Optical Lenses and Signal Visibility Quiz

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Questions and Answers

What is one advantage of a step lens over a plane convex lens?

Narrower refracting surface

Increased thermal endurance (correct)

Increased weight

Greater light absorption

What type of lens combination collects more light than a single optical lens?

Doublet lens (correct)

Convex lens

Single step lens

Plane convex lens

How much light does the strongest lens of diameter 213 mm typically collect?

6% (correct)

50%

20%

25%

Which factor decreases when using a spread light lens with greater angular deflection?

Main beam efficiency Signup and view all the answers

What is the approximate visibility range of well-aligned signals under bright sunlight?

More than 1000 m Signup and view all the answers

What is often installed on signals to aid visibility for drivers standing close by?

Close up indications Signup and view all the answers

What can be a limitation of using reflectors in signal visibility?

Phantom indications from sun rays Signup and view all the answers

What does the combination of two lenses, known as toric combination, collect in terms of light?

50% Signup and view all the answers

What issue does the hot spot problem cause in lamps?

Reduced life of the lamp Signup and view all the answers

What is the purpose of the lamp-proving relay (MECR) in triple pole lamps?

To switch on the auxiliary filament when the main filament fails Signup and view all the answers

What is the wattage rating of the auxiliary filament in the SL 21 double pole lamp?

16 W Signup and view all the answers

Which type of lamp has both filaments rated at 12 V / 33 W?

SL 35B Signup and view all the answers

What feature distinguishes triple pole lamps from other lamp types?

The common connection of the filaments to the shell Signup and view all the answers

How does the SL 35A triple pole lamp differ in filament placement from SL 21?

Both filaments are horizontally located Signup and view all the answers

Why is the auxiliary filament in SL 21 rated for less wattage?

To provide a dim light when the main filament fails Signup and view all the answers

What is the primary function of signalling lamps as mentioned?

To indicate signals or points behind levers Signup and view all the answers

What is the primary drawback of the signaling system using lamp proving units?

It requires separate voltage supplies. Signup and view all the answers

What is a common cause of signaling failures according to the provided information?

No light from signaling lamps. Signup and view all the answers

What impact does the fusing of signal lamps have on train punctuality?

It causes delays and increases signal failures. Signup and view all the answers

What does the schedule for replacement of signal lamps vary by?

Railway company and division. Signup and view all the answers

In the case of using 2-filament lamps, what issue arises if the main filament fuses?

Train detentions increase. Signup and view all the answers

What type of lamps are used in colour light signaling without a cutting-in arrangement?

SL 21, 12 V / 33 W double filament 3-pin lamps. Signup and view all the answers

What is the replacement schedule for ON aspect signal lamps?

Forty-five days or thousand hours. Signup and view all the answers

What is the consequence of having both filaments lit simultaneously in a 2-filament lamp system?

It leads to a shorter lifespan of the lamps. Signup and view all the answers

What is required for the DIST DR to pick up?

The train must be received or run through on the main line. Signup and view all the answers

What can cause a signal to go 'blank'?

Failure of signal lamp or power interruption. Signup and view all the answers

What does a double yellow signal indicate to the driver?

The driver may stop at the main line starter. Signup and view all the answers

What is a benefit of the distant signal system for drivers?

Ability to know signal information in advance. Signup and view all the answers

What is the typical lifespan of a traditional filament lamp used in signals?

1000 hours Signup and view all the answers

What benefit does the provision of a Second Distant Signal provide?

It improves driver confidence and punctuality. Signup and view all the answers

When will the inner distant signal display a green aspect?

If the home signal displays green. Signup and view all the answers

How does the lifetime of an LED signal unit compare to that of a filament lamp?

LED units have a life of not less than one lakh hours. Signup and view all the answers

What happens when the DG lamp fuses in the inner distant signal system?

The signal will display double yellow. Signup and view all the answers

What is a potential consequence of a blank signal?

Confusion leading to accidents. Signup and view all the answers

Which of the following is NOT an advantage of the distant signal system?

Drivers need to stop less frequently. Signup and view all the answers

How far in advance can a driver know the information about the signals ahead?

2 Km Signup and view all the answers

What must be done after replacing a signal lamp?

Check and adjust focusing. Signup and view all the answers

What aspect does a Distant Signal display when the necessary conditions are met?

A green aspect. Signup and view all the answers

What is the primary function of the inner distant HHR in the signal control circuit?

To pick up yellow when the home signal displays yellow. Signup and view all the answers

Which of the following signals indicates that the driver should stop at the loop starter?

Double yellow with route indicator. Signup and view all the answers

What is the purpose of the gasket made of EPDM rubber in the LED signal unit?

To ensure the unit can withstand environmental severity Signup and view all the answers

What is the minimum illumination required for the Red aspect of the LED signal unit?

50 Lux Signup and view all the answers

What is the visibility requirement for each main aspect of the LED signal unit?

600 m in day light Signup and view all the answers

Which aspect has the highest minimum illumination requirement during operation?

Green aspect Signup and view all the answers

What is the role of the MOV or Gas discharge tube provided at the input terminals?

To protect against power surges Signup and view all the answers

What is the diameter of the Main and Calling-On signals display area in the LED signal units?

125 mm Signup and view all the answers

What is the rated wattage at the input terminals of the Main Signal?

15 W Signup and view all the answers

What is the current at rated operation for the Route signal?

25 mA Signup and view all the answers

Signup and view all the answers

Study Notes

Automatic Colour Light Signalling

Automatic block working uses automatic stop signals to control train movements through sections.
Trains are track-circuited throughout the line, with sections controlled by automatic stop signals.
Signal aspects are automatically changed based on the passage of trains through sections.
The system aims to increase line capacity without needing additional stations.

Adequate Distance/Overlap

The minimum overlap distance must be 120 meters between signalling sections, unless stated otherwise.
This overlap ensures the line is clear before a signal can change to "off".

Automatic Stop Signals

These are multiple-aspect colour light signals (either 3 or 4 aspects), with unique numbering systems.
Odd numbers are used in one direction (e.g., UP), and even numbers in the other (e.g., DOWN).
Numbers often use a kilometre-and-pole identification scheme for easier location.
Several numbering methods are used depending on the track configuration and complexity

Track Circuits

Track circuits control the operation of automatic signals.
Circuits can be DC or AC, single or double track-based, depending on the local conditions.
Essential to ensure proper signalling operation.

Four-Aspect Automatic Signalling

For situations in which breaking distance necessitates signals being closer together 4-aspect signalling is employed.
In this system, a signal's aspect changes to Red, Yellow, Double Yellow, or Green as the train progresses through sections.
Signals ensure that adequate braking distances are maintained between trains.

Red Lamp Protection

A system designed to ensure that signals don't go blank if a red lamp fails.
This is crucial in ensuring section safety and preventing accidents.
The circuit uses a relay to detect and prevent a signal from displaying a less restrictive aspect than red due to lamp failures

Cascading Arrangement

An arrangement of signal lamps that functions as backups in case of failures.
If one lamp fails, the other lamps in the same circuit take over to avoid signals going blank.

LED Signal Units

These use solid-state light-emitting diodes (LEDs) and provide a reliable and long-life signalling system.
Compared to traditional filament lamps, they reduce maintenance and energy consumption significantly.
LEDs are self-contained and require no external focusing lenses, hence simpler installation.

Current Regulator Unit

A circuit to ensure a consistent current flow to the LEDs, regardless of fluctuating input voltages.
This ensures stable signal aspect presentation to drivers.
Failure of a single LED won't cause the entire signal aspect to go dark
This unit controls the current flow to each LED in the signal, maintaining consistent brightness.

Signal Tubular Post and Base

Details of the physical dimensions and materials used for construction of signal posts and bases.
These items are crucial for physical infrastructure of signalling systems.

Maintenance Schedule

An outline timetable for various inspection and maintenance activities of signalling equipment

Do's and Don'ts

Guidelines to ensure proper operation and safety during the maintenance and operation of signalling systems
Includes measures to prevent accidents and ensure maintenance is performed correctly.

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Description

Test your knowledge on optical lenses, their advantages, and their applications in signal visibility. This quiz covers key concepts such as lens combinations, light collection, and the specifics of lamp-types used in bright conditions. Perfect for students studying optics or electrical engineering.