Signalling in 25KV AC Electrified Areas

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the first action a Train Controller should take upon receiving advice of a break in catenary/contact wire?

Immediately notify all staff responsible for signalling equipment (correct)

Check the functionality of the signalling equipment

Suspend all train operations in the section

Request help from other Train Controllers

If signalling equipment is found to be working abnormally after a catenary/contact wire break, what should be done next?

Continue operating the equipment until further notice

Inform the public about the issue

Immediately suspend its working and take necessary action (correct)

Attempt to fix the equipment on-site

What should be prioritized when staff arrive at the site of a broken catenary/contact wire?

Test all circuits and focus on internal signalling

Test all circuits and focus on external signalling gear (correct)

Upgrade the signalling equipment to avoid future breaks

Document the incident for future reference

What rank must an authorized representative possess to submit a Certificate regarding the functionality of the signalling system?

SSE (Signal) Signup and view all the answers

Which of the following is a guideline for anti-theft charging related to signalling and telecommunications (S&T) work?

Follow the guidelines prescribed in Appendix VII of ACTM Vol-II Part II Signup and view all the answers

What type of relays should be replaced as part of the 2.2 KV charging protocol?

Existing DC track relays and DC line relays with AC immunized relays Signup and view all the answers

What is the immediate responsibility of staff after confirmation of a catenary/contact wire break?

Check for normal operation of block and signalling equipment Signup and view all the answers

Which of these actions is NOT recommended after a break in catenary/contact wire?

Ignore the issue until the next scheduled inspection Signup and view all the answers

What is the normal height of the contact wire at supports for Broad Gauge?

5.60 meters Signup and view all the answers

In which locations are the diagrams for Broad Gauge not applicable?

Anchor spans Signup and view all the answers

What is the minimum height of the contact wire allowed in tunnels for Broad Gauge?

4.58 meters Signup and view all the answers

What protective measure should be adopted if a signal post falls within 2 meters of a live conductor?

Provide protective iron screening Signup and view all the answers

What is the normal height of the catenary at its highest point?

7.05 meters Signup and view all the answers

What is the fundamental rule regarding electrical clearances around live parts of the O.H.E?

No one can approach closer than 2 meters Signup and view all the answers

In case protective iron screening cannot be provided, what alternative is recommended?

Install a caution board at 3 meters height Signup and view all the answers

What factors do the clearance diagrams for wires accommodate?

Stagger and wind displacement Signup and view all the answers

What should staff working near the 25 KV conductors strictly avoid?

Contact with live conductors Signup and view all the answers

Which scenario is NOT a result of return current flow in the rails?

Fluctuation in track circuit readings Signup and view all the answers

What precaution must be taken when working on installations in contact with the rails?

Only insulated tools should be used Signup and view all the answers

What can cause induced voltage in signaling and telecommunication circuits?

Prolonged parallelism to the track Signup and view all the answers

What can happen if there's a break in the earthed circuit?

Electric shock could occur Signup and view all the answers

What must be observed according to Section 'J' of the permanent way manual?

Specific procedures for insulated tool usage Signup and view all the answers

Which of the following statements is true regarding the return current in rails?

It creates potential differences that can be dangerous Signup and view all the answers

What is a critical precaution when approaching signaling circuits?

Ensure all circuits are de-energized Signup and view all the answers

Where are signals typically located in relation to the track?

On the left side of the track Signup and view all the answers

What is the minimum distance required between the traction mast and the signal post?

30 meters Signup and view all the answers

What should be done if the traction mast is located less than 30 meters in front of the signal post?

Request dispensation to reduce the distance Signup and view all the answers

What is desirable for signal location on tangent tracks?

Signal should be within the OHE structure Signup and view all the answers

Who is responsible for examining sites with obstructions for signal placement?

The signal sighting committee Signup and view all the answers

What is essential about the height of the signal post?

It should be high enough for clear visibility Signup and view all the answers

What is the consequence if a signal post infringes upon the schedule of dimensions from the nearest track?

It must be relocated or modified Signup and view all the answers

What should the spacing of OHE masts conform to?

Drawing No. 22-D6 Signup and view all the answers

What is the maximum permissible parallelism for a point machine with an AC immunity level of 400 volts in a double line configuration?

2200 meters Signup and view all the answers

Which component is required for the electric operation of point detection circuits?

AC-immunized relay Signup and view all the answers

What is the factor of safety applied to the maximum permissible lengths for point machines?

1.5 Signup and view all the answers

In RE areas, what is the reason for installing insulators on the point rods?

To protect operating staff from induced voltage and rail voltage Signup and view all the answers

What is a notable characteristic of a 3-phase point machine?

It is inherently immune to induced voltage Signup and view all the answers

What is the maximum permissible length for commonly used point machines with an AC immunity level of 160 volts in a single line configuration?

910 meters Signup and view all the answers

How close should the insulator be placed in the lead out of each rod as per the specified instructions?

As close to the cabin as possible Signup and view all the answers

What mechanical operation measure is necessary for the protection of operating staff?

Specific gear and equipment Signup and view all the answers

What is the required height of the centre line of the red signal above rail level?

3.65 meters Signup and view all the answers

What is the minimum distance required behind the signals where no OHE structures should be provided?

600 meters Signup and view all the answers

If a portal drop arm must be located behind a signal, what special consideration is required?

The signal shall be mounted on an offset bracket. Signup and view all the answers

What should be checked for signal visibility after the OHE work is completed?

By the Official in charge after each phase Signup and view all the answers

What measures should be taken if visibility of a signal is found to be inadequate?

Impose suitable speed restrictions and take steps to improve visibility. Signup and view all the answers

What must be considered when installing portal drop arms with respect to signals with Junction Indicators between tracks?

Precautions and parameters must follow the same as without Junction Indicators. Signup and view all the answers

What is the maximum height for any part of a signal without a route indicator above rail level?

5.2 meters Signup and view all the answers

Study Notes

Requirements of Signalling in 25KV AC Electrified Areas

Objectives:
- Ensure signalling equipment functions normally in the presence of traction current.
- Prevent interference from the traction system causing false indications or unsafe operation, even with faulty systems.
- Protect equipment and personnel from electrical shock.

Factors Affecting Signalling in AC Electrified Areas

Visibility: Proper OHE (Overhead Line Equipment) placement during design is crucial for clear signal visibility. Protective shields are necessary where electrical clearances cannot be maintained.
Electrical Clearances: Signals need sufficient electrical clearance from live OHE to prevent issues.
Traction Return Current: Current flowing through traction return lines can affect signals.
Electromagnetic Induction: Induction from the traction system can affect signalling circuits.
Electrostatic Induction: Transferring circuits to underground, metal-sheathed cables helps eliminate this effect.

Signal Structures in Electrified Areas

Colour Light Signals: Only colour light signals are used in electrified areas.
Clearances: Masts, wires, and supports must not obstruct signal visibility; minimum clearances from live OHE parts are essential.
Signal Location: Signal location is determined by signal clearance diagrams, taking into account visibility for train operators, and confirmed by a Signal Sighting Committee.
Clearances for Safety: Personnel should maintain a minimum 2-meter distance from live OHE parts. Shielding or protective measures are needed when this distance can't be maintained.

Signaling Circuits in Electrified Areas

Maximum Length of Parallelism: Signaling line circuits have length restrictions to limit induced voltages from traction systems to a safe level. Sections might be necessary.
External Circuits: Aerial circuits in electrified areas are generally not allowed.
Cable Usage: Specific cable types meeting voltage limits are required to protect equipment and staff.
Polarized Relays: These are not suitable for external circuits in AC electrified areas.
Batteries and Wiring: Batteries and wiring in signalling equipment must be insulated from the ground.
Separate Batteries/DC-DC converters: Separate systems for external and internal circuits are required.
Distance Restrictions: Distance between signal control relays and the signal itself is limited to prevent undesirable voltage induction.

Point Operation and Detection

Point Operation: Points can be operated mechanically or electrically.
Point Detection: AC immune relays for point detection are required for protection from induced voltages.
Maximum Permissible Length: The maximum permissible distance between point detection devices and the point motor itself for each machine type is given.
3-Phase Machines: These are inherently immune to induced voltages.

Rod Runs in Electrified Areas

Insulated Rod Joints: Insulators are important to prevent induced voltages from reaching personnel. The distance between insulators along runs is limited.
Safety Measures: Personnel working with rods must follow safety precautions, including using insulated tools and maintaining minimum clearances to reduce the risk of electrical shock.

Protection for Staff

Proximity to Live Conductors: Staff need to be aware of the risk of contact with live conductors.
Return Currents: Understanding how return currents affect potential differences across rails is crucial for safety.
Induction: Staff working near overhead equipment should be aware of induced voltages in metal objects.
Protection Measures: Staff working in electrified areas need insulated tools and follow procedures for safety.

Breakage of Catenary/Contact Wire

Safety Procedures: Safety measures for signalling personnel when overhead wiring is damaged are specified.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz covers the requirements and factors affecting signalling equipment in 25kV AC electrified areas. It focuses on ensuring normal operation amidst traction currents and preventing interference. Key aspects like visibility, electrical clearances, and types of induction that impact signalling are discussed.