Railway Electrification: Signalling and Safety Requirements

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Questions and Answers

What may appear in Signalling and Telecommunication Circuits when situated close to the OHE?

Radio frequencies

Electromagnetic pulses

Induced voltage (correct)

Electrical currents

Why is it important to take precautionary measures when working on Signal and Telecommunication Circuits on 25 KV AC electrified lines?

To comply with electrified zone regulations

To reduce electromagnetic interference

To avoid electrical shocks (correct)

To prevent fire hazards

What should staff wear when working on Signal and Telecommunication Circuits to minimize the risk of electrical shock?

Insulated boots

Fire-resistant clothing

Safety goggles

Rubber gloves (correct)

What should be done to cable conductors pertaining to the block instruments to minimize the risk of electrical shock?

Splitting the circuits into sections Signup and view all the answers

Why should staff insulate themselves from the ground when working on Signal and Telecommunication Circuits?

To prevent electrical shock Signup and view all the answers

What is the purpose of printing 'RED' on the cable terminals?

To remind the maintenance staff of the danger Signup and view all the answers

Why is it important to take special precautions when working on equipment or circuits that are earthed?

To prevent electrical shock Signup and view all the answers

What should staff do when the work to be done is of such a nature that rubber gloves cannot be used conveniently?

Split the circuits into sections Signup and view all the answers

What is the primary reason for keeping sanded catch sidings not alive when an electric engine or multiple unit train is standing in the sanded track?

To protect staff from making contact between the permanent way formation and the electric engine or train Signup and view all the answers

Why is it necessary to keep the rails clear of sand for a length of 21.5 meters beyond the section insulators in the overhead lines?

To ensure proper electrical insulation of the section Signup and view all the answers

What is the primary concern related to metallic bodies situated close to O.H.E. in AC traction areas?

Induction of dangerous voltage due to proximity to traction conductors Signup and view all the answers

What is the primary purpose of keeping switches controlling the sanded catch sidings in the neutral position?

To prevent electrical shock or electrocution Signup and view all the answers

What is the primary reason for not allowing people to enter or leave the sanded catch sidings while the overhead equipment is alive?

To protect staff from making contact between the permanent way formation and the electric engine or train Signup and view all the answers

What is the primary concern related to sanded catch sidings in AC traction areas?

Electrical shock or electrocution due to poor electrical insulation Signup and view all the answers

What is the primary purpose of keeping the rails clear of sand for a length of 21.5 meters beyond the section insulators in the overhead lines?

To prevent electrical shock or electrocution due to poor electrical insulation Signup and view all the answers

What is the primary concern related to electrical safety in AC traction areas?

Electrical shock or electrocution due to poor electrical insulation Signup and view all the answers

What is the primary reason for using underground cables with a metal sheath in electrified areas?

To eliminate electrostatic induction Signup and view all the answers

What is a significant factor that affects the value of induced voltage in conductors parallel to the track?

Soil conductivity Signup and view all the answers

What is a crucial consideration when erecting signals in electrified areas?

Maintaining a minimum clearance from the live parts of the O.H.E. Signup and view all the answers

What type of signals are required to be used in electrified areas?

Colour light signals only Signup and view all the answers

What is a consequence of electromagnetic induction in conductors parallel to the track?

Development of currents and voltages in the conductors Signup and view all the answers

What is a key consideration when determining the location of signals in electrified areas?

Affording the best visibility to the Loco Pilots of approaching trains Signup and view all the answers

What is the purpose of the metal sheath in underground cables in electrified areas?

To eliminate electrostatic induction Signup and view all the answers

What is a factor that affects the potential differences between various points along the conductors and the adjacent Earth?

Return current through the rails and return conductor Signup and view all the answers

What type of tapes should be used in electrified tracks?

Linen tapes Signup and view all the answers

What should be kept clear of all materials in electrified structures?

The top of foundation blocks Signup and view all the answers

Why should temporary metallic jumpers be used during maintenance or renewal of track?

To maintain continuity of the rails serving electrified tracks Signup and view all the answers

What should be done to the two ends of a fractured rail during maintenance?

They should be temporarily connected by a temporary metallic jumper of approved design Signup and view all the answers

What should be used when touching the two parts of a rail in case of discontinuity of rails?

Gloves of approved quality Signup and view all the answers

What type of wagons should be used for material trains whenever possible?

Closed wagons Signup and view all the answers

Who should supervise the loading and unloading of open or hopper wagons in electrified tracks?

An Engineering official not below the rank of a Permanent Way Mistry Signup and view all the answers

What should be provided by the Electrical Department on requisition during maintenance or renewal of track?

A temporary metallic jumper Signup and view all the answers

What is the responsibility of every Engineering official working in electrical traction areas?

To possess a copy of rules framed for the operation of the Traction Power Distributions System Signup and view all the answers

What should be done when defects in overhead equipment are noticed?

Report to the Traction Power Controller and protect the line accordingly Signup and view all the answers

Why is it important to ensure that electrical equipment is made dead and earthed?

To prevent electrical shock to staff Signup and view all the answers

What is the path of the return current in electrified areas?

Fully through the rail Signup and view all the answers

Who is responsible for issuing written authority to commence work adjacent to electrical equipment?

A competent official of the Electrical Department Signup and view all the answers

What should be done when defects in overhead equipment are likely to cause damage to pantographs or trains?

Protect the line according to General Rule 3.62 Signup and view all the answers

What is the purpose of track and structure bonds?

To provide a path for the return current Signup and view all the answers

Why must electrical equipment be regarded as being 'live' at all times?

To prevent electrical shock to staff Signup and view all the answers

Why should staff ensure that the relative alignments of the centerline of the track with respect to the alignment of the contact wire are maintained within the specified tolerances?

To maintain horizontal and vertical clearances Signup and view all the answers

What is the reason for giving sufficient notice to traction staff when slewing or altering track involving adjustment of contact wire?

To adjust the overhead equipment accordingly Signup and view all the answers

Why is it essential to render the overhead equipment 'dead' during inspection of tunnel roofs and sides?

To inspect the tunnel roof and sides safely Signup and view all the answers

What is the reason for using special insulated apparatus when sounding unlined portions of tunnels to locate loose rock?

To prevent electrical shock Signup and view all the answers

Who should supervise the working of cranes in electrified areas?

Authorized overhead equipment staff Signup and view all the answers

What is the purpose of replacing bonds removed by the Engineering Department?

To ensure that the track is bonded Signup and view all the answers

Why should alterations to track involving adjustment of contact wire be carried out only in the presence of authorized staff?

To adjust the overhead equipment accordingly Signup and view all the answers

What should be done when defects in overhead equipment are likely to cause damage to pantographs or trains?

Report the defects to the Electrical Department Signup and view all the answers

What type of relays shall not be used in external circuits in 25 KV AC electrified areas?

Polarized Relays using permanent magnet Signup and view all the answers

What is the purpose of using separate batteries/DC-DC converters for external and internal circuits?

To ensure circuit isolation Signup and view all the answers

What should be done to wires pertaining to any individual circuit when more than one cable is laid between two locations or cabins?

Keep them in the same cable Signup and view all the answers

What is the purpose of making relays, which release an interlocking, slow acting?

To prevent releasing interlocking inadvertently due to voltage variations of short duration Signup and view all the answers

What type of wires shall be used for wiring in location boxes and cabins?

PVC insulated wires to an approved specification (IRS- S-76) Signup and view all the answers

What is the purpose of keeping batteries and wiring in equipment, location box or cabin well insulated from the ground?

To prevent electrical shock Signup and view all the answers

What is the time delay required for relays, which release an interlocking?

0.6 to 0.8 seconds Signup and view all the answers

Why are separate batteries/DC-DC converters provided for external and internal circuits?

To ensure circuit isolation and prevent electrical shock Signup and view all the answers

What is the minimum distance required before a signal for locating overhead equipment structures?

600 m Signup and view all the answers

What is the maximum allowed height above rail level for colour light signals without route indicators?

5.2 m Signup and view all the answers

What is the primary consideration when deciding the location of colour light signals with route indicators?

Availability of necessary minimum clearances Signup and view all the answers

When is it acceptable to locate drop arms of portals in the same lane as signals?

Only when there's no alternative Signup and view all the answers

What is the purpose of reducing the signal height in certain cases?

To ensure necessary clearances with overhead equipment Signup and view all the answers

What is the primary concern when locating colour light signals in electrified areas?

Minimum clearances with live wires and pantograph sway zones Signup and view all the answers

What is the purpose of offsetting the drop arms of portals from the centre line of the lane?

To ensure necessary clearances with overhead equipment Signup and view all the answers

What is the recommended action when it's not possible to locate overhead equipment structures at least 600 m before a signal?

Conduct a special study to determine the best solution Signup and view all the answers

What is the primary consideration for signal placement in electrified areas?

To maintain a safe distance from live conductors Signup and view all the answers

What is the purpose of wire mesh screens on working platforms of existing signals?

To ensure electrical working clearance of 2 meters is maintained Signup and view all the answers

What is the purpose of converting overhead track crossings of BSNL and Railway into cables?

To remove overhead wires and reduce electrical hazards Signup and view all the answers

What is the purpose of supplying insulated tools to maintenance staff?

To prevent electrical shock during maintenance Signup and view all the answers

Why is it necessary to maintain a clearance of 700 mm between signal posts and live conductors?

To prevent electrical shock and ensure safety Signup and view all the answers

What is the purpose of issuing a checklist of works to be completed before issuing a certificate for 2.2 KV charging?

To ensure compliance with S&T work Signup and view all the answers

What is the purpose of the certificate of clearance from DOT regarding 2.2 KV anti-theft energisation?

To prevent theft and ensure safety Signup and view all the answers

What is the purpose of replacing existing DC track relays and DC line relays with AC immunized relays?

To prevent electrical interference Signup and view all the answers

What is the primary reason for taking precautions while working in electrified sections?

To avoid direct contact with live O.H.E Signup and view all the answers

What is the minimum distance required from live parts of the O.H.E for work to be done without a 'permit-to-work'?

2 meters Signup and view all the answers

What is the purpose of ensuring that no part of a tree is nearer than a certain distance from the nearest live conductor?

To prevent the risk of electrical shock from trees Signup and view all the answers

Who is responsible for arranging to isolate and earth the section concerned and issuing a 'permit-to-work'?

Traction Power Controller Signup and view all the answers

What is the responsibility of every Engineering official working in electrical traction areas?

To take precautions to avoid electrical shock Signup and view all the answers

What is the purpose of track and structure bonds in electrified areas?

To connect steel structures such as foot-over bridges to rails Signup and view all the answers

What is the consequence of not taking precautions while working in electrified sections?

Direct contact with live O.H.E Signup and view all the answers

What is the role of the Engineering Inspector in relation to working adjacent to overhead equipment?

To apply to the proper authority for sanctioning the traffic and power block Signup and view all the answers

Study Notes

Catch Sidings

Normally, all catch sidings except those that are sanded shall be kept alive.
On sanded catch sidings, rails shall be kept clear of sand for a length of 21.5 meters beyond section insulators in the overhead lines.
Switches controlling sanded catch sidings shall be kept in the neutral position.

Precautions in AC Traction Area

In AC traction areas, additional precautions are required to be taken:
- Induction in metallic bodies situated close to OHE may cause dangerous voltage in metallic masses such as fencing posts.
- Signalling and Telecommunication Circuits may develop induced voltages due to parallelism to the track.
- Staff working on Signal and Telecommunication Circuits shall take precautionary measures:
  - Wear rubber gloves and use tools with insulated handles.
  - Take special precautions when work cannot be done conveniently with rubber gloves, by splitting circuits into sections or earthing them.
  - Insulate themselves from the ground using rubber mats, etc.

Signalling in Electrified Areas

Colour light signals only shall be used in electrified areas.
Signals shall be erected to maintain a minimum clearance from live parts of the O.H.E.
Instructions shall be strictly followed for electrical clearance.

Maintenance in Electrified Areas

Engineering staff shall be familiar with rules for operating the Traction Power Distribution System.
All electrical equipment, power lines, or cables shall be regarded as 'live' at all times.
Defects in overhead equipment shall be reported immediately to the Traction Power Controller.
Traction bonds: return current flows through the rail, and closed wagons shall be used for material trains.
Steel tapes or metallic tapes with woven metal reinforcement should not be used in electrified tracks; linen tapes are safer.
The top of foundation blocks in electrified structures should be kept clear of all materials.

Maintaining Continuity of Track

Continuity of rails serving electrified tracks shall be maintained during maintenance or renewal of track.
Temporary metallic jumpers of approved design shall be used to bridge gaps caused by removal of fish-plates or rails.
In case of rail fracture, temporary connections shall be made using approved design jumpers.
Gloves of approved quality shall be used to handle rail ends to avoid electric shock.

Safe Working Practices in Electrified Areas

Excavation work in electrified areas must be carried out in the presence of authorized staff from the Electrical Traction and S&T Departments.
The alignment of the centerline of the track must be maintained within specified tolerances with respect to the alignment of the contact wire.
Slewing or lifting of track must not be done outside agreed maintenance limits unless the position of the contact wire is altered at the same time.
Adjustments to cant have a magnified effect on the horizontal displacement of the centerline of the track with respect to the alignment of the contact wire.
Sufficient notice must be given to traction staff when adjusting contact wire to ensure overhead equipment is adjusted accordingly.

Alterations to Track Bonding

All bonds removed by Engineering Department staff must be replaced by Engineering Department staff and reported to the Assistant Electrical Engineer in charge.
Alterations to track bonding must be reported to the Assistant Electrical Engineer in charge without delay.

Working of Cranes

Cranes must only be worked with an authorized 'permit-to-work'.
Authorized overhead equipment staff must be present to ensure all safety precautions are taken.

Inspection of Tunnels

Overhead equipment must be rendered 'dead' for inspection of roofs and sides of tunnels.
Special insulated apparatus must be used for sounding unlined portions to locate loose rock in the roof and sides when the overhead equipment is 'live'.

Electrical Equipment

Batteries and wiring in equipment, location boxes, or cabins must be well-insulated from the ground.
PVC-insulated wires must be used for wiring in location boxes and cabins.
Separate batteries/DC-DC converters must be provided for external and internal circuits.
Polarized relays using permanent magnets must not be used in external circuits in 25 KV AC electrified areas.

Safety Precautions

Precautions must be taken due to the proximity of live conductors and the risk of direct contact with live O.H.E.
The return current in the rails may cause potential differences between rail and earth, between two ends of a fractured rail, between two rails at an insulated joint, and between earth and other metallic masses.
Work must not be done within a distance of two meters from live parts of the O.H.E without a 'permit-to-work'.

Colour Light Signals

No overhead equipment structure should be located in the same lane as signals for a distance of at least 600 m before a signal.
The Signal shall be mounted on an Offset Bracket if it is not possible to locate the signal outside the lane.
The principles mentioned above shall be observed for signals with route indicators.
Great care must be exercised in deciding the location of colour light signals with route indicators to ensure necessary minimum clearances are available.

Signalling in 25 KV AC Electrified Areas

Before issuing a certificate for 2.2 KV charging, specific S&T work must be completed, including the replacement of existing DC track relays and DC line relays by AC immunized relays.
An approved checklist of works to be completed as per provisions of this chapter shall be issued by the Principal Chief Signal and Telecom Engineer to field offices.

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Description

Learn about the signalling requirements in 25 KV AC electrified areas, including rules for catch sidings and safety precautions for electric engines and trains.