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Questions and Answers
What happens to the main signal aspect lighting if there is a failure at the site?
What happens to the main signal aspect lighting if there is a failure at the site?
The more restrictive aspect is lit automatically.
Why is it important for a signal to automatically replace to 'ON' after a train passes?
Why is it important for a signal to automatically replace to 'ON' after a train passes?
It maintains operational integrity and ensures that signals are updated in real-time to reflect current track usage.
What is the requirement for starter signals at junction stations?
What is the requirement for starter signals at junction stations?
Starter signals must be released by advance starters at diverging ends and where specific track circuiting is not in place.
Describe the locking condition of interlocked level crossing gates in relation to main signals.
Describe the locking condition of interlocked level crossing gates in relation to main signals.
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What is the role of control circuits in fouling protection and locking mechanisms?
What is the role of control circuits in fouling protection and locking mechanisms?
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What ensures the proof of aspect indication in signal circuits?
What ensures the proof of aspect indication in signal circuits?
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How does the design of circuits help during failures of the ON aspect?
How does the design of circuits help during failures of the ON aspect?
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What is required to open an interlocked gate at a station?
What is required to open an interlocked gate at a station?
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What must be provided to indicate the satisfactory working of an approved electronic flasher relay?
What must be provided to indicate the satisfactory working of an approved electronic flasher relay?
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What should be prepared and approved before designing detailed circuits for interlocking and circuit requirements?
What should be prepared and approved before designing detailed circuits for interlocking and circuit requirements?
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What restriction is placed on signal circuits regarding changes in signal aspect?
What restriction is placed on signal circuits regarding changes in signal aspect?
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What is the maximum number of contacts that can be used in series in a circuit when relays other than 24 V, 1000 ohm are used?
What is the maximum number of contacts that can be used in series in a circuit when relays other than 24 V, 1000 ohm are used?
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Which type of interlocking should be used for all new installations according to the guidelines?
Which type of interlocking should be used for all new installations according to the guidelines?
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What conditions must be met for the route setting and clearance of signals?
What conditions must be met for the route setting and clearance of signals?
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What type of relay contact proving should be done in circuitry?
What type of relay contact proving should be done in circuitry?
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What must be proven in the signal clearance for crank handle keys?
What must be proven in the signal clearance for crank handle keys?
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What function does the latch relay serve in point control circuits?
What function does the latch relay serve in point control circuits?
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Describe the purpose of the mid-stroke point reversal feature.
Describe the purpose of the mid-stroke point reversal feature.
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What is the role of the Maintenance Terminal in the Electronic Interlocking system?
What is the role of the Maintenance Terminal in the Electronic Interlocking system?
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Explain what is meant by 'Block Working' in Electronic Interlocking systems.
Explain what is meant by 'Block Working' in Electronic Interlocking systems.
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What does the self-detecting principle in fail-safe design entail?
What does the self-detecting principle in fail-safe design entail?
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Why is continuous energization critical in fail-safe circuits?
Why is continuous energization critical in fail-safe circuits?
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How should external factors be mitigated in the physical design of fail-safe equipment?
How should external factors be mitigated in the physical design of fail-safe equipment?
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What guidelines should be followed in the design, installation, and maintenance of electronic systems?
What guidelines should be followed in the design, installation, and maintenance of electronic systems?
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What is the recommended color for earthing wires from electronic interlocking subsystems for quick identification?
What is the recommended color for earthing wires from electronic interlocking subsystems for quick identification?
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Why should the earth wire from the surge protection device to the main earth terminal be as straight and short as possible?
Why should the earth wire from the surge protection device to the main earth terminal be as straight and short as possible?
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What minimum cross-sectional area is specified for copper earth wires to ensure adequate current carrying capacity?
What minimum cross-sectional area is specified for copper earth wires to ensure adequate current carrying capacity?
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What should be avoided when installing earth wires to ensure their proper function?
What should be avoided when installing earth wires to ensure their proper function?
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What is the purpose of copper tape as a bonding ring conductor in the relay room?
What is the purpose of copper tape as a bonding ring conductor in the relay room?
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What is the maximum track circuit length that QBAT can be used with a choke in RE areas?
What is the maximum track circuit length that QBAT can be used with a choke in RE areas?
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Describe the main function of Timer Relays in signaling circuits.
Describe the main function of Timer Relays in signaling circuits.
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What type of relay uses a heating element and a neutral line relay to operate after a time delay?
What type of relay uses a heating element and a neutral line relay to operate after a time delay?
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What unique feature does the QBAT relay possess to assist in its operation?
What unique feature does the QBAT relay possess to assist in its operation?
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List the four types of Time Element Relays mentioned in the content.
List the four types of Time Element Relays mentioned in the content.
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What are the key characteristics of the QSPA1 relay?
What are the key characteristics of the QSPA1 relay?
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Describe the function of the QL1 relay and its operational mechanism.
Describe the function of the QL1 relay and its operational mechanism.
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What type of relays should be used in electrified areas according to the information provided?
What type of relays should be used in electrified areas according to the information provided?
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What distinguishes the QT2 relay from traditional Q-Series line relays?
What distinguishes the QT2 relay from traditional Q-Series line relays?
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Explain how the QTA2 relay achieves AC immunity.
Explain how the QTA2 relay achieves AC immunity.
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What are the pick up voltage and current specifications for the QTA2 relay?
What are the pick up voltage and current specifications for the QTA2 relay?
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What is the significance of the back contact in the QT2 relay?
What is the significance of the back contact in the QT2 relay?
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For new installations in RE areas, what is the outlet of using QTA2 relays?
For new installations in RE areas, what is the outlet of using QTA2 relays?
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Study Notes
Design Criteria of Signalling Circuits
- Detailed designs for interlocking circuits may be required for route setting (entry/exit principle) or non-route setting (individual point operation).
- Designs must meet requirements for 25 kV AC electrified areas (as per Chapter 22 of SEM).
- Designs must align with approved signalling plans, control tables, control panel diagrams, and relay contact analysis/rack arrangements.
- Compatibility with various equipment (e.g., types of electronic interlocking, interfacing features) should be considered.
- Dual OFC in distributed electronic interlocking is desirable for reduced copper cabling and alternate failure paths.
- Designs must adhere to typical templates, RDSO standards, industry best practices, and principles of reliability, availability, maintenance, and safety.
Control Panels
- Illuminated diagrams on control panels must be well-proportioned. Domino panels are preferable where additional facilities are anticipated.
- Areas covered by each track circuit should be distinguished by different colours.
- Operating members (route switches, point switches, etc.) should be placed in geographical order on the illuminated diagram (or a console).
- Installations using individual point operation may be set on an 'entry/exit' principle.
- Route setting installations use two push buttons (one at the entrance, one at the exit).
- Non-route setting types use individual point operation.
- Signal clearing may involve individual push buttons, group buttons, or a common switch for concurrent signals.
Control Panel Indications
- Provision for individual point operation is mandatory.
- Records of emergency point operations (during track circuit failures) must be kept.
- Slotting facilities for connecting cabins, ground frames, and level crossings should be available.
- Cancellation of slot operations should accommodate a delay period for route holding or locked route status.
- Control panel operation must not impact the last operational setting of signalling equipment. Signals should be able to be returned to 'ON' without affecting route settings when the key is removed
- Displays of yard position, and important indications for maintenance personnel.
Point Indications
- Point position is indicated by white/yellow/green lights near switches and white strip lights in the point zone..
- During point operation, the corresponding point light should flash until it locks.
- Indicate locked point position with a small white light near the switch.
Route Indications
- Route setting and locking status is indicated using white lights (minimum two) on each track section.
- Complete route sections are illuminated with white lights when the route is correctly set.
- Route lighting changes to red while a train occupies it, then returns to white when clear.
Signal Indications
- Red light shows "stop" signal 'ON'.
- Yellow light indicates "permissive" signal 'ON'.
- Green/yellow/double yellow light signifies "OFF" signal aspect.
- Flashing green/yellow/red lights indicate signal aspect failure.
Track Circuit Indications
- Red lights (at least two) indicate track circuit occupancy.
- The lights extinguish when the track is unoccupied.
Power Supply Indication
- Indication of various power sources (mains, diesel generator, or catenary) should be given appropriately.
Other Indications
- Approach track circuits are displayed on illuminated diagrams.
- Advance approach warning of trains may include flashing lights and/or audible warnings. An indication should be provided to silence the audible warnings by a pushbutton.
- Signalling aspect/route aspect failure should be indicated by a red light.
- Ensure that a circuit failure results in the display of a most restrictive aspect.
- Control panel displays should show the 'locked' or 'free' status of crank handles.
- Displays should indicate if a CH key is present, and if the control is not taken from the control panel.
- The gate control status should also be displayed on the panel (e.g. Yellow Steady if closed/locked, Yellow Flashing if released but not open, Red Steady when open). Ensure there is a provision for a counter to operate.
- The current and appropriate relay and electrical considerations should be noted for return wires.
- Indicate whether an approved electronic flasher relay (other than mercury type) is provided.
- Clear representation of train detection and route locking criteria is displayed.
Route Setting Type
- The route setting and clearance conditions adhere to specific criteria.
- Ensure all points are set and locked. Overlaps and isolations are similarly addressed.
- Track circuits in the route and overlaps are clear and free from interference/faults.
- Signal stop aspects are not blank.
- Route interlocks are established electronically.
- Approach and dead approach locking for manual stop signals is a mandatory feature.
- Level crossings, ground frames, cabins, and sidings have interlocking mechanisms.
Non-Route Setting Type
- The points in the selected route, along with any required overlap and isolation, are positioned appropriately using switches or pushbuttons in conjunction with a group pushbutton.
- SM key is in.
- The interlocking is free.
- Points including hand-operated points within the route, involving overlaps and isolations (as applicable), are set, locked, and identified promptly.
Route Release Circuits
- Complete route release (including overlaps, if any) should be activated efficiently.
- Route release should be sequential, following signal 'ON' status and operated button/switch.
- Separate circuits exist for the release of individual route sections.
- Sectional route release is implemented for installations with more than a hundred routes. Provisions are made for the automatic release of a route following the authorized passage of a train.
- There are specifications for delays in route release during emergency situations based on the type of approach track occupancy.
Section 6 and 7
- Maintenance and specifications for installation, testing, and maintenance of electronic interlocking.
- Surge and lightning protection for related electrical and electronic equipment is included.
- Earthing specifications for the equipment are included.
Relay Interlocking:
- Relays and relay racks, including their connection and configuration.
- Specific safety characteristics for connections required.
- Installation, maintenance, and periodic/general maintenance requirements and standards.
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Description
Test your knowledge on the design criteria for signalling circuits, focusing on interlocking circuits, compatibility with equipment, and adherence to industry standards. This quiz covers the essential requirements for 25 kV AC electrified areas and control panel specifications. Challenge yourself and see how well you understand the principles of reliability and safety in signalling design!
