Electronics Installation and Safety Standards

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Questions and Answers

What is the required resistance of the earthing system for instruments?

Less than 5 ohms

Less than 10 ohms (correct)

Less than 20 ohms

Less than 15 ohms

What is the minimum diameter required for the earth wire?

4 mm (correct)

6 mm

2 mm

8 mm

How far must a separate earth for an instrument be buried below ground?

2.5 meters

1 meter

2 meters

1.5 meters (correct)

What is a key condition for the installation of Token instruments?

The token from one section cannot be placed in another instrument at that station Signup and view all the answers

Which type of instrument does not require a separate earth?

Block instruments with metallic return Signup and view all the answers

What must be ensured about the movement of mechanical parts in instruments after installation?

They must be free to move without undue friction Signup and view all the answers

What must not be present in the earth wire during installation?

Sharp bends or spirals Signup and view all the answers

What configurations should consecutive block sections be provided with?

A, B & C Signup and view all the answers

What is the minimum total pick up time for relays used in block instruments?

300 msec Signup and view all the answers

Which condition must be satisfied for the shunting key to be removed?

In 'Line Closed' or 'Train Going To' condition Signup and view all the answers

What prevents the Last Stop Signal from being taken 'OFF'?

When the commutator is in any position other than 'Line Clear' Signup and view all the answers

When is the Last Stop Signal automatically replaced to 'ON'?

When the train enters the block section Signup and view all the answers

What type of relay should not be used for stick circuits of the block instrument?

Quick acting relays Signup and view all the answers

What is the minimum insulation resistance value required between individual insulated circuits and Earth for block instruments?

10 mega ohms Signup and view all the answers

What must be checked before the 'Train on Line' indication appears?

The commutator handle must be locked Signup and view all the answers

Which of the following is NOT a requirement for the installation of single line tokenless block instruments?

Must have complex access for maintenance Signup and view all the answers

What condition must be met for the Last Stop Signal at the sending station to be taken 'OFF'?

The receiving station instrument should be set to 'Train Coming From' condition. Signup and view all the answers

Which of the following is NOT recorded in the register of block instruments maintained by the Senior Section Engineer?

Operational issues encountered Signup and view all the answers

What operation is required for block release in the system?

Operation of two track circuits sequentially Signup and view all the answers

Which of these checks should be conducted during the installation of block instruments?

All nuts and bolts should be secure and complete. Signup and view all the answers

How is block release achieved in a single line tokenless block instrument?

By the operation of two track circuits sequentially. Signup and view all the answers

What will happen to the Last Stop Signal when a train enters the block section?

It will be maintained in the 'ON' position until conditions return to safe. Signup and view all the answers

Which observation is required for the Front Panel of Push Button type instruments during installation?

It should be free from splitting, twisting, or warping. Signup and view all the answers

What should be done before measuring insulation resistance to block instruments?

Remove all external connections to the block instrument. Signup and view all the answers

What document must technicians use to keep track of token balances?

Token Balance Book Signup and view all the answers

Which personnel are required to sign the Token Balance Book when tokens are extracted?

Both Station Masters involved Signup and view all the answers

Under what condition can tokens be extracted or replenished in the instruments?

When the instruments are in the 'Line Closed' position Signup and view all the answers

What is the minimum token balance that triggers a warning message to the technician?

Six tokens Signup and view all the answers

What must each sectional JE/SSE (Signal) do regarding the census of tokens?

Take a census of tokens at least once in six months. Signup and view all the answers

Who is responsible for the safe operation of the token instruments?

The Technician operating the instruments Signup and view all the answers

What is required from the Traffic Department regarding token pouches?

Damaged pouches should not be used Signup and view all the answers

What action should be taken for damaged tokens?

They should be removed, broken up, and returned to Stores. Signup and view all the answers

What is recorded on Card No. S&T/TL regarding lost tokens?

Particulars of lost tokens. Signup and view all the answers

What must technicians do to ensure the locks on instruments are secure?

Conduct fortnightly inspections Signup and view all the answers

What happens when a token is lost and not found after a thorough search?

A joint certificate is issued and a circular is sent out. Signup and view all the answers

Which of the following statements is true regarding bell signals in operations?

Authorized code of bell signals is still necessary Signup and view all the answers

When a lost token is replaced, what should be considered?

The new token should be the next higher number in the series. Signup and view all the answers

What should be done with the found lost token after it has been replaced?

It should be broken and returned to stores. Signup and view all the answers

How often should the record of tokens be updated in the Signal History Book?

Every six months. Signup and view all the answers

What must supervisors do when a token is lost?

Prepare a joint certificate for higher authorities. Signup and view all the answers

Study Notes

Earthing

Separate earth provided for each instrument
Earth buried at least 1.5 meters deep
Earth at least 2.5 meters from other earths
Earth resistance not more than 10 ohms
Separate earth for equipment using earth return
Earth wire length as short as possible
Earth wire diameter at least 4mm
Earth wire protected from damage
Connections well soldered

Installation of Single Line Token Instruments

Token placement prevents one section token from use in another instrument at a station
Ideal installation prevents token from being placed in a subsequent station in the event of an overrun
Consecutive sections use configurations A, B, and C, followed by repeating those configurations
Junction or new crossing stations use configurations D and E
Instruments mounted level (using spirit level, if needed)
Prevent tokens from tilting or entering incorrect races (specifically for ball and tablet forms of token instruments)

Tests After Installation and Before Commissioning

Check connections at both ends
Check all moving parts for friction or jamming
Ensure commutator changes only when token engages corresponding tracks (for ball and tablet instruments)
Check insulation and absence of instrument body/earth leakage on wiring and components

Installation of Single Line Tokenless Block Instruments

Instruments mounted level for easy maintenance access
Thorough pre-installation check for mechanical damage, corrosion, and secure components (nuts and bolts)
Ensure that the front panel (Push Button type instruments, specifically) is free from damage (splitting, warping, etc.)
Check that relays and counters are intact, sealed properly
Measure insulation resistance between each circuit and earth; minimum 10 mega-ohms
Block release sequence controlled by two track circuits

Testing Single Line Tokenless Block Instruments

Last Stop Signal at sending station prevents being turned 'OFF' until receiving station is set for "Train Coming From" and sending station set for "Train Going To" situations
Line Clear granted only when signals and Last Stop Signal show 'ON'
Last Stop Signal remains 'ON' until train clears the block section, then returns to 'Line Closed' and a new 'Line Clear' is issued
Opposing signals can't both be turned 'OFF' at the same time
Train arrival confirmation is directional
Shunting key operation only allowed in "Line Closed" or "Train Going To" conditions

Installation of Double Line Block Instruments

Quick acting relays not used in stick circuits (specific type of Q relays required, with minimum 300-msec pick-up time)
DC 3-position polarized relays, approved type, used for line circuits in block working
Block release sequential, using two track circuits

Installation Tests for Double Line Instruments

Commutator needs to be locked, "Train on Line" indication should appear during the commutator movement from "Line Clear" to "Traon on Line"
Block Clearance Relay should activate only after commutator changeover.
Last Stop signal 'turn OFF' function restricted if commutator not on "Line Clear"
Last Stop signal automatically turns 'ON' for trains passing through a block section, remaining 'ON' until "Line Clear" condition achieved.
Commutator movement from "Line Closed" to "Train On Line" allows a return to "Line Closed"

Token Instrument Maintenance - General

Senior Section Engineer maintains a register of instruments with type, serial number, location, and manufacturer details.
Register includes installation and last overhaul dates
Record of tokens in or out of service, including lost or damaged devices
Sectional JE/SSE performs a census of tokens every 6 months, recording their status and location for safety and proper management.

Damaged Tokens

Damaged tokens are replaced by tokens of the same number, and maintenance personnel must be informed
Cracked or deformed tokens, as well as those smaller than standard size, must be removed from service and sent to the Stores
Maintain records of removed tokens

Lost Tokens

Senior staff issues a joint certificate if a token is lost for thorough search, initiating procedures, canceling the lost token, and advising staff in the case that a token has gone missing.
Missing tokens remain inactive
Six months without finding loss token, create a replacement
Lost tokens, even when located later, are broken and stored

Balancing of Tokens

Technicians transfer tokens between instruments (when necessary)
Token Balance Book (form S&T/TB) used to record these transgers
This form is checked by senior personnel
Confirmation of the token balance transfer with relevant staff (station master) at both ends for verification and consistency.

Responsibility of Operating Staff

Staff responsible for safe equipment operation utilizing the correct signal codes.
Proper sequence and use of signals imperative.
Bell signals still important, even if other forms of communication exist.

Block Instruments and Ancillary Maintenance

Fortnightly inspections ensure proper component function (locks, indicators, contacts, springs, armatures, wiring, terminal screws)
Circuits and associated wiring, as well as electrical components, should be routinely inspected for proper function.
Indicators and contacts need to be free from pitting and must be operational when triggered.

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Description

This quiz covers essential standards for earthing separate to each instrument, including specifications for earth depth, resistance, and wire regulations. Additionally, it addresses the installation protocols for single line token instruments, focusing on token placement and configuration requirements. Test your knowledge on these critical safety and installation practices.