Signaling Circuit Design Criteria

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Questions and Answers

What color indicates that the crank handle is locked and the CH key is in position?

Yellow Steady

What indication does the control panel provide when the CH key is released but remains inserted?

Red Flashing

What mechanism should be in place to prevent excessive current damage to indication lamps?

Return wires must be suitably bifurcated.

What visual cue is given when a route cancellation is initiated during an approach locked condition?

The respective signal lock indication (white light) starts flashing. Signup and view all the answers

When the gate is closed and locked, what color is the control panel indication?

Yellow Steady Signup and view all the answers

What should occur if a push button on the control panel is left pressed?

A buzzer should indicate the button's status. Signup and view all the answers

Describe the indication when the emergency CH key release control is activated.

Yellow Flashing with a 120 Seconds timer in progress. Signup and view all the answers

What light condition indicates that the gate is open?

Red Steady Signup and view all the answers

What is the purpose of lighting the more restrictive aspect automatically in case of main signal failure?

To ensure safety by preventing misinterpretation of signal indications. Signup and view all the answers

Explain the implication of not being able to clear a signal in the rear if the ON aspect fails.

It prevents unintended signal clearance, maintaining safety until the issue is resolved. Signup and view all the answers

What types of locking are mentioned as necessary for circuit design?

Fouling protection, approach locking, indication locking, route locking, siding control key locking, and crank handle locking. Signup and view all the answers

What is required regarding the communication of point control relays before a signal displays an 'OFF' aspect?

The correspondence of point control relays and point indication relays must be proved. Signup and view all the answers

Why are starter signals automatically replaced to 'ON' after the passage of a train?

To ensure that the system resets for the next train and maintains safe operations. Signup and view all the answers

Describe the locking condition for main signals concerning level crossing gates.

The main signal cannot assume 'OFF' unless all interlocked level crossing gates on its route are closed and locked. Signup and view all the answers

What conditions must be met before opening an interlocked gate at a station?

The concerned signal must be replaced to 'ON' and the route up to the gate must be released. Signup and view all the answers

How do advanced starter signals function differently at way side stations compared to junction stations?

Advanced starter signals are not required at way side stations but are necessary at junction stations with diverging tracks. Signup and view all the answers

What is the purpose of back locking in gate signals?

The purpose of back locking in gate signals is to ensure that the signal position is maintained correctly to prevent accidents when there is an approaching train. Signup and view all the answers

Explain why isolation points of catch sidings may operate automatically.

Isolation points of catch sidings may operate automatically after the passage of a train to their isolation position when sectional route release is provided. Signup and view all the answers

How does the CH/NX control affect point operations?

Once CH/NX control is released, points cannot be operated by route setting but can still be operated individually until the CH/NX key is inserted. Signup and view all the answers

What safeguards are in place to prevent false indications in point control circuits?

Point control circuits are designed to prevent cross connections or short circuits from operating a point or giving false indications. Signup and view all the answers

Describe the actions triggered by failures in point zone track circuits.

In case of point zone track circuit failure, emergency operations allow the concerned point to be operated provided the interlocking is free. Signup and view all the answers

Why are keys controlling hand-operated points electrically locked?

Keys controlling hand-operated points are electrically locked by the approach track back locking track circuit to prevent operation in the face of an approaching train. Signup and view all the answers

What is the role of the time lag in cutting off motor feed for point movements?

The time lag in cutting off the motor feed for point movements allows for safety by stopping the motor if there is an obstruction after a predetermined duration. Signup and view all the answers

What minimum interlocking is required between points according to the principles outlined?

Interlocking between points shall be provided only to the minimum extent necessary to ensure safe train operations. Signup and view all the answers

Study Notes

Design Criteria of Signalling Circuits

Detailed circuit designs may be required for route setting (Entry/Exit principle) or non-route setting (individual point operations) installations, or alterations.
Designs must meet requirements for 25 kV AC electrified areas (Chapter 22 of SEM).
Designs adhere to approved signalling plans, control tables, control panel diagrams, and relay analyses.
Designs accommodate specific equipment types (distributed/central electronic interlocking, MSDAC, SSDAC, UFSBI, etc.) and interfacing features.
Use of dual OFC cables in distributed electronic interlocking is preferred for reduced copper cable extent and alternate failure paths.
Drawings and designs follow typical templates, RDSO standards, industry best practices, and reliability, availability, maintenance, and safety guidelines.

Control Panels - General

Illuminated diagram layouts on control panels should be well-proportioned, using domino panels for potential future expansions, and distinguished areas by color.
Operating members (route switches, buttons, point switches, etc.) are usually shown on the illuminated diagram itself in geographical order.
Separate diagrams for indication and operating member consoles are sometimes provided.
Installations that aren't route-setting type allow for individual point operation.
Route setting is based on the "Entry/Exit" principle.
Each route has two push buttons: one at the entrance and one at the exit.

Non-route Setting Installations

Individual push button operation clears signals, possibly with group buttons or a common switch for conflicting signals (entrance/exit).
Separate individual push buttons or two/three position switches for control of individual points are provided,
Route selection with alternate routes/approaches is allowed.

Control Panel Indications

Individual point operation arrangements are provided.
Emergency operation of points, where provided, records operations on a counter.
Facility for slotting, cabins, crossings, and crank handles is needed.
Cancellation of slots, with a delay, uses a cancellation button with an entrance/exit button.
Operation recording for slots and cancellation is provided by a counter.
'ON'/'OFF' operated signal positions from the panel cannot be changed after the SM key is removed, though the signal can be returned to 'ON' position without altering route.
Indication of yard and critical maintenance information is presented.
Point positions are indicated by lights (white/yellow/green).
Point locking indication is provided by a small white light.
Route settings and locking are shown by white lights on sections.
Occupied track circuits are shown by red lights.
Power supply status indications are provided.
Approach track circuits are indicated.
Advance approach warnings use flashing lights or other indications with audible warnings.
Signal lamp failures alarm by red indication and audible alert.
Indication of aspects for the corresponding signal in the 'OFF' mode.
Failure conditions or status of aspects are shown with flashing indications.
Shunt signal aspects are shown by a white strip light (horizontal).
'A'/'AG' marker light indications are provided.

Track Circuit Indications

Indication of occupied track circuits using a row of red lights.
Red lights extinguish when tracks are not occupied.

Other Crucial Aspects

Detailed signal circuit design for 25kV AC electrified areas.
Non-use of common return wires in critical circuits.
Limitation on number of metal-to-metal relay contacts (45 max).
Design mandates route setting interlocking for new installations.
Correct point settings, overlap, and isolation are critical during route setting.
Proper clearance for slot, road traffic, and overlap is handled by signal clearance.
Requirements for clearing Calling-On and shunt signals are noted.
White indication is required for Block control on the last stop signal when used in Absolute Block Systems.
Other conditions for the Non-Route setting type are mentioned in the text.
Specific conditions for route release circuits are noted..

Additional Signal and Control Information

Procedures, controls, and key aspects for route control, point operation, signals, and other related aspects are detailed for both route-setting and non-route-setting types of installations

Electronic Devices

The equipment design includes features to self-detect component failures and ensure signal display of most restrictive indications.
Safety measures are in place to handle open/short circuit conditions and variations in component values.
Physical layout prevents external objects from causing short circuits.

Track Circuits & Axle Counters

Standardized train detection procedures using track circuits and axle counters are followed.
DC track relays are centrally located.
Extensive track circuiting is done to cover the station section

Signalling Cables

Provisions for signalling cables conform to associated standards.
The yard requires extra cable pairs for maintenance considerations, especially during expansions.
Earth leakage detectors are recommended.

Point Machines Operation

Crank hand operation with distinct group wards is considered.
Safety mechanisms and controls for point operation are considered.

Advanced Aspects of Interlocking

Features for Advanced Starter at Junction Stations, including the automatic resetting of signals based on train passage and controlled delays, are examined
Special considerations for level crossings, including locking and signals, are detailed.

Signal Control Circuits aspects

Conditions for setting and locking signals in route-setting, as well as non-route-setting installations, are explained.
Consideration of procedures for clearing signals when conditions meet the requirements for specific types of signals are noted.
Instructions on handling and restoring signals in emergency situations are provided to ensure safety

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Description

This quiz covers the essential design criteria for signaling circuits, focusing on requirements for various electrified areas and the integration of specific equipment types. It also highlights the importance of adhering to approved plans and best practices in the field. Prepare to test your knowledge on circuit designs, control panels, and industry standards.