Indian Railways Telecom: Periodic Tests

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Questions and Answers

What is the frequency for measuring the transmission loss of control circuits?

Once every year

What is the acceptable disparity between each limb of the loop resistance?

5% of normal calculated value

How often should the protection path for Control Circuits of BSNL/RAILTEL be checked?

Daily

What is the purpose of retesting a circuit after rectifying defects?

To verify the rectification of defects Signup and view all the answers

What is the frequency for joint testing of Long Haul network protection path with NOC (Railtel)?

Once every 3 months Signup and view all the answers

What is the range of output from the audio oscillator used in testing control circuits?

-10 dB to +10 dB Signup and view all the answers

Where should the results of periodic tests be recorded?

Both a and b Signup and view all the answers

What is the purpose of checking the voice logger during periodic tests?

To ensure the voice logger is recording channels correctly Signup and view all the answers

Who is responsible for forwarding one copy of the line interruption and failure report to the PCSTE?

DSTE/Sr.DSTE Signup and view all the answers

What is the formula to calculate the efficiency of line operation?

A-B / A x 100 Signup and view all the answers

What is the purpose of maintaining a record of control interruptions?

To track the total number of interruptions and their duration Signup and view all the answers

What is the frequency tolerance for DTMF frequencies?

± 1.5% Signup and view all the answers

What is the purpose of submitting a monthly line interruption and failure report?

To inform the Sr.Divisional Signal & Telecommunication Engineer of the line interruptions and failures Signup and view all the answers

Who is responsible for preparing the monthly line interruption and failure report?

Not specified in the content Signup and view all the answers

What is the purpose of calculating the MTTR and MTBF?

To track the performance of the telecom equipment Signup and view all the answers

What is the purpose of maintaining a record of periodical test reports?

To track the performance of the telecom equipment Signup and view all the answers

What is the primary function of the test panel in a control office?

To facilitate independent testing of control circuits Signup and view all the answers

What is the purpose of the 100 volt megger in telecom equipment maintenance?

To test the insulation of internal wiring and external lines Signup and view all the answers

What is the primary benefit of having a NMS along with associated equipment in a telecom control room?

To provide ease of operation, testing, and management Signup and view all the answers

What is the purpose of the LED indication on the telephone?

To indicate when the handset is lifted off the cradle Signup and view all the answers

What is the primary function of the standard line test oscillator with a dB meter?

To carry out measurement of line transmission loss and equipment insertion loss Signup and view all the answers

What is the purpose of cleaning and properly terminating wires on the terminals on the rosette and CT box?

To ensure the integrity of the electrical connections Signup and view all the answers

What is the primary benefit of having a universal calling device in a control office?

To provide a means of calling any station on any circuit Signup and view all the answers

What is the purpose of inspecting the telephone cord and its connection?

To ensure the telephone cord is in good condition and properly connected Signup and view all the answers

What is the primary purpose of Railway Control Circuits in train operation?

To facilitate efficient communication between controller and way-side stations Signup and view all the answers

What type of control system is provided for communication between the Deputy Controller and important stations?

Deputy Control Signup and view all the answers

What is the function of Voice Data Logger/ Monitor in Railway Control Circuits?

To record and analyze communication data Signup and view all the answers

What is the primary purpose of Traction Power Control in Railway Control Circuits?

To maintain and control the OHE system Signup and view all the answers

What is the function of Remote Control for SCADA in Railway Control Circuits?

To acquire and analyze data for OHE system maintenance Signup and view all the answers

What is the primary purpose of Section Control / Train Control in Railway Control Circuits?

To facilitate efficient communication for train operation and effective utilization of section capacity Signup and view all the answers

What is the key benefit of using Railway Control Circuits in train operation?

Enhanced communication and reliability Signup and view all the answers

What is the importance of Voice Data Logger/ Monitor in ensuring efficient train operation?

It ensures reliable and efficient communication between controllers and way-side stations Signup and view all the answers

Where should equipment producing noise during operation be located?

In a different room outside the control office Signup and view all the answers

What is the primary purpose of having a test room close to the control office?

To enable the test room staff to attend to any fault promptly Signup and view all the answers

What should be considered while planning a control office?

Space required for future additions and alterations Signup and view all the answers

Why should separate conduits or runways be provided for communication and high voltage electric wires?

To prevent damage to the communication wires Signup and view all the answers

What should be included in the building specifications for a control office?

Distributing systems for communication wires and high voltage electric wires Signup and view all the answers

What is the purpose of providing mechanical protection for cables and wires?

To achieve trouble-free service Signup and view all the answers

Where should batteries, especially secondary cells, be located?

In a separate room outside the control office Signup and view all the answers

What should be earmarked in the control office design?

Space for equipment and stationery and filing cases Signup and view all the answers

Study Notes

Periodic Tests

Control circuits should be periodically tested by the inspector in charge to check the condition of:
- Inside wiring in control offices and way-stations
- External line and cables
- Control office and wayside station equipment
Voice logger should be checked periodically for working of channels and recording
Circuits transmission loss should be measured once every year
Line loop resistance should be measured once every year, with a tolerance of 5% of normal calculated value
Results of tests should be entered in a register maintained separately at each sectional inspector's headquarters and in the office of DSTE/Sr.DSTE
Any defects noticed during tests should be rectified on the spot and the circuit retested before proceeding with further tests

Testing of Control Circuits

A test panel of approved type should be installed in all control offices for the use of the maintenance staff to facilitate:
- Disconnection of control office equipment for independent testing
- Patching facilities for substitution by radio patch, of deputy control or spare lines to restore communication on interrupted circuits
- Monitoring of all circuits without interruption to normal working
- Provision for a universal calling device to call any station on any circuit
- Provision for calling attention of the maintenance staff by the controllers
A standard line test oscillator with a dB meter should be provided to carry out measurement of line transmission loss and equipment insertion loss
A 100 volt megger should be provided to carry out insulation tests on internal wiring and external lines

Railway Control Circuits

Railway Control Circuits are omnibus telephone circuits that provide communication with each train working point, facilitating efficient train operation
They should provide satisfactory and reliable communication between the controller and various way-side stations, important signal cabins, loco sheds, and yard offices
Provision of Voice Data Logger/Monitor for Control Circuits is required

Control Systems

According to traffic requirements, a section may be provided with one or more Railway Control Circuits, including:
- Section Control/Train Control: for communication between the Section/Train Controller and way-side stations, junction station, block cabins, loco sheds, and yards in a division
- Deputy Control: for communication between the Deputy Controller and important stations, junctions, terminal stations, yard master's offices, loco sheds, and important signal cabins in a division
- Traction Power Control: for communication between the traction power controller and SM's Office, FPs/SPs/SSPs for maintenance of OHE system
- Remote Control for Supervisory Control and Data Acquisition System (SCADA): for remote control of OHE energization/de-energization and various data acquisition

DTMF Frequency

Standard DTMF frequency is:
- Low Group: 697 Hz, 770 Hz, 852 Hz, 941 Hz
- High Group: 1209 Hz, 1336 Hz, 1447 Hz, 1633 Hz
- Frequency tolerance: ± 1.5%
Frequencies are used for group calling, long ring, general call, reset, cancel, and last code repeat

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