Electrical Signaling Circuits Testing and Inspection

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Questions and Answers

What is the purpose of calibration of testing instruments?

To increase the accuracy of readings (correct)

To decrease the cost of maintenance

To check the condition of equipment

To prolong the lifespan of instruments

What should be checked during physical inspection of the installation?

Only the approved plans

Both the equipment condition and approved plans (correct)

Only the equipment condition

Neither the equipment condition nor approved plans

What is the purpose of tagging or marking wires?

To identify the wire at each end (correct)

To reduce the wire's length

To decrease the wire's voltage

To increase the wire's insulation

What should be checked in terms of ventilation during site inspections?

That arrangements for proper ventilation are provided Signup and view all the answers

What type of instruments are suitable for testing electrical signalling circuits?

A variety of instruments, including multi-meters, volt meters, and ammeters Signup and view all the answers

Where should earthing be provided for signal equipment?

At the lever frame and other metallic frames of the cabin Signup and view all the answers

What should be checked in terms of the location of apparatus during site inspections?

That the location is as per approved plans Signup and view all the answers

What is the special case where armouring of unscreened cables needs to be earthed?

When the length of the tail cable exceeds normal prescribed limits Signup and view all the answers

What should be checked in terms of electrolyte and inter-connections during site inspections?

That the electrolyte and inter-connections are in required condition Signup and view all the answers

Why is common earthing not allowed in certain cases?

Because of risk of simultaneous human contact with metallic bodies connected to different earths Signup and view all the answers

What is the purpose of checking the signals, location boxes, and other outdoor equipment during site inspections?

To ensure they are as per approved plans and in good condition Signup and view all the answers

What is the recommended color for earth wires for quick identification?

Green or Green Yellow (GNYE) Signup and view all the answers

What is the maximum earth value required for modern electronic equipment?

1 ohm Signup and view all the answers

How often should the earth value be measured?

Annually during dry season Signup and view all the answers

Why should earth wires be kept as straight as possible?

To prevent coiling Signup and view all the answers

What should be done when it is not possible to provide suitable spacing or partition between metallic objects?

Use a common earth Signup and view all the answers

What is the purpose of grouping location boxes in a large yard area?

To provide convenient telephone communication during maintenance Signup and view all the answers

What is the recommended frequency for System Integrity Testing (SIT) in a signalling installation?

Every 5 years Signup and view all the answers

What is the purpose of a separate pair of conductors for each direction in a large yard area?

To provide separate communication channels for each direction Signup and view all the answers

What is the primary concern during System Integrity Testing (SIT)?

Functional working and safety of both indoor and outdoor signalling equipment Signup and view all the answers

Why is it essential to plan System Integrity Testing (SIT) carefully?

To ensure all necessary resources are available Signup and view all the answers

What is the purpose of providing telephone communication in the RE area?

To facilitate coordination between the cabin and yard during maintenance Signup and view all the answers

What is the recommended duration for non-interlocking/disconnection during System Integrity Testing (SIT)?

Reasonable and commensurate with yard complexity Signup and view all the answers

What is the basis for planning System Integrity Testing (SIT)?

Approved Control Table/Route Chart and Signalling & Interlocking Plan Signup and view all the answers

What is the primary concern during signal testing and checking?

To prevent conflicting or unsafe movement signals Signup and view all the answers

Why should the housing of LED lamp units be kept clean?

To ensure the gasket remains watertight Signup and view all the answers

What should be checked periodically on LED lamps?

Both the bulb's seating and signal visibility Signup and view all the answers

Why must defective LED lamps be replaced immediately?

To maintain signal visibility Signup and view all the answers

What is essential for electric point machines?

Being kept in good condition, free from rust, dust, and dirt Signup and view all the answers

What should be avoided during testing and checking?

All of the above Signup and view all the answers

What is the purpose of insulation tests on cables?

To ensure the cable's electrical insulation Signup and view all the answers

What is the primary consideration when replacing LED lamps?

The lamp's pre-testing procedure Signup and view all the answers

What is the primary function of a Functional Earth in signalling equipment?

To conduct current through earth during normal operation Signup and view all the answers

What is the purpose of bonding the chassis of S&T equipment to BRC?

To ensure equipotentiality Signup and view all the answers

What is the recommended practice for earthing of signal equipment?

Earthing shall be provided as per approved specifications and code of practice Signup and view all the answers

What is the maximum earth resistance specified for signal equipment?

As per RDSO guidelines Signup and view all the answers

What is the purpose of providing a Perimeter Ring Earth (PRE) around a building housing signalling equipment?

To provide a path for surge protection Signup and view all the answers

What is the primary purpose of earthing in signalling equipment?

To protect equipment from lightning surges and other hazards Signup and view all the answers

What is the purpose of connecting the chassis of S&T equipment to MEEB?

To ensure equipotentiality Signup and view all the answers

What is the primary purpose of earthing in terms of human safety?

To prevent electrical shocks Signup and view all the answers

What is the primary reason for avoiding imperfect joints in signalling equipment?

To reduce the risk of electrical shorts and faults Signup and view all the answers

What should be used to strip wire insulation during wire termination?

Wire strippers Signup and view all the answers

Why should multi-strand wires be terminated on terminal lugs and covered with insulation sleeves?

To reduce the risk of electrical shorts and faults Signup and view all the answers

What is the minimum visibility requirement for colour light signals?

As indicated in para 7.1.11 Signup and view all the answers

What type of lamps should be used in colour light signals?

LED lamps Signup and view all the answers

What is the primary consideration when locating colour light signals?

Clear view to the Loco pilot of an approaching train Signup and view all the answers

What should be used to bend wires during wire termination?

Clockwise direction Signup and view all the answers

What type of training should railway conduct?

Periodical training on proper practices for soldering Signup and view all the answers

What is the purpose of the 120-second time delay in the relay interlocking system?

To provide a time buffer for the signal to be restored to normal Signup and view all the answers

What happens when point No. 2 is operated to the reverse position?

The signal 2WBI will turn on Signup and view all the answers

What should be done after operating point knob 2 to normal?

Shunt the track 2T Signup and view all the answers

What is the purpose of controlling point No. 2 to the reverse position?

To clear the signal route No. 2WBI Signup and view all the answers

What happens when the point knob 2 is turned from reverse to normal?

The point will remain locked Signup and view all the answers

Why is it necessary to operate the signal switch/button to normal?

To restore the signal to normal Signup and view all the answers

What is the purpose of de-energizing 2RWKR?

To release the track 2T from occupation Signup and view all the answers

What is the consequence of not operating point No. 2 to the reverse position?

The signal route No. 2WBI will not be cleared Signup and view all the answers

Why is it essential to keep the commutator clean and smooth?

To prevent sparks and overheating Signup and view all the answers

What is the purpose of checking the fixation nuts and screws of newly installed point machines?

To attend to them and readjust where required Signup and view all the answers

What is the recommended frequency for testing and maintaining electrical point detectors (EPD)?

As per Annexure: 19-MS3 Signup and view all the answers

Why is it essential to check the tail cables of point machines?

To inspect for insulation as per periodicity Signup and view all the answers

What is the purpose of conducting obstruction tests on point machines?

To test the machine as per para: 19.3.6 & Annexure 19-MS2 Signup and view all the answers

Why should emery paper not be used to clean the commutator?

It may damage the commutator surface Signup and view all the answers

What should be checked during maintenance of point machines?

The entire machine, including locking dogs and notch slides Signup and view all the answers

Why is it essential to check the rainwater drainage arrangements before the rainy season?

To prevent waterlogging and electrical faults Signup and view all the answers

What is the purpose of dividing points in the yard into convenient groups?

To distinguish particular groups and use crank handles with different wards Signup and view all the answers

What should be done to avoid rodent entry and water ingress?

The excess gap around cable entry to the machine should be plugged Signup and view all the answers

What should be sealed to make them water tight and dust proof?

The wire entrances and electric point machines Signup and view all the answers

What should be locked to provide access only for crank handle and crank handle key?

The cover provided for insertion of crank handle Signup and view all the answers

What should not be tampered or reconditioned?

The notches in stretcher blades Signup and view all the answers

What should be replaced with new ones when worn out?

The locking, driving, and detection slides Signup and view all the answers

What is the purpose of using NX key of different wards?

To achieve the interlocking of crank handles Signup and view all the answers

What type of earth is used to conduct current through earth during normal operation of equipment?

Functional Earth Signup and view all the answers

Why should the crank handles be normally locked?

To prevent unauthorized use of point machines Signup and view all the answers

Where should the chassis of all S&T equipment be bonded to?

BRC Signup and view all the answers

What is the purpose of providing a Perimeter Ring Earth (PRE) around a building housing signalling equipment?

For lightning and surge protection Signup and view all the answers

What should be specified as per OEM and RDSO recommendations?

Maximum earth resistance Signup and view all the answers

What is the purpose of earthing of metal screens of telecommunications cables and equipment?

For reducing Electromagnetic interference Signup and view all the answers

What should be connected to MEEB in the Power Room?

BRC Signup and view all the answers

What is the purpose of earthing of cables, equipment, buildings and structures?

For one or more of the following: lightning and surge protection, reducing Electromagnetic interference, human safety Signup and view all the answers

What should be provided around building housing signalling equipment?

Perimeter Ring Earth Signup and view all the answers

Study Notes

Testing Instruments

Suitable instruments like Multi-meter, Volt meter, Ammeter, Ohmmeter, Frequency meter, Bell tester, Earth Tester, Earth leakage detector, Cable fault locator, Cable route tracer, Relay contact testing/cleaning kit, etc. should be used in the testing of electrical signalling circuits.
Calibration of these instruments should be checked periodically.

Physical Inspection of the Installation

Check that the work has been carried out in accordance with the approved plans and that equipment is of proper type and in good condition.
Check the following aspects during site inspections:
- Signals, location boxes and other outdoor equipment are as per approved plans and in good condition.
- Arrangements for proper ventilation, where provided, are not choked.
- Each location contains all the apparatus required as per approved plans, and the apparatus is of approved type.
- The location of insulation joint, jumper wiring, traction bonding in electrified areas, point machines, switch locks, and other apparatus is as per approved plans and their condition is satisfactory.
- The electrolyte, inter-connections between cells, cell voltage, etc. are in the required condition as per relevant specifications or instructions.
- Each wire is tagged or marked where feasible so that it can be identified at each end, and the nomenclature on the tag corresponds to that on the wiring diagram.

Earthing

Earthing shall be provided at the lever frame and other metallic frames of the cabin.
Earthing shall be provided at every location box where cables terminate.
Earthing shall be provided at each signal.
Wherever possible, the common earthing system shall be provided for closely located location boxes, signal posts, etc.
Separate earth is required for equipment requiring functional earth only.
Sheath & Armour of Main cables to be earthed. Armour of OFC shall be earthed at both ends.
In case of signals falling within 2 meters from the electrified track, the protection screen shall be connected to an earth.
There shall not be any possibility of simultaneous human contact with metallic bodies connected to different earths, where it is not possible to provide suitable spacing or partition between various metallic objects referred to above, they shall be connected to a common earth.
Common/Equi-potential earth for modern electronic equipment such as EI, DAC, Datalogger, etc. to be used in Relay room. Earth value shall not be more than one ohm and shall be measured annually during dry season.

Power Supply Arrangements

Power supply systems for Signalling Installations shall be as per Chapter 16.

System Integrity Testing (SIT)

System Integrity Testing (SIT) is a complete testing involving both Indoor & Outdoor signalling equipment for functional working & safety to be done in a new installation, at every interlocking alteration or periodically once in five years.
The signalling installation as a whole must be tested with detailed operational, functional and safety tests as per approved Control Table/Route Chart and Signalling & Interlocking Plan.

Precautions during Testing

Following precautions shall be taken during testing and checking so that:
- No signal taken 'OFF' for a train movement is thrown to 'ON' in the face of the train.
- No signal which will create a conflicting or unsafe movement is taken ‘OFF’.
- No point and isolation in a route set for a train movement is disturbed.
- No track relay of an occupied track circuit is energised.
- No voltage higher than permissible levels is applied to the equipment.
- There should be no risk of electric shock to testing or operating personnel.

Maintenance of Outdoor Signalling

Insulation tests on Cables shall be done as per Chapter 15 of SEM.
Cleanliness of LED Lenses: Polycarbonate Lenses of LED lamp shall be kept clean, and housing shall be kept clean and opening in inclement or stormy weather avoided.
Replacement of Defective LED lamps must be immediate, and new lamp shall be pre-tested as per approved instructions before putting into use.

Earthing for Outdoor Signalling Equipment

Earths are of two types: Functional Earth and Protective Earth.
Perimeter Ring Earth (PRE) shall be provided around building housing signalling equipment.
Chasis of all S&T equipment shall be bonded to BRC (Bonding Ring Conductor) provided inside the Power Equipment Room or Signal Equipment Room.
Earthing shall be provided as per approved specifications, drawings and code of practice issued by RDSO.
The maximum earth resistance shall be specified as per OEM & RDSO recommendations.
Earthing of cables, equipment, buildings, and structures is done for one or more of the following purposes: Lightning & surge protection of equipment, Earthing of metal screens of telecommunications cables and equipment for reducing Electromagnetic interference, and Human safety.

Installation of Signalling Equipment

Imperfect joints in soldering can be caused by a soldering iron that is not hot enough, not holding the iron on the connection for long enough, unclean terminals or wires, or using solder with an improper composition or fluxing agent.
Newly soldered connections should not be disturbed until the solder has cooled.

Wire Termination

When terminating wires, care should be taken to bend the wires in a clockwise direction.
Wire strippers should be used, and cutting pliers should not be used.
Washers and check nuts should be used when fastening.
No more than two wires should be terminated on one terminal.
Multi-strand wires should be terminated on terminal lugs and covered with insulation sleeves.
Crimping tools of appropriate design should be used, and proper soldering should be ensured.

Installation of Colour Light Signals

Colour Light Signals should be multi-unit and equipped with LED lamps.
The location and spacing of signals should be in accordance with approved plans and codal provisions.
The signal should be located to provide a clear view to the Loco pilot of an approaching train and should be as close to the track as possible.
The signal should have a minimum visibility as indicated in para 7.1.11.

Point Machines and Notches

Electric Point Machines should be provided with suitable gaskets, and wire entrances should be sealed to make them water-tight and dust-proof.
All extra openings should be closed as far as possible.
Locking: Electric Point Machine covers should be locked, and the cover provided for insertion of crank handle should also be locked with a separate key.
Notches in Stretcher Blades should not be tampered with or reconditioned. Worn-out slides should be replaced with new ones.

Testing of Relay Interlocking

Testing of Relay Interlocking involves operating point No. 2 to reverse position and clearing the signal route No. 2WBI by operating the signal switch/button.
The point should remain locked, and then the point knob should be restored to reverse.
De-energise 2RWKR, and signal 2WBI should go to 'ON'.
Restore the signal switch/button to normal, and when point No. 2 is free, shunt the track 2T.
Turn the point knob 2 from reverse to normal, and the point should remain locked.

Lubrication and Maintenance

All gearing and bearings should be properly lubricated according to manufacturer's instructions.
Commutators should be kept clean, smooth, and have a bright appearance.
Brushes should be kept clean and properly bedded on the commutator.
All cables and connections should be checked for intactness.
Adjustment of Contacts should be clean, free from pitting, and in proper adjustment.
Rain water drainage arrangements should be checked, especially prior to and during rainy season.
Fixing nuts and screws of newly installed point machine often tend to get loose, and care should be taken to attend to them and readjust where required.

Testing of Point Machine

Each sectional JE/SSE (signal) should test the point machine and do adjustments of the machine by conducting obstruction test as per para 19.3.6 & Annexure 19-MS2.

Maintenance of Electrical Point Detector (EPD)

Maintenance schedule as shown in Annexure: 19-MS3 should be followed.

Earthing for Outdoor Signalling Equipment

There are two types of earths: Functional Earth and Protective Earth.
Perimeter Ring Earth (PRE) should be provided around the building housing signalling equipment.
Chasis of all S&T equipment should be bonded to BRC (Bonding Ring Conductor) provided inside the Power Equipment Room or Signal Equipment Room.
Earthing should be provided as per approved specifications, drawings, and code of practice issued by RDSO.
The maximum earth resistance should be specified as per OEM & RDSO recommendations.
Earthing of cables, equipment, buildings, and structures is done for one or more of the following purposes: Lightning & surge protection of equipment, Earthing of metal screens of telecommunications cables and equipment for reducing Electromagnetic interference, and Human safety.

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This quiz covers the testing and inspection of electrical signaling circuits, including the use of various instruments and physical inspection of the installation.

Electrical Signaling Circuits Testing and Inspection

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Questions and Answers

What is the purpose of calibration of testing instruments?

What should be checked during physical inspection of the installation?

What is the purpose of tagging or marking wires?

What should be checked in terms of ventilation during site inspections?

What type of instruments are suitable for testing electrical signalling circuits?

Where should earthing be provided for signal equipment?

What should be checked in terms of the location of apparatus during site inspections?

What is the special case where armouring of unscreened cables needs to be earthed?

What should be checked in terms of electrolyte and inter-connections during site inspections?

Why is common earthing not allowed in certain cases?

What is the purpose of checking the signals, location boxes, and other outdoor equipment during site inspections?

What is the recommended color for earth wires for quick identification?

What is the maximum earth value required for modern electronic equipment?

How often should the earth value be measured?

Why should earth wires be kept as straight as possible?

What should be done when it is not possible to provide suitable spacing or partition between metallic objects?

What is the purpose of grouping location boxes in a large yard area?

What is the recommended frequency for System Integrity Testing (SIT) in a signalling installation?

What is the purpose of a separate pair of conductors for each direction in a large yard area?

What is the primary concern during System Integrity Testing (SIT)?

Why is it essential to plan System Integrity Testing (SIT) carefully?

What is the purpose of providing telephone communication in the RE area?

What is the recommended duration for non-interlocking/disconnection during System Integrity Testing (SIT)?

What is the basis for planning System Integrity Testing (SIT)?

What is the primary concern during signal testing and checking?

Why should the housing of LED lamp units be kept clean?

What should be checked periodically on LED lamps?

Why must defective LED lamps be replaced immediately?

What is essential for electric point machines?

What should be avoided during testing and checking?

What is the purpose of insulation tests on cables?

What is the primary consideration when replacing LED lamps?

What is the primary function of a Functional Earth in signalling equipment?

What is the purpose of bonding the chassis of S&T equipment to BRC?

What is the recommended practice for earthing of signal equipment?

What is the maximum earth resistance specified for signal equipment?

What is the purpose of providing a Perimeter Ring Earth (PRE) around a building housing signalling equipment?

What is the primary purpose of earthing in signalling equipment?

What is the purpose of connecting the chassis of S&T equipment to MEEB?

What is the primary purpose of earthing in terms of human safety?

What is the primary reason for avoiding imperfect joints in signalling equipment?

What should be used to strip wire insulation during wire termination?

Why should multi-strand wires be terminated on terminal lugs and covered with insulation sleeves?

What is the minimum visibility requirement for colour light signals?

What type of lamps should be used in colour light signals?

What is the primary consideration when locating colour light signals?

What should be used to bend wires during wire termination?

What type of training should railway conduct?

What is the purpose of the 120-second time delay in the relay interlocking system?

What happens when point No. 2 is operated to the reverse position?

What should be done after operating point knob 2 to normal?

What is the purpose of controlling point No. 2 to the reverse position?

What happens when the point knob 2 is turned from reverse to normal?

Why is it necessary to operate the signal switch/button to normal?

What is the purpose of de-energizing 2RWKR?

What is the consequence of not operating point No. 2 to the reverse position?

Why is it essential to keep the commutator clean and smooth?

What is the purpose of checking the fixation nuts and screws of newly installed point machines?

What is the recommended frequency for testing and maintaining electrical point detectors (EPD)?

Why is it essential to check the tail cables of point machines?

What is the purpose of conducting obstruction tests on point machines?

Why should emery paper not be used to clean the commutator?

What should be checked during maintenance of point machines?

Why is it essential to check the rainwater drainage arrangements before the rainy season?

What is the purpose of dividing points in the yard into convenient groups?

What should be done to avoid rodent entry and water ingress?

What should be sealed to make them water tight and dust proof?

What should be locked to provide access only for crank handle and crank handle key?

What should not be tampered or reconditioned?

What should be replaced with new ones when worn out?

What is the purpose of using NX key of different wards?

What type of earth is used to conduct current through earth during normal operation of equipment?

Why should the crank handles be normally locked?

Where should the chassis of all S&T equipment be bonded to?

What is the purpose of providing a Perimeter Ring Earth (PRE) around a building housing signalling equipment?

What should be specified as per OEM and RDSO recommendations?