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What is the primary objective of the requirements for signalling in a 25 KV AC electrified area?
What is the primary objective of the requirements for signalling in a 25 KV AC electrified area?
Which factor is NOT mentioned as affecting signalling in an AC electrified area?
Which factor is NOT mentioned as affecting signalling in an AC electrified area?
To maintain electrical clearances, what must be done if a minimum distance of 2 meters cannot be achieved?
To maintain electrical clearances, what must be done if a minimum distance of 2 meters cannot be achieved?
What is the purpose of installing protective wire-mesh screens near signalling equipment?
What is the purpose of installing protective wire-mesh screens near signalling equipment?
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How is electrostatic induction practically eliminated according to the requirements?
How is electrostatic induction practically eliminated according to the requirements?
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Which of the following describes electromagnetic induction in rail signalling?
Which of the following describes electromagnetic induction in rail signalling?
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What type of bond must be provided by the electrical department in yard and block sections?
What type of bond must be provided by the electrical department in yard and block sections?
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What is a required practice if it is impossible to maintain electrical clearances from live OHE?
What is a required practice if it is impossible to maintain electrical clearances from live OHE?
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In which areas are the diagrams for Broad Gauge not applicable?
In which areas are the diagrams for Broad Gauge not applicable?
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What is the normal height of the contact wire at supports for Broad Gauge?
What is the normal height of the contact wire at supports for Broad Gauge?
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What clearance must be maintained from the live parts of the O.H.E. under normal conditions?
What clearance must be maintained from the live parts of the O.H.E. under normal conditions?
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Where may the contact wire be lowered due to limited clearance?
Where may the contact wire be lowered due to limited clearance?
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What should be provided on a signal post if it is within 2 meters of a live conductor and screening is not practicable?
What should be provided on a signal post if it is within 2 meters of a live conductor and screening is not practicable?
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What is the highest normal height of the catenary wire for Broad Gauge?
What is the highest normal height of the catenary wire for Broad Gauge?
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What should be done if the signal post fittings fall within 2 meters of a live conductor?
What should be done if the signal post fittings fall within 2 meters of a live conductor?
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What allowance does the clearance diagram make for regarding catenary and contact wires?
What allowance does the clearance diagram make for regarding catenary and contact wires?
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Which factor does NOT influence the value of induced voltage in cables?
Which factor does NOT influence the value of induced voltage in cables?
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What type of signals shall be used in electrified areas?
What type of signals shall be used in electrified areas?
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Who is responsible for checking the actual visibility of signals?
Who is responsible for checking the actual visibility of signals?
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Which clearance diagram is used for tangent tracks and those with super elevation less than 60 mm?
Which clearance diagram is used for tangent tracks and those with super elevation less than 60 mm?
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What is required when a signal post or its fittings infringe into the shaded area of the clearance diagram?
What is required when a signal post or its fittings infringe into the shaded area of the clearance diagram?
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Which of the following is NOT a factor affecting induced voltage as mentioned?
Which of the following is NOT a factor affecting induced voltage as mentioned?
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What does the un-shaded portion of the clearance diagram represent?
What does the un-shaded portion of the clearance diagram represent?
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What must be maintained from the live parts of the O.H.E.?
What must be maintained from the live parts of the O.H.E.?
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What precaution should be taken if tools or equipment may come within 2 meters of live equipment?
What precaution should be taken if tools or equipment may come within 2 meters of live equipment?
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What is required if the neutral section is located after a stop signal?
What is required if the neutral section is located after a stop signal?
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Where should a neutral section ideally be located?
Where should a neutral section ideally be located?
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What is the preferred distance for a neutral section away from a stop signal on flat gradients?
What is the preferred distance for a neutral section away from a stop signal on flat gradients?
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What should the SSE/JE (Signal) do regarding safety instructions?
What should the SSE/JE (Signal) do regarding safety instructions?
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What should be avoided when positioning neutral sections in terms of train operation?
What should be avoided when positioning neutral sections in terms of train operation?
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What height and distance requirements do Drg.Nos. 22-D4 and 22-D5 illustrate?
What height and distance requirements do Drg.Nos. 22-D4 and 22-D5 illustrate?
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What should be done if modifications to comply with guidelines are difficult?
What should be done if modifications to comply with guidelines are difficult?
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Where should signals normally be located in relation to the track?
Where should signals normally be located in relation to the track?
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What is the minimum distance required between a traction mast and a signal post to ensure visibility?
What is the minimum distance required between a traction mast and a signal post to ensure visibility?
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In what situation may the distance requirement between traction masts and signal posts be reduced?
In what situation may the distance requirement between traction masts and signal posts be reduced?
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What is an important consideration when setting signal posts on curved tracks?
What is an important consideration when setting signal posts on curved tracks?
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What is the requirement for the height of the signal post?
What is the requirement for the height of the signal post?
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What should be avoided regarding the placement of traction masts in relation to signal posts?
What should be avoided regarding the placement of traction masts in relation to signal posts?
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What is a guideline regarding the signal's location on tangent tracks?
What is a guideline regarding the signal's location on tangent tracks?
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What should not infringe upon the schedule of dimensions from the track's centerline?
What should not infringe upon the schedule of dimensions from the track's centerline?
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What is the standard height of the center line of the red signal above rail level?
What is the standard height of the center line of the red signal above rail level?
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What is the minimum distance that OHE structures should be kept from signals located between tracks?
What is the minimum distance that OHE structures should be kept from signals located between tracks?
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What precautions should be taken for portal drop arms located in rear of signals?
What precautions should be taken for portal drop arms located in rear of signals?
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What action should an official take if signal visibility is deemed inadequate after any phase of OHE work?
What action should an official take if signal visibility is deemed inadequate after any phase of OHE work?
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For signals with junction indicators outside tracks, the setting distances of OHE masts should align with which document?
For signals with junction indicators outside tracks, the setting distances of OHE masts should align with which document?
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What is the maximum height without a route indicator for a signal above rail level?
What is the maximum height without a route indicator for a signal above rail level?
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How often should signal visibility be checked by the official in charge?
How often should signal visibility be checked by the official in charge?
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What is required for signals with junction indicators between tracks?
What is required for signals with junction indicators between tracks?
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Study Notes
Signalling in 25 KV AC Electrified Areas
- Objectives: Ensure signalling equipment functions normally in the presence of traction current. Prevent false indications from the traction system. Safeguard equipment and staff from electric shock.
Factors Affecting Signalling
- Visibility: Signal visibility affected by overhead line equipment (OHE) structures. Electrical clearances of signals from live OHE are crucial.
- Traction Return Current: Can cause interference in signalling systems.
- Electrostatic and Electromagnetic Induction: Can induce voltages and currents in parallel conductors (rails, traction return, cables), affecting signalling and telecommunication systems. Induced voltage depends on various factors (cable parallelism, soil conductivity, screening efficiency).
Visibility of Signals
- OHE structures should be designed to ensure signal visibility.
- Protective shields for signal structures may be needed where electrical clearances cannot be maintained.
- Layout plan for OHE should be based on approved signalling plan.
- Protective wire mesh screens are required where signal clearance from live OHE conductors is more than 2 meters.
- OHE bonds (structural, longitudinal, cross bonds) are provided by the electrical department for proper functioning of field signaling equipment (fastened to the structure/mast/rails, insulated for portions under positive rail).
Electrostatic Induction Elimination
- Transferring circuits into underground metal-sheathed cables helps eliminate electrostatic induction.
Signal Structures in Electrified Areas
- Only colour light signals are used in electrified areas.
- Signal masts, insulators, wires, and supports must not obstruct signal visibility.
- Signals should be erected to maintain a minimum clearance from live OHE parts.
- Signal location and required protection are determined based on signal clearance diagrams for broad gauge (different diagrams for tangent tracks, curves with varying degrees of super elevation).
- Signal posts and fittings must not infringe on marked safe areas.
Signal Clearances for Safety
- No one should approach live OHE parts closer than 2 meters.
- Protective iron screening is necessary if signal posts come within 2 meters of live 25 KV conductors.
- Caution boards are placed on signal posts if protective screening is not feasible.
Location of Neutral Section
- Neutral sections are located away from stop signals and level crossings (ideally on tangents).
- The distance between the signal and neutral section is crucial and must be sufficient for the train to gain safe speed to coast through the neutral section without stalling (at least 1600 meters on slight gradients and up to 2500 meters for sharper gradients).
- PTFE type short neutral sections are located 400 meters after and 200 meters before a stop signal on level tangent tracks.
Signal Erection in Electrified Areas
- Signals are typically located on the left side of the track, exceptions exist.
- Proper OHE design is essential for signal visibility (offset brackets if necessary, avoiding obstructions within 30 meters of the signal, sufficient height for clear visibility).
- Signal posts and components should not infringe on other signal components.
- Visibility of signals should be checked both day and night to ensure adequate speed restrictions; speed restrictions might be necessary.
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Description
This quiz covers the critical aspects of signalling equipment's functionality in electrified areas under 25 KV AC systems. It highlights factors such as visibility, traction return current, and the impact of electrostatic and electromagnetic induction on signalling and communication systems. Understanding these concepts is essential for ensuring safety and reliability in railway operations.
