required, depending
upon the circuits should be first determined. Recommended core sizes as per
specifications shall be used.
Where a number of cables have been laid along a route, the circuits shall be so
distributed that cables can be disconnected for maintenance purpose with the least
possible dislocation to traffic.
As far as possible low lying areas, platform copings, drainages, hutments, rocky
terrains, points and crossings, shall be avoided. Proximity to Electrical Sub
Stations/Switching stations shall be avoided.
2.14.1.2 For Storage and Transportation of Cable:

Cable drums shall not be stacked on flat side. Suitable stoppers shall be placed for
stability.
Fig 33: Storage of cable drums

When rolling the cable drum either for unloading or transportation, the drum shall
always be rotated in the direction of the ‘arrow’ which is marked on the drum.
Fig 34: Rolling of cable drums

During all stages of storage, it is essential that the ends of the cable are effectively
sealed by end cap or in any other approved manner to avoid water entry into the cable.
26
Handbook on Safety in Signalling 2.0
2.14.1.3 For Paying Out and Testing of Cable:

For paying out cables, the cable drums shall be mounted on cable wheels. It should be
ensured that no kink is formed while paying out the cable.
Fig 35: Cable wheels for mounting of cable drums


Before the cable is laid in the trench, a visual inspection of cable shall be made to see
that there is no damage to the cable. It shall be tested for insulation and continuity of
the cores.
Whenever mechanized equipment is used, the work shall be carried out by a trained
operator under the supervision of SSE/JE(Signal), in charge of the work.
2.14.1.4 For Laying of Cables:



The main cable laid parallel to the track shall normally be buried at a depth of 1.0 m
from top of cables to ground level, including those laid across the track (1.0 m below
the rail flanges). The depth shall not be less than 0.50 m for tail cables. In theft prone
areas, the cables may be laid at a depth of 1.2 m with anchoring at every 10 m.
The ducts being used shall be of such design and length to prevent/minimise damages
to cable by any other future digging activities in the vicinity. The ducts shall have
suitable covers to prevent water collection in the duct.
Cables belonging to other department must not be laid in the same trench along with
Signal & Telecommunication cables.
a) A distance of approximately 10 cm must be maintained between cables of other
department and signalling cables.
b) The signalling cables must be separated from LT power cables by a row of bricks
or any other approved means and from HT power cables a minimum of 3 m
separation shall be maintained.

Where several cables of different categories have to be laid in the same trench, they
shall be placed as far as possible in the following order starting from the main track
side, so that in the event of failures, the maintenance staff may easily recognise the
damaged cables.
a) Telecommunication cable
b) Signalling cable
c) Power cable

Signalling cables for outdoor circuits should not normally be laid above ground. In
exceptional cases where it becomes unavoidable, the following precautions should be
taken:
27
Handbook on Safety in Signalling 2.0
a) The cable should be suspended in wooden cleats, from cable hangers or in any
other approved manner so that no mechanical damage occurs to the cable even
under exposed condition.
b) The cable supports shall be so spaced as to avoid sag.
c) In station yards, cable shall be laid in ducts suitably protected.
d) Indoor signalling cable should normally be laid on ladders, channels or in any
other approved manner. The cables should be neatly tied/laced.


Where it is necessary to take the cable between the tracks, it shall be carried in
trunking/Duct/pipe kept sufficiently below the ballast level.
While laying the cables in accordance with the above instructions, the following
instructions should be adhered:
a) Outside the station section, the cables should generally be laid at not less than 5.5
m from the centre of the nearest track.
b) Within the station section, the trenches shall preferably be dug at a distance of not
less than 3 meters from the centre of the track, width of the trench being outside
the 3m distance.
At each end of the main cable an extra loop length of 6 to 8 m should be kept.
After laying the cables, back filling of the trenches should be done properly. The soil
excavated shall be put back on the trench, rammed and consolidated.
Where the cables are entering the Cable room/Relay Room/apparatus case etc., the
cables shall be firmly held with suitable clamping arrangement, so as to avoid
downward displacement.
c)


2.14.1.5 For Testing of Cables:

Periodical Testing of Signalling cables shall be as under;
a) First measurement of insulation of the cable should be carried out after laying of
the cable and after first monsoon for all the conductors.
b) After major work in a yard, all cables should be meggered afresh.
c) In all other cases, Insulation Resistance shall be tested periodically as given
below:
Table 1: Insulation Resistance Testing Periodicity of Signalling Cables


Type of Cable
Periodicity
Main Cable
Every 2 years
Tail Cables – Signal/Track/Points etc
Once in a year
Spare Conductors
Once in a year
No excavation in the vicinity of underground signal cables shall be undertaken
without a representative of the signal & telecommunication department present and
without taking suitable precautions for the safety of the existing cables. Suitable
instructions in this regard shall be issued by the Railway in the form of a joint
circular.
The protective works provided for the cables at places like track crossings, culverts,
bridges etc. shall be regularly inspected by the maintenance staff, special attention
being paid to these protective works soon after the monsoon.
28
Handbook on Safety in Signalling 2.0

2.15
Earth Leakage Detector (ELD): Shall be provided in all signalling installations and
shall be interfaced with Data logger (wherever feasible) for remote monitoring.
Earthing, Lightning & Surge Protection Devices:
2.15.1 Earthing:
Earthing of cables, equipment, buildings and structures is done for one or more of the
following purposes:
a) Lightning & surge protection of equipment.
b) Earthing of metal screens of telecommunications cables and equipment for reducing
Electromagnetic interference.
c) Human safety.
2.15.1.1 Precautions:
{Ref.: Para 19.11.3 of New SEM (July-2021)}














The lever frame and other metallic frames of the cabin shall be earthed.
The earthing shall be provided at every location box where cables terminate.
The earthing shall be provided at each signal.
Wherever possible, the common earthing system to be provided for closely located
location boxes, signal posts, etc. Separate earth is required for equipment requiring
functional earth only.
Sheath & Armour of Main cables to be earthed. Armour of OFC shall be earthed at
both ends. It is not necessary to earth the armouring of unscreened cables when they
are used as a tail cables except in special cases where the length of the tail cable
exceeds normal prescribed limits.
In case of signals falling within 2 m from the electrified track, the protection screen
shall be connected to an earth.
There shall not be any possibility of simultaneous human contact with metallic bodies
connected to different earths, where it is not possible to provide suitable spacing or
partition between various metallic objects referred to above, they shall be connected
to a common earth.
Common/Equipotential earth for modern electronic equipment such as EI, DAC, Data
logger etc. to be used in Relay Room. Earth value shall not be more than one ohm and
shall be measured annually during dry season.
Earthing wires from subsystems to earth terminal shall be of distinctive colour. Green
or Green Yellow (GNYE) colour is recommended for quick identification of a loose
or disconnected earth wire.
All earth wires shall be as straight as possible and shall never be coiled.
Earth wires should be of adequate current carrying capacity and should not be less
than 4 Sq. mm copper cross-section or its equivalent.
Earth resistance up to 10 Ohms is normally permissible for protective earth except
when specified otherwise. For electronic equipment, Earth resistance shall not be
more than One Ohm.
Earthing of approved type shall be provided for each block instruments and other
signalling equipment at a station. Dedicated earthing arrangement to be provided for
earth return circuits individually if any.
The resistance of earth for signalling circuits shall not exceed 10 Ohm or as
prescribed by OEM/RDSO. If the resistance is more than the required value, steps to
reduce the earth resistance shall be taken. If it is still not possible to reduce the value
29
Handbook on Safety in Signalling 2.0

below the required value, even with the adoption of these methods, additional earths
may be provided in parallel.
Where more than one earth electrode is used, the distance between two earthing
electrodes shall be as per approved design.
2.15.1.2 Regular Checks/Upkeep of Earths:
{Ref.: Para 19.11.9 of New SEM (July-2021)}
 Block earths and their connections shall be examined at intervals of not more than
One Month by JE (Signals) and not more than Three Months by Sectional
SSE(Signal)/In charge.
 Block earths shall be tested for resistance at intervals of not more than 12 Months by
Sectional JE/SSE (Signal). Where the resistance exceeds 10 Ohms, action shall be
taken to reduce the resistance by providing additional earths in parallel.
 If routine testing indicates that existing earth electrode system is not satisfactory, a
new earth electrode system (or part of a system to supplement the existing system)
shall be provided.
2.15.2 Lightning & Surge Protection Devices (SPD):




Lightning occurs throughout the world, but some areas receive far more lightning than
others. A single direct strike can result in physical damage to the structure which may
result fire, loss of product, damage to infrastructure, communications downtime and
loss of life. Lightning also poses unacceptable risks for electronics and
communication systems.
A surge is a very short burst of voltage, which if not suppressed, can cause equipment
failure or lockup. The duration of surge is less than 1/1000 of a second. Surges are
induced in nearby AC power lines due to cloud to cloud and cloud to ground strikes.
Surges are also generated due to self-inductance whenever power is switched on or
off during a non-zero crossing point of the sine wave.
Surge Protection Devices can protect the electronic equipment from the potentially
destructive effects of high-voltage transients.
2.15.2.1 Protection of S&T equipments:
{Ref.: CAMTECH publication on Earthing & Surge Protection devices for S&T
installations, December 2017)}


Equipotential bonding to be provided for all the equipment for effective lightning and
Surge protection in Signal Equipment Rooms, such as End Goomties/cabins.
Nowadays almost all equipments used in S&T department include the electronic
devices which operate on low voltages. The low voltage equipments e g. UPS, Battery
Charger, Inverter, control systems, etc are provided with surge components like
MOVRs avalanche diodes, gas discharge tubes etc. inside the equipments. The
internally used surge protection components prove to be inadequate towards the surge
protection solution. Hence to protect these devices from transient over voltages
produced due to lightning, switching of inductive loads, ignition and interruption of
electronic arcs etc., suitable surge protection arrangement is required to be done at
different levels.
30
Handbook on Safety in Signalling 2.0
2.15.2.2 Function of SPD:


Surge protection devices should ideally operate instantaneously to divert a surge
current to ground with no residual common-mode voltage presented at the equipment
terminals.
Once the surge current has subsided, the SPD should automatically restore normal
operation and reset to a state ready to receive the next surge.
2.15.2.3 Lightning protection levels:
 Protection against the lightning on the structure housing the equipment:
This type of protection is classified under Class ‘A’ protection:


This is provided with an external lightning conductor or Early Streamer Emission (ESE)
Air Terminal on top of the building connected through a down conductor to ground
(EARTH). This is known as class ‘A’ protection.
By this arrangement 50% of lightning energy is connected to ground. Depending on the
area, size of the structure to be protected and the type of protection varies.
Fig 36: Class ‘A’ protection
Fig 37: A typical Early Streamer Emission (ESE) Air Terminal
 Power line protection:
31
Handbook on Safety in Signalling 2.0
The power line of electronic signalling equipment shall have Class B & C type 2-stage
protection. Stage 3 protection is also required for protection of power/signaling/data
lines. Class ‘B’ and class ‘C’ type protection devices shall preferably be pluggable type
to facilitate easy replacement.
32
Handbook on Safety in Signalling 2.0

Stage 1 (Power Line Protection at Distribution level)/ Class ’B’
protection:
The first stage of protection provided before the equipment at
mains distribution panel is called class ’B’ type.
Fig 38: A Class ‘B’ SPD

Stage 2 (Power Line Protection at Equipment level)/Class- ‘C’
Protection:
This type of protection is provided against low voltage surges at the
equipment input level connected between line and neutral.

Fig 39: A Class ‘C’ SPD
Stage 3 (Protection for Power/Signalling/data lines):
All external Power/Signalling/data lines (AC/DC) shall be protected by using preferably
pluggable stage 3 surge protection devices which consists of a combination of
varistors/suppressor diodes and GD tube with voltage and current limiting facilities.

Protection of Power line/ Class ‘D’ protection:
This has an indication function to indicate the prospective life and
failure mode to facilitate the replacement of failed SPDs.
Fig 40: A Class ‘D’ SPD

Signalling/Data line protection:
These devices shall preferably have an indication function to indicate the prospective life
and failure mode to facilitate the replacement of failed SPDs.
If the device has any component which comes in series with data/signalling lines, the
module shall have “make before break” feature so that taking out of pluggable module
does not disconnect the line.
33
Handbook on Safety in Signalling 2.0
Section-3
Safety in Modern Signalling installations based on Electronics &
Communications
34
Handbook on Safety in Signalling 2.0
3.1
Data Logger:
(Ref.: CAMTECH’s Publication “Handbook on study of Data logger reports”)
3.1.1
Do’s and Don’ts:
3.1.1.1 Do’s:




Install the CMU in a Dust free and cool environment.
Please assure that the system is running, with the NMDL
software, round the Clock.
Assure from time to time that the system has enough free
space in the ‘C’ Drive.
Regularly at least once in 3 months, take a copy of the
previous 3 Months database in a CD.
3.1.1.2 Don’ts:




Do not open Floppy’s/ CDs in the CMU without
confirming that they are Virus free.
Do not use the CMU for other software like Signal failures
entry/Signal incidence software/ Auto CAD etc. as the
system setting required for NMDL Modules may be
disturbed.
Do not install Games/Screen savers/wall papers etc. they
Fig 41: Data Logger
may occupy maximum RAM, disturbing the proper
working of NMDL Modules.
Do not Shutdown the system without proper close of NMDL and other Modules.
3.2
Axle Counter:
3.2.1
Axle Counter Resetting - Block Section/Intermediate Block Signalling/
Automatic Signalling:
{Ref.: Para 17.7.4 of New SEM (July-2021)}

Preparatory reset arrangement shall be provided, so that whenever the axle counter
shows fault condition; the same can be reset by the on duty Assistant Station
Master/Station Master, after ensuring that the monitored portion is clear of vehicles.
Fig 42: Digital Axle Counter
35
Handbook on Safety in Signalling 2.0

The following precautions shall be followed for resetting:
i. Once the Axle Counter has failed and the concerned signal cannot be taken off, the
on duty Station Master (ASM) of Train dispatching station shall positively verify
the clearance of the block section with the on duty Assistant Station Master (ASM)
of Train receiving station by exchange of private numbers and record the same in
Train Signal Register (TSR) by both the stations. After ensuring that the block
section is clear of vehicles, Axle Counter`s reset operation shall be initiated by
cooperative effort between the ASM`s of the dispatching and the receiving stations.
ii. The circuitry shall be such as to obviate the possibility of the resetting by the
dispatching/receiving station independently.


3.2.2
The reset box shall be operated by a key which shall be kept
locked in a separate box kept in the SM’s office. Each and
every operation of the reset button shall be counted on a nonresettable type counter and shall be recorded in the Train Signal
Register by both the SMs, indicating the movement before and
after the operation of the reset button. During inspection of the
stations the Signal and Traffic Inspecting officials shall
specifically check-up and ensure that the system of exchange of
Fig 43: Reset box
private number is being followed meticulously.
The procedure of resetting, verification of clearance of concerned
axle counter section from any obstruction/vehicles before resetting is initiated and
piloting of the first train shall be clearly laid down in the Station Working Rules.
Axle Counter Resetting - Station Section:
{Ref.: Para 17.7.5 of New SEM (July-2021)}
Where Axle Counter is provided in station section, the following procedure shall be
followed for resetting:
a) Cooperative Type for Point Zones/Loop Lines/Siding: Once the Axle Counter has
failed and is showing fault condition, the on duty ASM/ Station Master (SM) shall
first arrange to verify that line on which train is to be received is physically clear of
any obstruction. Such physical verification of failed Track section shall be done
through Line verification box (LV box) which shall be installed close to the line to
be verified. The resetting shall be cooperative and done jointly by the on duty ASM
along with another Operating Staff, who shall verify physical clearance of Line and
operate the line verification box for the failed Track section of axle counter.
b) Main lines/Run through lines: Preparatory reset arrangement shall be provided.
c) The reset box shall be operated by a key which shall be kept locked in a separate box
secured in the SMs office. Each and every operation of the reset button shall be
recorded in the Train Signal Register by the ASM and during inspection of the
station; the Signal and Traffic inspecting officials shall specifically check-up the
procedures being followed in respect of the above resetting device and ensure that
laid down procedure for resetting is being followed.
d) This procedure of ensuring that the monitored portion is free of any vehicle before
resetting is done, shall be clearly laid down in the Station Working Rules.
e) The first train after the reset operation may be either received on calling-on signal or
piloted as per the extant rules after verification of the clearance of the reception line.
36
Handbook on Safety in Signalling 2.0
f)
If Axle Counter cannot be reset, due to any reason or it fails again after resetting, it
should be treated as failed and the Signalling maintenance staff should be advised
immediately for rectification.
Table 2: An Overview of Axle Counter Resetting Arrangements
S.NO.
Line/Section
(1)
Type of Reset
(2)
To be applied
by
(3)
1.
Preparatory Reset
Block Section/
Automatic
Signalling Section/
IB Signalling Section
On duty ASMs
at both ends of
Block Section
2.
Station Section/
(a) Main line/
Run through lines
Preparatory Reset
On duty ASM
and another
operating staff
(b) Point zones/
Loop lines/Sidings
Conditional Reset
On duty ASM
and another
operating staff
Axle Counter
status after
application of
Reset
(4)
After operation in
Column (3) and
Axle Counter will
show ‘Clear’ only
after tallying ‘Count
in’ with ‘Count out’
by the passage of
first Train.
-do-
Will show ‘Clear’
after operation in
Column (3)
*For Station Section: Once the axle counter has failed and is showing fault condition, the
first train shall be piloted as per extant rules, after verification of the clearance of the
reception line. After the piloted train has cleared the portion being monitored by the axle
counter, the axle counter may be reset. The reset device shall be operated by a key which
shall be kept locked in a separate box in the SMs office. Whenever, it becomes necessary to
operate the reset device, the resetting shall be done jointly by the on duty ASM along with
another Operating staff.
3.2.3
Do’s and Don’ts:
3.2.3.1 Do’s:


The Indoor equipment of the axle counting system shall be protected unauthorised
access.
Installation, Calibration and functional testing shall only be performed with the tools
prescribed and by qualified staff.
3.4.3.2 Don’ts:



Trains runs must not be performed over the assigned wheel detection equipment while
calibrating Axle Counter.
Do not use power supply provided to axle counter for any other application as it may
disturb functioning axle counter system.
Do not open the electronic junction box in rainy season unless very emergency and
should be covered to protect from moisture.
37
Handbook on Safety in Signalling 2.0




3.3
3.3.1
Universal Fail Safe Block Interface (UFSBI):
Do’s and Don’ts:









3.4
Do not carry out any testing activity on quad cable when connected to counting head
to prevent short circuit.
Do not attempt to repair any of damaged boards or components at site, send it to Firm
for repairing.
Do not handle any of the boards without following necessary precautionary features.
Do not spare boards at wet locations as it may affect characteristics of components.
UFSBI system is to be operated or maintained only by trained persons.
No attempt is to be made to operate the equipment at
Battery Voltage ranging below 19.2 V and above 28.8 V
DC.
Connectors or PCBs is to be plugged in or out after
switching off the power supply.
“RESET” should not be applied in case of “Link Failure” or
“Supply” Break Down.
Replacement of components or modules is to be done with
spares supplied/prescribed by the manufacturer.
While plugging in/out a PCB, care is to be taken to avoid
application of excessive force.
Arbitrary grounding should not be done to any “Common”
terminal inside.
Relay testing should not be performed involving forced
Fig 44: UFSBI
‘pick-up’ or ‘drop’ while the instrument is “ON”.
Standard restrictions against mishandling and opening of block
instrument are applicable also to UFSBI.
Electronic Interlocking:
{Ref.: UM 6800C –Microlok II – Start Up & Maintenance}
3.4.1
Safety Precautions:



3.4.2
When handling any circuit board or board component, observe all Electrostatic
Discharge (ESD) Precautions. Improper handling of boards or components may result
in damage to static sensitive circuitry.
Do not install or remove any printed circuit board with power applied to the system.
Damage to the circuit board or the card file backplane may result.
Do not attempt to repair any EI system Printed Circuit Board or peripheral device in
the field. This equipment must be returned to the manufacturer for repair or
replacement. Any attempt to repair the EI system may jeopardize the safety related
functions of the system.
Electrostatic Discharge Precautions:
When working on the Electronic Interlocking System, contact with the system printed
circuit boards cannot be avoided. Hence following guidelines to be observed:

Always stand on an approved conductive floor mat when touching or handling printed
circuit boards.
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Handbook on Safety in Signalling 2.0






Always wear a strap grounding device. The wrist strap should have a 1.0 M Ohm
current limiting resistor. Connect the wrist strap grounding connector to suitable
ground connection.
Periodically check each wrist strap for continuity using an approved tester. Continuity
readings must be between 500 K Ohms and 10 M Ohms. Discard any wrist strap that
does not meet this criterion.
Always handle printed circuit boards by the edges. Do not touch board components.
Keep the work area clean and free of debris. Avoid using non-conductive materials
such as Styrofoam cups, plastic ashtrays, cellophane wrappers, or plastic covered
binders in the vicinity of the cards and modules.
Once removed from the card file/rack, immediately place printed circuit boards into
an anti-static conductive-shielded bag. Wrap the bag in conductive foam to protect the
circuit board during transport and shipment. Modules fitted with batteries may require
special packaging.
Avoid wearing clothing made of synthetic fabric when handling modules. Cotton
overalls are preferred.
3.4.2.1 Packing:
All plug-in modules and cards shall be packaged in anti-static packaging to prevent
damage to Electro-Static Sensitive Devices (ESSD) from electro-static discharge. When
so packed, the modules may be stored and transported without further precaution.
3.4.2.2 Storage:
For storage of Modules and cards following precautions shall be taken:
a) Must not be in close proximity to magnets, e.g. Automatic Warning System (AWS)
magnets.
b) Must be protected from damage due to electrostatic discharge.
c) Must be protected from the environment including physical handling damage.
d) If many modules are involved, it is permissible to use conductive card frames or
racks. However, bags and wraps are preferred.
3.4.2.3 Transport:
The equipment or modules must not be transported in close proximity to magnets e.g.
AWS magnets.
3.4.2.4 Handling Lithium Batteries:
Following precautions should always be observed while handling Lithium Batteries:


Packaging: Package all modules with batteries in a non-conductive anti-static bag. An
electrically conductive bag may short the battery terminals causing premature discharge
of the battery.
Damage: The lithium batteries contain very highly corrosive electrolyte. If a battery is
damaged:
a) Ensure unnecessary personnel do not enter the affected area.
b) Ventilate the immediate area.
c) Avoid contact with any liquid or internal components by wearing the appropriate
safety equipment.
d) Thoroughly wash the affected area with clean water and allow it to dry.
e) Return the module that may have been in contact with the electrolyte to the firm for
inspection duly packaged with an appropriate safety warning.
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Handbook on Safety in Signalling 2.0
 Disposal:
a) Dispose of the battery according to the local regulations.
b) Do not Short the terminals together.
c) Do not attempt to recharge.
d) Do not crush.
e) Do not disassemble.
f) Do not incinerate or heat above 100o C. (212oF)
g) Do not attempt to solder the cell.
3.4.3
Do’s and Don’ts:
3.4.3.1 Do’s:







To avoid possible damage to the diagnostic computer when connected to the
Electronic Interlocking equipment, if the power supply of the diagnostic computer is
connected to an AC power source, isolate the power source from earth ground by way
of a 3-prong to 2-prong adapter.
Before powering up the Electronic Interlocking equipment, ensure that there is no
train entering into the section in both Up and Down Direction.
Check the SPD Health Indication i.e. whether indication Glowing or Not in EI-Relay
Room & EI IPS Room Periodically.
Ensure Maintenance Terminal PC is always ON and verify the Event Data Log
Updates.
Periodically change over to STANDBY System by shutting Down the ACTIVE
System Quarterly as per prescribed change over procedure.
Observe all Electrostatic discharge precautions while handling any Printed Circuit
Board or board component.
For repair or replacement if any, return the equipment to the firm.
3.4.3.2 Don’ts:















Use Radio equipment within the immediate vicinity of Electronic Interlocking system
as Radio transmissions can affect electronic equipment.
Make circuit alterations or repairs to the Electronic Interlocking system.
Install or remove any printed circuit board with battery power applied to the system.
Try to troubleshoot without training.
Use Walkie-Talkie, Mobile Phone or any Radio Equipment Near EI Equipment.
Switch off any of the EI-IPS modules when EI is in operation.
Remove Modules, Fuses or connectors when EI is in operation.
Forcibly Pickup any Relays in EI Room/Field.
Remove any EI Relays.
Touch the board components/repair on your own.
Change computer setting/Applicatin Data without Prior Approval.
Distube OFC cable or connector.
Switch OFF MT-PC/Loading any software/Files.
Use Removable Media/USB/DVD/CD in VDU & MT-PCs.
Attempt to repair any Electronic Interlocking system printed circuit board or
peripheral device in the field.
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Handbook on Safety in Signalling 2.0
3.4.4
Do’s & Don’ts for dual VDUs:
3.4.4.1 Do’s:

Ensure that one VDU is in working mode and other VDU is in standby mode.
Fig 45: Normal & Standby VDUs of Electronic Interlocking installation





Ensure that SM’s Room is clean and dust free.
Download the backup of VDU logs at regular intervals (weekly basis).
Ensure that at least one successful changeover of online system to standby system is
done on bi-weekly basis.
Provide USB access lock software in both the systems to protect against virus.
Ensure SM’s Key is out while leaving VDU operation. This will prevent unauthorized
person to issue command in absence of the person authorized to perform operation.
3.4.4.2 Don’ts:








Shutdown both VDU systems together.
Remove any cables connected to VDUs.
Place any objects/container/eatables in and around embedded computer or monitors.
Keep liquid or fire prone items close to VDU system.
Delete any file and log from NVP folder without authorization.
Insert pen drive/USB without authorization.
Install and keep antivirus software or unnecessary software and files in both VDUs.
Leave the VDU unattended while SM Key is IN. Don’t shutdown VDU system at any
time.
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Handbook on Safety in Signalling 2.0
Section-4
Fire Safety in Signalling
42
Handbook on Safety in Signalling 2.0
4.1
Introduction:

At any working place, fire may occur due to negligence in safety precautions, human
error, equipment failure and various other causes. Fire at important S&T installations
like PI, RRI or EI may cause one or more of the following:
a) Damage to costly installation like Relay Room, Operating panel & Power Supply
system.
b) Paralyzing complete signalling system
c) Disruption in automatic train operation
d) Severe detention to trains lasting several days
e) Loss in terms of man hours due to deputing of additional task force to restore or
install a new system.
f) Heavy financial loss to Railways due to above.
g) Loss of life.





The above losses can be prevented up to a great extent if certain safety precautions are
observed. For prevention of fire at work places and firefighting in case of
emergencies, the following Precautions are necessary:
Vigilance & observance of Safety precautions.
Basic knowledge of using firefighting equipments.
Basic knowledge of first aid.
Training of staff.
In the wake of fire incidence at RRI Itarsi of Bhopal Division West Central Railway on
17.06.2015, the following recommendations were given by enquiry committee:
4.1.1
Recommendations/Suggestions for System Improvement by enquiry
committee of BPL division W.C. Rly:
{Ref.- CSTE/W.C. Rly. /JBP letter no. WCR/N-HQ/110/ET/RRI dated 31.03.2016}

There should not be any false ceiling in the Relay Room and Panel Room. The height
of roof slab should be decided according to cooling requirement. Accordingly, false
ceiling wherever available in the Relay Room and Panel Room should be removed
and the same should not be provided in future installation.
Fig 46: False ceiling

Standby operating panel should be kept ready for movement on at least Two lines in
case of such emergencies. (dealt by RDSO).
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Handbook on Safety in Signalling 2.0
Fig 47: Operating Panel

Provision of CCTV camera at appropriate location inside Relay Room – configuration
of which depends upon no. of cameras, visibility at night, storage capacity of the
system.
Fig 48: CCTV camera installation


4.1.2
Fire alarm may be linked with power shut down arrangement so that as soon as alarm
activates, simultaneously power also shuts down.
Inside Relay Rooms other than relay rack, nothing should be kept there preferably,
but if inevitable then steel materials only should be used like steel table, records in
steel almirah etc. Example of unwanted material – loose wire pieces, released material
etc.
Precautions to Prevent Fire Incidences at S&T installations:
{Ref.- Pamphlet on Fire Protection & safety at RRI Installations by S&T/CAMTECH,
Gwalior}




The firefighting equipment should be placed at such locations from where equipment
is clearly visible and easily approachable from working place.
At stations where Fire Alarm System has been provided, should be tested Once in a
Week.
Fire extinguisher equipment to be made available at all the places as per requirement
and their refilling to be ensured.
At stations, with shift duty staff, Relay Room to be opened in each shift and a visual
inspection of complete Relay Room to be done. (Where it is not possible to open the
Relay Room frequently as above, a visual inspection through glass door or window
can be done from outside). At other stations/RRI installations with no shift duty staff,
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Handbook on Safety in Signalling 2.0


the above inspection to be done Once in a Day. At all the other stations the above
inspection to be carried out at least Once in a Week.
A record of such inspections to be kept. A register to be opened with
SSE/Sig/Control, in which position of all junctions and RRI stations to be recorded
per day.
A joint inspection with Electrical department to be done which conforms to
previously issued JPO.
4.2
Precautions/Recommendations for RRI installations:
4.2.1
First Aid Box:
{Ref.- Pamphlet on Fire Protection & safety at RRI Installations by S&T/CAMTECH,
Gwalior}

Ensure availability of First aid box in duty room.
Fig 49: First Aid Box
4.2.2
Provisions in RRI Building Before Commissioning:








4.2.3
Window air-conditioners installed in Relay Room are causes of failure of power
supply during summer. Excessive load in summer due to continuous use may lead to
fire in Relay Room. Centralized cooling of Relay Room is recommended in place of
window air conditioners.
The entry of outdoor Signalling & Telecom cables in the building should be in a fully
secured manner.
There should be a provision of cable pit at the entry point outside the building/cabin
in which the coils of outdoor cables to be buried with sand.
A small pond filled with water nearby should be constructed near the cable pit. Apart
from emergencies like fire incidences, the water from the pond can be used in AC
plant also in routine working.
Provision of openings in the wall for cable entry from one room to another should be
done. The tendency of breaking wall or roof for cable entry or any other purpose after
commissioning should be discouraged.
There should be provision of permanent duct for cables on each floor of the building.
Electrical layout plan and new cables should be got approved by electrical
department.
From the past experiences, false ceilings are prone to catch fire therefore no false
ceiling should be provided in the Relay Room or panel room.
Wiring and Cabling:


Signalling Cables & Signalling Power Cables should not run in same path. They
should be laid in separate channels or ducts.
Colour coding of wires as per zonal railway instructions should be strictly followed
for easy identification of different types of power supplies such as 60 V DC, 24V DC,
110 V AC etc. as well as positive and negative paths such as B60, N60, BX110 and
NX110 etc.
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Handbook on Safety in Signalling 2.0



4.2.4
All electrical department cables and S&T cable should also run in different paths.
Where a wiring system passes through elements of building construction such as
floors, walls, roofs, ceilings, partitions or cavity barriers, the openings remaining after
passage of the wiring system shall be sealed according to the degree of fire resistance
required of the element concerned, if any.
Except for fire resistance over one hour, this requirement is satisfied if the sealing of
the wiring system concerned has been type tested by the method specified in the
relevant Indian standard. Each sealing arrangement used shall comply with the
following requirements:
a) It shall be compatible with the material of the wiring system with which it is in
contact.
b) It shall permit thermal movement of the wiring system without reduction of the
sealing quality.
c) It shall be removable without damage to existing cable where space permits
future extension to be made.
d) It shall resist relevant external influences to the same degree as the wiring
system with which it is used.
e) Fire alarm and emergency lighting circuits shall be segregated from all other
cables and from each other.
Fire Extinguishers:


Adequate number of firefighting equipment should be available inside Squeeze grip
Relay Room, Power equipment room, Battery room and
Operating Panel room or as per zonal railway instructions at
such locations from where equipment is clearly visible and
easily approachable from working place.
Always use the correct type of fire extinguisher. Only Carbon
dioxide (CO2) type fire extinguishers to be used in S&T
installations which are suitable for liquid and
Discharge nozzle
electrical fire.
Fig 50: Fire Extinguisher
4.2.4.1 Caution:


DO NOT use CO2 type fire extinguishers on metal fires.
Keep your hands away from the plastic discharge nozzle, which gets extremely cold
during operation.
4.2.4.2 Inspection of CO2 type Fire Extinguisher:





Make sure the extinguisher is mounted in a location where it is visible and easy to
locate during an emergency.
Check the tamper-seal to verify it is not broken or missing.
Ensure the pull-pin is not missing.
Check the extinguisher for obvious physical damage, corrosion, leakage, or a clogged
nozzle, and report if any to the concerned agency.
Ensure that the extinguisher is not over due for recharging.
Note: Carbon Dioxide extinguishers do not have a gauge. The only method for verifying a
carbon dioxide extinguisher is fully-charged is to weigh the unit and verify with the weight
written on the equipment.
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Handbook on Safety in Signalling 2.0
4.2.5
Smoke Detectors:
If the smoke detector gets filled with dust, it will not be able to sense the smoke and
work properly in an emergency.
Cleaning smoke detector is the best way to make sure smoke
detector is capable of alerting when a fire occurs. Hence smoke
detectors should be cleaned at least Once in every Six Months or
as per the manufacturer’s instructions.
Remove the face of the unit and then use a commercial vacuum
cleaner with a brush attachment to gently brush and vacuum the
inside of smoke detector and an air pressure canister to blow
Fig 51: Smoke Detectors
through the smoke entry points.
4.2.6
4.2.6
Fire Alarm System:

Periodically check the effectiveness of fire alarm system and smoke detectors if
provided Signal Maintainer – Every Week
 JEs -Once in a Month
 SSEs- Once in a Quarter
Or as per Zonal Railway’s instructions
Counselling:
S&T and Operating staff should be counselled regarding fire prevention, and working of
Fire Alarm System and operation of fire extinguishers.
4.2.7
Circuit alteration:


During any circuit alteration work it should be ensured that the
new signalling wires do not run over electrical department
wiring.
Loose wiring or connection is one of the causes of fire hence no
wire should be left open, loose or hanging. All the wiring should
be properly routed, bunched and laced.
Fig 52: Loose wires
4.2.8
Joint inspection with Electrical department:
A joint inspection with the officials of electrical department should be done quarterly in
which deficiencies if any to be noted their rectification to be ensured at the earliest.
4.2.9
Storage of material:
Always keep sufficient space between stacks of material placed inside store room so that
if one stack catches fire it can be quickly extinguished and cannot spread to other stacks.
4.3
4.3.1
Do’s and Don’ts:
Do’s:





Use ISI marked or Quality Control certified electrical material and appliances.
Use Earth Leakage Circuit Breakers (ELCBs) to avoid accidents from earth leakage
current.
Use good quality fuses, miniature circuit breakers and earth leakage circuit breakers
of correct ratings.
Use one socket for one appliance.
Switch off the electric supply of fire affected areas.
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Handbook on Safety in Signalling 2.0














4.3.2
Use dry chemical powder type extinguishers on electric fires.
Fuses and switches should be mounted on metallic cubicles for greater safety against
fire.
Replace broken plugs and switches immediately.
Keep the electrical wires away from hot and wet surfaces.
Switch off appliances after use and remove plugs from the socket.
Switch off the Main switch when leaving the premises, home for a long duration.
Use electrical wires, cables and materials of proper capacity and insulation.
The relevant Code of practice for prevention of fire should be followed.
Ensure easy access to put off the supply.
Use switches which clearly indicate “ON” & “OFF”.
Crimping should be done with the proper size/ type of cable lug & terminal or ferrule
with the use of proper crimping tool.
Keep the electrical switch room neat, clean and ventilated.
Use insulated wire for neutral and independent wire for earthing.
Check sockets/plugs/wirings thoroughly if any overheating marks are seen.
Don’ts:

















Don’t use substandard fixtures, appliances.
Never have temporary or naked joints on wiring.
Don’t lay wires under carpets, mats or doorways. They get crushed, resulting in short
circuiting.
Don’t allow appliances cords to swing.
Don’t place bare wire ends in a socket, use a three pin plug top.
Do not remove plugs by pulling the wires.
Do not smoke in electrical zone.
Do not connect fuse in the neutral circuits.
Do not replace fuse unless fault is detected.
Do not plug in lamp or appliance with the switch ON.
Do not overload any electrical circuit.
Do not use water to extinguish electric fires.
Do not construct any house or structure below the overhead electric lines and
maintain the specified horizontal distance from the lines.
Do not use wires and cables with joints.
Do not dry clothes like tea towels etc. over the electrical heater, cooking pan etc.
Do not leave ovens in “ON” condition after use.
Do not sit too close to the heater to keep warm. You could easily set fire to your
clothes or your chair, particularly if you fall asleep.
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Handbook on Safety in Signalling 2.0
Section-5
Additional Safety Precautions for Signalling in RE Area
49
Handbook on Safety in Signalling 2.0
5.1
Laying of Signalling Cables in RE Area:
{Ref: Para 15.3.1 of New SEM (July-2021)}
Only unscreened approved type underground cables shall be used for signalling
purposes. The following precautions shall be taken:






5.2
The cable shall be so laid that it is not less than one meter from the nearest edge of the
mast supporting the catenary or any other live conductor, provided the depth of the
cable does not exceed 0.5 m. When the cable is laid at a depth greater than 0.5 m, a
minimum distance of 3 m between the cable and the nearest edge of the O.H.E
structure shall be maintained. If it is difficult to maintain these distances, the cable
shall be laid in DWC-HDPE/Concrete Ducts or any other approved means for a
distance of 3 m on either side of the Mast. When so laid, the distance between the
cable and the mast may be reduced to 0.5 m. These precautions are necessary to avoid
damage to the cable in the event of the failure of an overhead insulator.
In the vicinity of traction sub stations and feeding posts, the cable shall be at least one
metre away from any metallic part of the O.H.E and other equipment at the
substation, which is fixed on the ground, and at least one metre away from the
substation earthing. As far as possible, the cable shall be laid on the side of the track
opposite to the feeding post. In addition, the cable shall be laid in concrete or DWCHDPE pipes (approved type)/Split RCC pipes or other approved means for a length of
300 m on either side of the feeding point.
In the vicinity of the switching stations, the cable shall be laid at least One metre
away from any metallic body of the station, which is fixed in the ground, and at least
5 m away from the station Earthing. The distance of 5 m may be reduced to One
metre provided the cables are laid in Concrete Pipes/DWC-HDPE-Pipes of approve
type/ducts or any other approved means.
Where an independent Earth is provided for an O.H.E structure, i.e. where the mast is
connected to a separate Earth instead of being connected to the rail, the cables shall be
laid at least One m away from the Earth.
Where there are O.H.E structures along the cable route, the cable trenches shall as far
as possible, be dug not less than 5.5 m away from the centre of the nearest Track.
The use of G.I pipes or any form of metallic pipes is prohibited within a distance of
300 m from feeding post. Similarly, galvanized iron metallic pipes are prohibited in
close proximity to switching station earth or traction mast. {Para 20706 (vi) of
ACTM}
Electrical & Signal Clearance:
{Ref: Pamphlet on “Signalling in 25 KV AC Electrified Area” by S&T/CAMTECH,
Gwalior}
As per AC Traction Manual, the minimum vertical clearance between any live part of
OHE or Pantograph and part of any fixed structure (earths or others) or moving load
should be 320 mm to safeguard against flashing/arcing. This is termed as
Flashing/Arching Zone. Signal clearance diagrams are prepared in which an un-shaded
portion is marked indicating the flashing/arching zone. Under no circumstances, a signal
post or any of its fittings must be allowed to infringe in the un-shaded portion.
Under normal conditions, no one is allowed to approach closer than 2 m from the
extreme positions of the live parts of the OHE. This is marked as the shaded portion in
the signal clearance diagrams shown below.
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Handbook on Safety in Signalling 2.0
Where a signal post or its fittings have to be located
within 2 m of live OHE, a screen of wire mesh of
approved design solidly connected with the structural
work shall be provided between the signal post and
the OHE for protection of staff.
The staff is required to work with extra precautions
while working on such signals. If any part of their
equipment or tools is likely to come within 2 m of live
OHE, they will arrange for a power block before
taking the work on hand.
If the signal is:
a) Located above the contact wire and
b) Provided with the iron screen it is necessary to
connect them to the earth with earth resistance not
exceeding 10 Ω.
The screen shall be provided on the side adjacent to
the catenary.
For a signal post between two wired tracks, a screen on
either side of the post will be required.
5.2.1
Fig 53: Electrical Clearance for Signals
in RE Area
Clearances for Safety:
{Ref.: Para 22.2.6 of New SEM (July-2021)}
In the matter of electrical clearances, the fundamental rule to be observed is that no one
is allowed, under normal conditions, to approach closer than 2 meters from the extreme
positions of the live parts of the O.H.E. The following protective measures shall,
therefore, be adopted.
a) If any portion of a signal post or its fittings where signalling staff have to work, falls
within 2 meters of a 25 KV live conductor, or any metal part electrically connected
to this conductor such portion shall as far as practicable be protected by an iron
screening of approved design solidly connected to the structural work.
b) If for any reason it is not practicable to provide the protective iron screening as
mentioned above, a Caution Board of approved design shall be provided on the
signal post at a height of 3 meters above the rail level, to caution the signal staff.
Note: Technical personnel shall exercise particular care to protect themselves while working on
signal posts not provided with protective screens. If there is any likelihood of any part of their tools or
equipment coming within 2 meter of live equipment, they shall take a power block as detailed in
Chapter VI of the Manual of AC Traction-Volume II (Part-I). The same precautions are also required
in the vicinity of return conductors, which should be treated as live.
5.3
DC Track Circuits in RE Area:
{Ref: Pamphlet on “Signalling in 25 KV AC Electrified Area” by S&T/CAMTECH,
Gwalior}
In an AC electrified section one of the following track Detections to be used:  DC Single Rail Track Circuits
 AFTC
 Axle Counters.
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Handbook on Safety in Signalling 2.0
5.3.1
Modification to track circuits:
The parameters of track also changed with the increase of catenary current. But the same
AC immunized QTA2 & QBAT Track relays can be used with an additional choke at the
relay end & cross bonding with the negative rails of adjacent track. With QTA2 relays
with the above arrangements the length of TC can be up to 450 m. For QBAT relays with
8.8V battery, the length of TC can be up to 750 m. QSPA1 Relays are to be provided as
first repeater of TR.
In RE area, all parts are similar to that of Non-RE track circuit, except choke & Relay.
5.3.2
Feed End:
When shelf type ACI track relay is used, track feeding shall not be
done directly from a rectifier, without a battery in parallel. Also their
connection shall be so done that whenever battery gets disconnected,
rectifier also shall automatically be isolated from the track.
A ‘B’ Type choke connected in series with track feed to the uninsulated rail (-Ve Rail). This prevents damage to the feed source in
case of a catenary snap resulting in heavy currents in the un-insulated
rail. This is used for the safety of track circuit. This prevents damage
to the feed source at the time of a catenary snap resulting in heavy
currents in un-insulated rail. The "B' type choke shall conform to
specification no.IRS S 65 – 83.
5.3.3
Fig 54: ‘B’ Type Choke
Relay End:
Only A.C.I Track relays of 9 Ω - Shelf type/ QTA 2/ QBAT type shall be used. QTA2
(With ACI= 50 V) and Shelf Type relays (With ACI= 50 V)
are used for Track lengths up to 450 m beyond which up to
750m QBAT (with 80 V ACI) is used.
QSPA1 relay only shall be used (to add slight delay of 540 to
600 m secs) as repeater for QTA2 or QBAT track relay.
However, for ACI shelf type track relay, any AC immunized
line relay can be used as repeater due to its greater operate
time lag Compensate the OHE tripping effect on track circuit.
B type choke shall be connected in series with the relay also
for its protection to enhance the AC immunity of the track
relay.
Fig 55: Relay
In the case of shelf type ACI track relay with this choke in series, 450 m long track
circuit can be worked even with traction return current up to 1000 Amps. Without this
choke, 450 m long track circuit can be worked only when the traction return current is
within 600 Amps.
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Handbook on Safety in Signalling 2.0
Fig 56: Layout of A Typical Single Rail DC Track Circuit
Components:
1. Battery charger 110V /2-10V D.C
2. Feed Battery (1 to 4 secondary cells3)
3. Fuse & link (4A / 250V).
4. Regulating Resistance (adjustable 0-30 Ω)
5. Type 'B' choke (R=3 Ω & Z= 120 at 50 Hz).
6. Track lead cable (2 X 2.5 Sq. mm copper).
5.3.4
7. Track lead J.B
8. Track lead steel wire ropes
9. Transverse bonds
10. Block joints.
11. Track Relay (ACI).
12. Continuity Bonds.
RE Bonding:
In RE section, the traction returns current flows through rails. Hence, to allow traction
return current, DC single rail TC are provided. In a DC single rail TC, only one rail is
used for traction return current and the other Rail is insulated to work the track circuit.
The rail which is reserved for traction return current is called un insulated rail. Track
bonding is provided within un insulated rail.
 To provide a path for traction return current.
 To ensure proper functioning of protective equipment.
 To minimize damage to installation due to traction short circuit.
Type of RE bond:
1) Transverse bond
3) Cross bond
5.4
2) Longitudinal bond
4) Structural bond
Block Signalling in RE Area:
{Ref: Pamphlet on “Signalling in 25 KV AC Electrified Area” by S&T/CAMTECH,
Gwalior}
5.4.1
Type of Block Instruments Permitted in 25 KV RE:
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Handbook on Safety in Signalling 2.0
5.4.1.1 Single line sections:
a) Neale's Type token instrument
b) FM Type Token less block instrument
c) Block Working with Axle Counter
Fig 57: Neale's Type token instrument
Fig 58: FM Type token less block
instrument
5.4.1.2 Double line sections:
a) SGE type Double Line Block Instrument
b) Block Working with Axle Counter
Fig 59: SGE Type Double Line block
instrument
5.4.2
Special Arrangements for Block Circuits in 25KV RE:







All line circuits of Block working are transferred from OH transmission to
underground quad cables.
Each pair of quad is provided with an isolation transformer at either end.
Through the transformer the quad pairs are connected to block bell & block telephone
circuits.
To economies the number of line conductors the DC line circuits of Block instrument
are connected to the phantoms of the quad pair.
For Double line block instruments, the earth return line circuit is retained.
Block filter units are connected to the block line circuit wires at either end of section
to minimize the effect of AC induced voltage.
In place of quad cable, OFC, Radio & other communication means may also be used
for block circuits.
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Handbook on Safety in Signalling 2.0



In this case Failsafe block interface (FSBI) of approved design shall be used.
If the distance between FSBI & Block instrument is more than 500mt then, block
filter shall be provided in cable pairs connecting them.
When a block section originates at a station in electrified area and terminates at a
station in non-electrified area, filters shall be provided at both ends of such block
section.
5.5
Feeding of Power to Signals in RE Area:
5.5.1
Direct feeding of signals:
{Ref.: Section 6, Chapter-22 of New SEM (July-2021)}


The distance between the signal control relays and the signal must not exceed the
prescribed limits in electrified zone, measured along the line of way. This will ensure
that the voltage induced in the circuit will be inadequate to illuminate the lamps, even
under the most adverse circumstances and with one or more earth faults present.
Maximum permitted length of direct feed of signal shall be as per Table given below:
Table 3: Maximum permitted length of 110 V Feed System
Type of Cable
Unscreened

110 Volts feed system
Single Track
Double Track
180 m
220 m
For signals beyond the above distances Two methods are followed for feeding:
5.5.1.1 Local Feed Method:







The controlling relays HR, DR, HHR etc. in Relay Room are repeated through AC
immunized relays at the location.
The signals are locally fed from these relay contacts.
The length of parallelism of repeater relay circuits shall not be more than 3.5 Km.
Double cutting arrangement must be ensured by proving controlling Relay contacts in
both paths (BX110, NX110 & B24, N24).
No earth return circuit is permitted on any of the signal circuits as a single earth fault
may affect the characteristics of the relays.
Possibility of theft of equipment at Location.
More chances for manipulation of signals at Location.
5.5.1.2 Remote Feed Method:







It is an extension of direct feed method with certain additional protective measures.
The signals are directly fed from the cabin.
But in the signal lamp circuit, the OFF aspect controlling repeat relays are proved in
series.
ECR relays are kept at cabin only.
Only repeating relays of OFF aspect relays are to be provided in location.
Less requirement of cable conductors as additional power cable for carrying 110V AC
to location is not required.
Less chances for manipulation of signals at location.
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Handbook on Safety in Signalling 2.0
5.6
Electric Operation of Point in RE Area:
{Ref.: Section 7, Chapter-22 of New SEM (July-2021)}


Point detection and point detection repeat circuits shall use ac-immunized relay.
The maximum permissible length for various types of commonly used Point Machines is
as under:
Table 4: Maximum permissible length for Point Machines
Type of
Machine
As per
IRS S-24
AC immunity
level in volts
Maximum permissible parallelism in
meters between Point Contactor and Point
Motor
Single line
Double line
160
910
1100
400
2200
2800
Factor of safety is 1.5

5.7
Relays to be used in RE:








5.8
3 phase point machine is inherently immune to induced voltage and therefore can be
used for operating point to any length subject to its own operating limitation.
Shelf type Relays manufactured in accordance to BSS 1659 and RE Specification No.
187/11 and Plug in Relays QNA1 type are inherently immunized for 300 A.C. and so
can be safely used for a parallelism of 3.5 Km of
Screened Cables.
Polarized Relays using permanent magnets shall not be
used in any external circuit.
No rectifier shall be included in any external circuit of
Relays.
AC immunized Relays are only used for external
circuits.
Separate set of Battery/Power source shall be used for
internal & external circuits.
Fig 61: Relays
All circuits must be double cutting in external circuits.
EKT shall be operated through a line relay.
No earth return circuit is allowed except for block circuit for which special
arrangement is made.
Insulation of Rod & Wires:



Each rod or wire shall be provided with an insulator in the
lead out as close to the cabin as possible.
In case there is a large number of rodding in the same
alignment, the insulated joints shall be provided on each rod
run between the same sets of rod roller guides. If this is not
done any voltage appearing in one rod will be transmitted to
another rod through the rod roller guide.
For rod running under the track, the top of the rod shall
Fig 62: Rods with Insulator
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Handbook on Safety in Signalling 2.0


5.9
not be less than 25 mm below the bottom of the rail in order to ensure that the rails do
not come in contact with the rod during the passage of the trains.
Additional insulators shall be provided on each rod at every 300 m.
A minimum distance of 40 mm shall be maintained between the wire and nearest edge
of the rail or mast.
Laying of Signalling Cables:
As per extant instructions, only PVC insulated PVC sheathed and armoured unscreened
cable confirm to Specification IRS S-63-2007 shall be used for carrying signalling
circuits. To ensure safe working, all the aspects of cable laying process are under taken
following some principles:
a) Depth of cable trench
b) Distance from OHE Mast
c) Cable laying in the vicinity of TSS
d) Distance from FP, SP & SSP
e) Laying multiple types of cables
f) Cables crossing the Track
g) Cables across Bridges & Tunnels
h) Cable laying outside Station Limits
i) Cable laying within Station Limits
j) Precautions During excavation
k) The Cable Markers
Fig 63: Laying of signalling cables
l) Supervision of cable laying
5.10
Earthing Arrangements in RE Area:
Any dangerous voltage appearing on the exposed parts with respect to earth or due to
electromagnetic or electrostatic induction, are led to Earth protecting the staff against
electrical shock. To ensure reliable and safe operation of the equipment by limiting or
eliminating the induced voltages in signal and Block circuits the following Installations
to be earthed:
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
k)
l)
Lever frames and other metallic structures of cabin
LC gate winch, lifting barriers
Armour of signalling cables at either ends
Location boxes
Block circuits working on earth return
Surge arresters
Screens provided on signal posts < 2m from OHE live wire
Equipments like EI, Axle counters, IPS, Data logger etc.
Signal posts, Panel, Relay/CT racks
Battery chargers
DG sets
All telecom equipments
The max permissible earth resistance has been specified as:
a) 10 Ω for Earthing of Lightning dischargers
b) 10 Ω for Signalling Equipments and
c) 1 Ω for Axle Counter Cables (Maintenance free earth)
In addition, latest EI equipments IPS & Digital Axle Counters are provided with special
earthing arrangements (Maintenance free earth) to obtain reliable earthing with earth
resistance of ˂ 1 Ω.
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Handbook on Safety in Signalling 2.0
5.11
Outdoor Signalling Circuits in RE Area:
{Ref.: Para 22.5.1 of New SEM (July-2021)}
5.11.1 Maximum Length of Parallelism:




The length of any signalling line circuit must be limited to ensure that the induced
voltage from the traction system does not exceed 400 Volts under normal conditions.
If necessary, line circuits must be sectionalized. Where line circuits leave line side
enclosures or buildings in different directions, this could give rise to a continuous
circuit of such length that the limits of induced voltage above could be exceeded. In
such cases a sectionalized power supply unit should be provided for each direction.
The induced voltage in the Underground-Unscreened cable shall be reckoned as 116
Volts/km on single line and 95 Volts/km on Double Line under normal conditions
when the catenary current of 800 amperes for single line and 1000 amperes for double
line.
When such circuits are terminated on relays/equipment their immunity shall not be
less than 400 V AC. Length of feed cable terminated on relay shall be suitably
reduced depending upon its AC immunity.
The length of DC Circuits on Line Relays with unscreened cable shall be restricted to:
Table 5: Length of DC Circuits on Line Relays with unscreened cable
Maximum permissible length on*
AC immunity level in
volts
Single Line
Double Line
QNA1/QNNA1/QNA1K
1000
2.1 km
2.8 km
K50 B1
170
1.0 km
1.2 km
K50 B1-A2
450
2.1 km
2.8 km
K50
130
750 meters
900 meters
AC Immunized neutral
relay (IHC Make)
750
2.1 km
2.8 km
Type of Relay
* Maximum permissible induced voltage is restricted to 400 V for human safety and factor of safety
1.5 has been considered.
5.12
Protection for Staff in 25 KV RE Area:
{Ref.: Para 22.8 of New SEM (July-2021)}
Railway personnel working on Signal & Telecommunication equipment on sections
provided with 25 KV A.C traction are required to take suitable precautions on account of
the following: a) Proximity to live conductors.
b) Presence of returns currents in the rails.
c) Induction in all metallic bodies situated near the overhead equipment.
5.12.1 Safety Precaution against proximity of a Live Conductor:
Any contact direct or indirect, with the 25 KV conductors is dangerous and shall be
strictly avoided.
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Handbook on Safety in Signalling 2.0
5.12.2 Safety Precautions against Presence of Return Current in Rail:
 The flow of return current in the rails will give rise to a potential difference.
a) Between adjacent rails at an insulated joint of a track circuit or at an ordinary joint in
case the fish plates and bonding are broken.
b) Between the ends of a fractured rail at the fracture.
c) Between an insulated rail and the non-insulated rail used for the traction return
current.
d) Between the rail and the surrounding mass of earth.

Wherever staff has to work on installations, which are in direct or indirect contact
with the rails, they shall:
a) Use Insulated tools in accordance with approved instructions.
b) Observe provisions of Maintenance of Track in Electrified Areas (Given at
Annexure-B).
5.12.3 Safety Precautions against induction in Metallic Bodies Situated Close to
OHE:
When staff have to work on Signal and Telecommunication Circuits on 25 KV AC
electrified lines, they shall take the following precautionary measures:
a) They shall as a general rule, wear rubber gloves and use tools with insulated handles.
b) When the work to be done is of such a nature that rubber gloves cannot be used
conveniently, special precautions shall be taken by splitting the circuits into sections
or earthing them. In special cases, both the steps shall be taken simultaneously. If
these protective measures cannot be applied, staff must insulate themselves from the
ground by using rubber mats, etc.
c) The cable conductors pertaining to the block instruments are likely to develop heavy
induced voltages and every time the staff handles the terminals of Block Circuits,
they must rigidly observe the provisions of paragraphs (a) and (b) above. These
cable terminals shall be printed “RED” to remind the Maintenance staff of the
danger. The Maintenance SSE/JE (Signal) shall explain the meaning of this painting
to the maintenance staff and ensure that they correctly understand it.
5.12.4 Safety Precautions for working on S&T Cables:
Before any work is undertaken on Signalling/Telecommunication cables, the staff shall
take the following precautionary measures:
a) Reduce the length of the circuit as much as possible.
b) Use Rubber gloves as far as possible or alternatively use insulated rubber mats.
c) Before cutting the armour or the metal sheath of the cable or the wires in the cables,
an electrical connection of low resistance shall be established between the two parts
of the armour, the Sheathing and wires that are to be separated by cutting.
5.12.5 Safety Precautions for working on Electrical Circuits:


Staff who have to work on electrical circuits shall be equipped with insulated tools
such as box spanners, pliers, screw-drivers, etc. They shall, in addition, be supplied
with rubber mats and rubber gloves. In regard to staff who have to work on equipment
directly connected to the rails, tools with insulated handles may be supplied as far as
possible and as far as practicable. A plastic sleeve on the handle will be sufficient in
most cases.
Staff shall make themselves familiar with the instructions for treatment of persons
suffering from electric shocks. Instruction Boards in English and in the regional
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Handbook on Safety in Signalling 2.0
languages describing the methods to be adopted for treatment of electric shock shall
be clearly displayed in all SSEs/JEs (Signal)' offices.
5.12.6 Safety Precautions for Breakage of Catenary/Contact Wire:
In the event of break of catenary/contact wire of the overhead electrical equipment, the
following precautions shall be taken for the safe working of the signalling equipment:
a) The Train Controller, on receipt of an advice of a break in Traction Overhead Lines or
confirmation of such an advice from the Traction Power Controller, shall immediately
advise by the quickest possible means, to all the staff responsible for the maintenance
and operation of the signalling equipment of the section where the catenary/contact
wire has broken.
b) The staff responsible for the operation of the Signalling equipment of the section shall
immediately check whether the block and other signalling equipment are working
normally. If an abnormal working of any equipment is noticed, its working shall be
immediately suspended and necessary action under the Rules shall be-taken.
c) On receipt of this intimation, the staff responsible for the maintenance of Signalling
system of the section shall immediately proceed to the site and test all circuits and
allied equipment paying particular attention to the external signalling gear to ensure
that no damage to it has taken place. An authorised representative of the Signal
Department not below the rank of SSE (Signal) shall submit Certificate that
everything is working all right and send it to his superiors along with a detailed test
report as soon as possible.
5.12.7 2.2 KV Charging as an Anti-Theft Measure:


Guidelines for anti-theft charging pertaining to S&T works as prescribed in Appendix
VII of ACTM Vol-II Part II shall be followed.
Besides, any specific works pertaining to specific section, the following S&T work
shall be completed before issue of certificate for 2.2 KV charging:
a) Replacement of existing DC track relays and DC line relays by AC immunized
relays.
b) Provisions of wire mesh screen on the working platform of existing signals in case
the requisite electrical working clearance of 2 meters is not available. No portion
of signal post or its fittings shall be less than 700 mm from the live conductor.
c) Supply of insulated tools to maintenance staff.
d) Conversions of all overhead track crossings of BSNL and Railway into cables and
removal of overhead wires thereof.
e) Certificate of clearance from DOT regarding 2.2 KV anti-theft energisation.
5.12.8 Checklist of works to be completed:
An approved checklist of the works to be completed as per provisions of this chapter
shall be issued by Principal Chief Signal and Telecom Engineer to the field offices.
Compliance of this checklist shall be insured by the nominated officers responsible for
issue of certificate before OHE is charged at 25 KV.
Note: Please refer to concerned chapters of SEM for specific requirements for any particular
Type of equipment.
5.12.9 Maintenance in Electrified Areas:
{Ref: Part-F of New IRPWM-2020}.
The safety measures for staff working in Electrified areas shall be given in Annexure-B.
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Handbook on Safety in Signalling 2.0
Section-6
Safety & Integrity Checks for Interlocking/Logic Circuits
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Handbook on Safety in Signalling 2.0
6.1
Interlocking Testing:
Interlocking test of a Signalling installation is carried out to check and confirm the
correctness of the wiring as per the approved circuit.
In case of PI & RRI, this is performed by testing integrity of wiring. This test can be
done by simulation panel at site. The Interlocking testing for a new installation is done
after completion of the wiring of circuits and before soldering of wires. During this
testing each and every route mentioned in the Route Control Table or Selection Table are
operated from the Control Panel. The relevant signals are taken off and the condition of
the passage of train over the signalled section is simulated. After which the routes get
cancelled automatically. The manual cancellation methods of routes are also required to
be tested like SM’s cancellation of route and individual sub-route cancellation by the
S&T staff to see that they respond correctly.
In case of EI, it is carried out by testing integrity of Application Logic (Software). It is
possible to carry out this test by using Simulator and Emulator at factory, drawing office
as well as the site as an offline activity. Interlocking Testing for EI is done in two stages:
a) Factory Acceptance Test (FAT)
b) Site Acceptance Test (SAT)
In a FAT Test, the simulation is done only for the interlocking software. FAT is to be
done for all major/minor yards for both new works/modifications in existing EI. FAT
should preferably be conducted at factory premises. However, FAT can also be done at
Railway premises at central location but not at site.
SAT is to be conducted thoroughly for all new installations.
Note:
i.
ii.
6.1.1
FAT should preferably be conducted at factory premises. However, FAT can also be
done at railway premises at central location but not at the site. For this, the setup should
be made by all the Zonal Railways.
FAT & SAT should be done by separate officials where ever feasible.
Factory Acceptance Test (FAT):


Factory Acceptance Test (FAT) for EI system shall be tested in Factory environment
with simulation setup to validate application software.
The purpose of Factory Acceptance Test is to:
a) Ensure that the Interlocking system fulfils the station Interlocking & Route
Control Chart requirements and workings in safe manner even if any false inputs /
information received.
b) Minimises the site errors & risks and reduces the corrections at site. This results
in saving of time at site testing.



FAT is carried out through simulation set up (using Simulator Panel with toggle
switches or Simulator PC with Interlocking Simulation Setup - software) in which all
field inputs are simulated.
FAT is carried out for each station interlocking installation separately.
After designing the Application Software, designer issues it to the validation
department for carrying the Factory Acceptance Test.
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Handbook on Safety in Signalling 2.0




It is carried out only through VDU panel, whereas Site Acceptance Test (SAT) is
carried out through CCIP and VDU panels, if both the options are available at site.
During FAT, Timers in Application logic are modified for the FAT testing for Timer
values used for signal, point, overlap and cancellation are reduced from 120 seconds
to 12 seconds to speed up the testing. It is essential that the original values of timers
are reinstated and validated at the completion of testing.
In FAT setup, the I/O boards are not physically present and the same are simulated
using the test setup. Therefore, field inputs and outputs delivered by Input and Output
card will be disabled and will be directly delivered into simulation VDU. However,
this will not affect the interlocking part of the application logic.
To carry out FAT, the following inputs are required:
a)
b)
c)
d)
e)

Signal Interlocking Plan (SIP)
Route Control Chart (RCC).
Control cum Indication Panel Diagram.
Cross Table/Square sheet.
Station Interlocking Application Software files as designed (example in case of
Microlok II, .ML2, MLL, MLP).
After carrying out FAT, the following are the outputs:
a) Station Interlocking Application Software files as tested (example in case of
Microlok II, ML2, MLL, MLP).
b) Total Management System (TMS) Forms.
c) FAT Certificate.
When Railways/Customer testing is completed, the Check sum and CRC values of the
FAT simulated application logic will be recorded as per the Application Logic and it is to
be jointly signed by OEM and Railways representative.
6.1.2
Site Acceptance Test (SAT):

Site Acceptance Test (SAT) defines the procedure for Site testing of Station
Interlocking System, where tests are executed at site environment.
 SAT mainly involves the System integrity and functional testing of all equipments
and interlocking testing also shall be carried out with full setup except the trackside
equipments.
 SAT is carried out for each station separately.
 Results of the tests are observed and documented in a Test Report.
 The Site Acceptance Test ensures that all the equipments installed at site i.e. EI
Hardware, Communication equipments, Power supply equipments, Relays and
Control Cum Indication Panel are functioning correctly as per approved system
configuration and station interlocking requirements and working in safe manner and
failsafe even if any equipment fails/false inputs/information received.
 SAT ensures the overall system safety and error free system is being delivered to the
client.
 To carry out SAT, the following inputs are required:
a) Application source file, Application listing file, Application program file (in
case of Microlok II, ML2, MLL &. MLP file (Hardcopy & Read-only
Softcopy)
b) Station SIP
c) Station Route control chart
d) Station Control cum indication panel diagram
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Handbook on Safety in Signalling 2.0
e) Square Sheets/Cross tables
f) Wiring Circuits



All the equipments involved for station working are being installed before proceeding
SAT, so there is no need of separate set up is required except to simulate the field
inputs with Simulation Panel.
All the field inputs are simulated by using simulation panel through toggle switches
and inputs are sent to EI via relays and the field outputs are sent to lamps through
relays.
The following testing shall be carried out while doing SAT:
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
k)
l)

Visual test
Wire count test
Bell test
Insulation resistance test
Earthing test
Power On
VCOR
Communication testing
Correspondence Test
System Integrity Test
Interlocking testing
Change over test
As explained above SAT is performed in two stages:
1. Testing of Electronic Interlocking at site with E.I. hardware and simulation panel.
2. Testing of the outdoor gears, viz., points, signals, track circuits, LC gates etc.
Following guidelines are to be followed during SAT:
{Ref.: Northern Railway Policy No.07/2018 dated 03.04.2018}





SAT for EI should be done first from panel and thereafter from VDU.
SAT certificate should be signed only after testing has been completed both from
panel and VDU.
If dual VDU is provided, then SAT to be done with each VDU separately.
SAT certificate should be jointly signed by OEM and Railways. SAT certificate
should mention Check-sum as well as CRC code of the final interlocking logic loaded
in EI on which station will be commissioned. This certificate should also mention the
changes made after the FAT.
Above tests may be under taken using data logger also.
6.1.2.1 Functional testing:

Functional Testing of a Signalling installation is carried out to confirm that the
various gears controlled from the interlocking correspond correctly to the operation of
the Control Panel. It is physical verification of correspondence of functioning of
actual gears and devices connected at site with PI/RRI/EI.
6.1.2.2 Periodical testing:

Periodical tests of signal interlocking installations are performed for a working
installation at specified periods.
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Handbook on Safety in Signalling 2.0
Periodicity of Tests (for Existing Installations – Relay Interlocking/
Electronic Interlocking):
6.2
{Ref: Para 21.6.1 of New SEM (July- 2021)}

In a working installation, the following periodical tests shall be done:
i. Physical inspection Once in a Year or earlier as feasible.
ii. System integrity test as per para 19.8.8 of SEM Once in Five Years or earlier if
interlocking is altered.
iii. Insulation tests on Cables as mentioned in Chapter 15 of SEM.
iv. Test of individual equipment in accordance with specifications and instructions
applicable for each apparatus as stipulated.


6.3
It will be personal responsibility of SSE/JE (Signal) to test all Electrical Signalling
Circuits of Relay Interlocking up to 20 routes.
It will be personal responsibility of ASTE/DSTE concerned to test all Electrical
Signalling Circuits of Relay Interlocking with more than 20 routes.
Interlocking / Logic Circuit Tests for EI:
(Ref.: Northern Railway Policy No.07/2018 dated 03.04.2018)

As per the existing practice, Testing of Electronic Interlocking is done with Selection
Table during FAT/SAT. There are number of tests which are also important and
should be done along with selection table test. The following Interlocking
Logic/Circuits tests and certifications given in Table below are to be completed for
each and every station before commissioning:
Table 6: List of interlocking /Logic Circuit Tests for EI
S. No.
1
2
3
4
5
6
7
Test Type
Description
Negative Test
Status of every function mentioned in STLT will be
changed i.e. track, point, LX gate, slot, crank handle etc.
controlling the signal and observe the change in the
status of the sign
One Signal One Train Test
After signal is cleared, first control track circuit is
dropped and picked up. Signal shall change to red and
remain in danger even after first control track circuit is
picked up again
Route release Test for light After clearing the signal, tracks are dropped to simulate
engine movement
light engine movement. Route release relays operation
as specified in STLT at each stage is checked
Route release Test for long train After clearing the signal, tracks are dropped to simulate
movement
long train movement. Route release relays operation as
specified in STLT at each stage is checked.
Route Holding Test
All route releasing conditions are fulfilled except the
picking up of route holding track and route locking is
observed
Approach Locking Test
Signal is cleared without approach track occupied.
Route release shall take place without time delay after
cancellation of route. With approach track occupied
cancellation shall take place with time delay.
Red Lamp Protection Test
When signal is cleared and red aspect of signal in ahead
becomes unavailable. Previous signal shall change to
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Handbook on Safety in Signalling 2.0
8
9
10
11
12
13
14
15
16
17
18
19
danger.
After signal clearance, each OFF aspect supply is cut
off. Signal shall change to more restrictive aspect.
Signal Aspect Sequence Control After clearing all signals for a line, each aspect of a
signal starting from advanced starter is brought down to
next restrictive aspect. Change of aspect of signals in
rear are observed as per STLT/Aspect Control Chart
Track Locking Test For Points
Each controlling track is dropped and attempt is made
for operating the point. It shall not operate. However,
emergency point operation shall be possible in this
situation.
Crank Handle Locking Test
Attempt is made to transfer the control of each crank
handle locked by the signal when the signal is cleared. It
is expected that the CH Control is not transferred. Test
should also be done to check releasing of CH when
point control is not available and/or TC is failed. It
should be possible.
LC Gate Locking Test
Attempt is made to transfer the control of each LC gate
locked by the signal when the signal is cleared. It is
expected that the Gate Control is not transferred
Route Locking Test
Attempt is made to operate each point which is locked
by the signal, when the signal is cleared. It is expected
that the point does not operate. Attempt is made to
operate each point which is not locked (Free) by the
signal, when the signal is cleared. It is expected that the
point Shall operate
SM Key Lock Test
Each Asset Operation is Tested for SM Key
Effectiveness
Point Operation Through Route All the controlling points in a route are set opposite to
Test
the required condition. Now route is initiated and
operation of Points to the required Position and setting
and locking of Route are checked.
Timers Test
All Timers are first set to their original value. After
setting a Route, Cancellation is applied and the time to
release of Route is observed. This test is repeated until
all the Timers are covered. Emergency operation of all
routes, overlaps, approach/ dead approach locking
should also be checked.
Square Sheet Test
A route is set and every other route is attempted to
check whether it is locked I free. This is repeated for all
the routes.
Route Checking Test
When all Non control Functions (Tracks, Points, Crank
Handles, Gates indications) are dropped. It is expected
that the Signal Status remains intact.
Correspondence of VDU & VDU and Panel indications at EI installations should be
Panel indications
checked. It should match.
Signal Lamp Cascading Test
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Handbook on Safety in Signalling 2.0
Back to LED Signal
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ANNEXURE-A: (Back to 2.1)
TVU->
Spl.
Class
>50000
A Class
B1 Class
B2 Class
C Class (Manned)
>30000
and
<50000
>25000
and
<30000
>20000
and
<25000
All other level crossings for road,
not covered in Special, A, B1 & B2
Classes
1. Interlocking of Gates with Signals
Should be Interlocked with Station Signals
a) Within
Station
Limits
b) Outside
Station
Limits
Should be Interlocked with Gate Signals
Should be Interlocked with Station
Signals in Suburban section, in
Automatic Block Signalling. In NonSuburban section, all traffic gates
should be interlocked with station
signal or if it has to be interlocked for
any other reason.
Other Stipulations
To minimize the Mean Waiting Time for road users, the
arrangement of Interlocking should be such that the last
operation before taking ‘OFF’ of Signal should be the
closing of the Gate and the first operation after the train
has cleared the Level Crossing and the Signal is put
back to ‘ON’ position, should be opening of the Gate by
the Gateman.
Should be Interlocked with Gate i) In case of Level Crossing protected by signal, where
Signals,
in
Automatic
Block the sighting of the signal by an engine driver is in
Signalling sections.
adequate and the Gate signal is not pre – warned
through other means (Distant Signal/Independent
Warner Signal/Repeater Signal etc.), a Warning Board
should be placed at not less than the emergency braking
distance in the rear of the Gate Stop Signal. The board
should be vertical 2000 mm by 450 mm with alternate
black and yellow strips 125 mm width painted on it at
an angle of 45 degrees. The top of the board should be 4
meter above rail level. The board need not be lit at night
but should as for as possible be provided with scotch lite
or other effective light reflectors or retro- reflective
tape.
ii) Where level crossing is situated outside station limits
but in close proximity thereof, the clear distance
between the level crossing and an outer signal should
not be less than the full train length.
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Handbook on Safety in Signalling 2.0
Note: All manned level crossing gates both within and outside station limits falling on suburban sections and
irrespective of the classification/TVUs of the gates.
Shall be normally kept open to Road Traffic
If Interlocked, shall be normally kept
c) Normal
open to Road Traffic
Position
of Gate
2. Telephonic or any other Approved type Communication from the Gate Lodge
Telephone or any other approved type be provided with ASM’s office with all Manned Level
Within or
Crossing Gates.
outside
Station
Limits
Ref. Railway Board letter no. 2010/Tele/11(11)/1 Pt. dated 31.10.17
Automatic Block Signalling section shall be interlocked
In Block Sections having large number of Level
Crossing Gates, the connections should be uniformly
distributed between the Block Stations.
3. Warning Bells or Hooters Operated by Approaching Train at Interlocked LC Gate
Provision of Warning bell or hooter operated by Approach Train at Interlocked LC Gates in suburban section and non-suburban sections be provided on
Within or
sections having Automatic Signalling. (Ref. RB’s letter No. 2011/SIG/WP/LC/IR/1 dated 20.02.2013)
Outside
Station
Limits
4. Type of Lifting Barrier
Electrically Operated Lifting barrier
Electrically Operated Lifting barrier In Non-Suburban Section, Electrically Operated Lifting
a) Within
in Sub-urban Section.
barrier be provided, where Power supply is Reliable.
or Outside
Station
Limits
5. Approach Locking
(i) To be provided in Sub-Urban Section.
(ii) Dead Approach Locking with Timing of 60 Sec in other sections.
6. Warning Bell or Hooter for Road User
Provision of Warning Bell or Hooter may be provided at all interlocked LC gates for road users which will sound during closing of gate.
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Handbook on Safety in Signalling 2.0
ANNEXURE-B: (Back to 5.12.2, 5.12.9)
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REFERENCES
1.
CAMTECH’s Publication “Handbook on Safety in Signalling” (Dec-2006).
2.
Indian Railway Signal Engineering Manual (IRSEM) version-3, July-2021
3.
Indian Railway P.Way Manual (IRPWM), June-2020.
4.
CAMTECH’s Publications “Maintenance Instructions on Relay Room
5.
CAMTECH’s Publications on “Do’s & Don’ts for Panel Interlocked Station”.
6.
https://chandramoleshwar.com/monsoon-precautions-for-signal-telecommunicationgears-indian-railways/.
7.
Installation Manual for LED Signal Lighting Unit as per RDSO/SPN/199/2010
(Rev.1.0) by M/s General Auto Electric Corporation Mumbai.
8.
Information brochure on LED Signals for Railway Signalling by M/s Efftronics
Systems Pvt. Ltd., Vijayawada.
9.
Pamphlet on “Fire Protection & safety at RRI Installations” by S&T/CAMTECH,
Gwalior.
10. Technical Advisory Note dated 04.06.2015 by Dir/Signal/RDSO, LKO.
11. CAMTECH's Handbook on Lead Acid Cell (March 2005)
12. CAMTECH's Pamphlet on VRLA battery (July 2007)
13. CAMTECH’s Publication “Handbook on study of Data logger reports”.
14. UM 6800C –Microlok II – Startup & Maintenance.
15. CSTE/W.C. Rly. /JBP letter no. WCR/N-HQ/110/ET/RRI dated 31.03.2016.
16. Pamphlet on “Fire Protection & safety at RRI Installations” by S&T/CAMTECH,
Gwalior.
17. Pamphlet on “Signalling in 25 KV AC Electrified Area” by S&T/CAMTECH, Gwalior
18. Northern Railway Policy No.07/2018 dated 03.04.2018.
19. JMV LPS Ltd.’s Presentation on “Protection of Sensitive S&T Equipment of Indian
Railways against Adverse Effects of Lightning and Surges.
77
गण
ु वत्ता नीतत
“आर. डी. एस. ओ. लखनऊ में हम सतत सुधार और ग्राहक मूलर्ाांकन प्राप्त
करने हे तु गण
ु वत्ता प्रबांध प्रणाललर्ों को आवधधक समीक्षा के माध्र्म से रे लों में
र्ात्री एवां माल र्ातार्ात की बढ़ती आवश्र्कताओां, माांग और अपेक्षाओां को पूरा
करने के ललए गण
ु वत्ता प्रबांध प्रणाली की व्र्वाहररक आवश्र्कताओां और अनवरत
सुधारों को पूरा करने के समपाण, गुणवत्ता उद्दे श्र्ों को ननधााररत करके
अनुसांधान, अलिकलपों और मानकों में उत्कृष्टता के माध्र्म से वैधाननक और
ननर्ामक अपेक्षाओां का अनुपालन करते हुए सुरक्षक्षत, आधनु नक और ककफ़ार्ती
रे ल प्रौद्र्ोधगकी ववकलसत करने हे तु सेवाओां को बनार्े रखने और अद्र्तन
पारदर्शी मानकों हे तु प्रनतबद्ध हैं। इसे सांगठन के अांदर सांसूधित एवां लागू ककर्ा
गर्ा है तथा सिी सम्बांधधत इच्छुक पक्षकारों को िी उपलब्ध करार्ा गर्ा है ।“
QUALITY POLICY
We at RDSO Lucknow are committed to maintain and update
transparent standards of services to develop safe, modern and cost
effective railway technology complying with statutory and regulatory
requirements, through excellence in research, designs and
standards by setting quality objectives, commitment to satisfy
applicable requirements and continual improvements of the quality
management system to cater to growing needs, demand and
expectations of passenger and freight traffic on the railways
through periodic review of quality management systems to achieve
continual
improvement
and
customer
appreciation.
It
is
communicated and applied within the organization and making it
available to all the relevant interested parties.
INDIAN RAILWAYS
Centre for Advanced Maintenance Technology
Maharajpur, Gwalior (M.P.), Pin Code – 474005