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Questions and Answers
What is the minimum input signal level to the amplifier?
What is the maximum output level of the amplifier to avoid overloading?
What is the primary purpose of the Remote Monitoring facility?
What is the frequency range for measuring the cross-talk level of the amplifier?
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What happens when the AC fuse fails?
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What is the maximum harmonic distortion allowed at 1 KHz when the amplifier gain is set to its maximum?
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What is the purpose of authorizing command codes through suitable codes/passwords/keys?
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What is the nominal operating voltage of the power supply unit of the amplifier-equalizer equipment?
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What is the purpose of earthing non-current carrying metal parts of amplifier/equalizer equipment?
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What is the minimum voltage variation allowed for the power supply unit?
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What is the purpose of the charge controller in the power supply unit?
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What function can be executed using the remote monitoring facility?
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What is the benefit of providing remote monitoring facility separately for sectional control, deputy control, and S&T control circuits?
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What is the purpose of duplicating the power supply unit, including batteries?
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What is displayed on the equipment in addition to being displayed at the control desk in the test room?
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What is the purpose of facility of conference among the subscribers?
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What is the frequency of checking the power supply voltage at the input point for the Repeater/Amplifier-Equaliser equipment?
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Who is responsible for section-wise and end-to-end line up of all circuits in the Repeater/Amplifier-Equaliser equipment?
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What is the purpose of checking the functioning of all circuits in the Repeater/Amplifier-Equaliser equipment?
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How often should the Junior Engineer perform section-wise and end-to-end line up of all circuits in the Repeater/Amplifier-Equaliser equipment?
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What is the role of the Telecom Technician in the maintenance of the Repeater/Amplifier-Equaliser equipment?
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How often should the Sr. Section Engineer perform checking of various cards in proper position in the Repeater/Amplifier-Equaliser equipment?
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What is the purpose of checking the power supply voltage at the input point in the Repeater/Amplifier-Equaliser equipment?
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Who is responsible for checking the functioning of all the circuits in the Repeater/Amplifier-Equaliser equipment?
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What is the interval for checking and tightening of all connections in batteries?
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What is the frequency for measuring voltages and gravity in batteries?
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What is the interval for cleaning and tightening of all connections in earthing?
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What is the frequency for measuring earth resistance in earthing?
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Which of the following is not a quarterly maintenance task for batteries?
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What is the interval for checking and tightening of all connections in batteries during installation?
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Which of the following is a weekly maintenance task for batteries?
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What is the interval for measuring earth resistance in earthing during installation?
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What type of cables are being laid on important routes of Indian Railways?
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What is the purpose of P.D.MUX equipment at every station?
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What happens when Amplifier-Equaliser system is used?
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What is the facility of end/mid station patching working used for?
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What is the purpose of the 'U’ Link Panel?
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What is the nominal gain of the VF Amplifier?
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What is the input impedance of the VF Amplifier?
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Where is the control communication provided on non-important non-electrified routes?
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What type of cables are being laid on non-important non-electrified routes of Indian Railways?
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Where is the control communication provided on OFC cable?
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What is the purpose of Amplifier-Equaliser equipment in control communication?
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What is the nominal gain of the VF Amplifier?
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What is the input impedance of the VF Amplifier?
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What is the facility of end/mid station patching working used for?
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What is the purpose of 'U’ Link Panel?
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What is the purpose of Decoder and other PCBs?
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What is the minimum input signal level required for the amplifier to produce an output of 0 dBm?
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What is the purpose of having a facility for solar power operation in the power supply unit of Amplifier-Equaliser equipment?
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What is the maximum permissible cross talk level across the amplifiers meant for same quad and adjacent quad?
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What is the purpose of having a variable slope in the equaliser response?
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What happens if the output of the amplifier exceeds +4 dBm?
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Why is it necessary to duplicate the power supply unit including batteries?
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What is the frequency range within which the frequency response of the amplifier must be flat within ±3 dB?
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What is the maximum permissible harmonic distortion at 1 KHz when the amplifier gain is set to its maximum?
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What is the purpose of providing remote monitoring facility separately for sectional control, deputy control, and S&T control circuits?
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What happens when the AC fuse fails in remote monitoring facility?
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Why is it desirable to have disabling and enabling of command codes through suitable authorization code/password or key?
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What is earthed in amplifier/equalizer equipment?
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What can be executed using the remote monitoring facility?
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What is displayed on the equipment in addition to being displayed at the control desk in the test room?
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What is the purpose of facility of conference among the subscribers?
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What is the benefit of providing a separate remote monitoring facility for each type of circuit?
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What type of short-circuit protection should be provided in the power supply unit?
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What should happen to the way station equipment when the battery voltage drops to a threshold voltage?
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What is the minimum capacity of each low maintenance battery in the separate housing?
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How many subscribers can be connected to the intercom facility?
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What is the maximum loop resistance up to which the intercom telephones can be extended?
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How can the controller call a subscriber using the intercom facility?
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What can be done to prevent a subscriber from calling the controller?
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What is the purpose of the intercom facility in the way station equipment?
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What is the interval for checking and tightening of all connections in batteries?
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What is the frequency for measuring voltages and gravity in batteries?
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What is the interval for cleaning and tightening of all connections in earthing?
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What is the frequency for measuring earth resistance in earthing?
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What is the purpose of checking and tightening of all connections in batteries?
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What is the purpose of measuring earth resistance in earthing?
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What is the benefit of regular maintenance for batteries?
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What is the purpose of earthing in control communication systems?
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Study Notes
Quad Cable Based Control Communication System
- In electrified and non-electrified sections of Indian Railways, OFC cable and six quad jelly filled cables are being laid on important routes, while on non-important non-electrified routes, only quad cables are being laid.
- Control communication is provided on OFC by providing STM-1/IP-MPLS router and P.D.MUX equipment at every station.
- Block circuits, emergency sockets, and level crossing gate communication are provided on quad cable.
- Wherever OFC cable work is not completed yet and only quad cable is laid, control as well as block communication are provided on the quad cable itself.
System of Working of Control Circuits using Amplifier-Equaliser System
- The Amplifier-Equaliser system does not require quad cable loading.
- Every station is provided with Amplifier-Equaliser equipment to provide communication and equalize losses in the VF band.
- The equipment is provided with the facility for end/mid station patching working in case of cable or equipment failure without reversing the direction of amplifiers.
- The system comprises of the following assemblies and is suitable for mounting on a 19-inch rack:
- Cable termination, distribution, and monitoring panel
- `U’ Link Panel
- Equaliser Amplifier and VF Transformer panel
- Decoder and other PCBs
Electrical Parameters
- Input impedance of VF Amplifier is 470 Ohm ±10%.
- Nominal gain of the amplifier is 20 dB ±1 dB when measured at a frequency of 1 KHz.
- Frequency response of the amplifier is flat within ±3 dB in the frequency range of 300 Hz to 3.4 KHz.
- Signal at input may be at (-)20 dBm (minimum) and the output in this case shall be 0 dBm with amplifier gain at maximum.
- Upper limit of input signal is determined by overload point, so that the output does not exceed +4 dBm without need arising for adjusting the gain of the amplifier.
- Amplifier shall not be overloaded beyond an output of +4 dBm.
- Cross-talk level of the equipment when measured after termination point is better than –60 dB, across the amplifiers meant for same quad and adjacent quad.
- Frequency for the measurement for cross-talk is 1 KHz.
- Equaliser response has a variable slope from 0 dB to 12 dB at least in the frequency range of 300 Hz to 3.4 KHz.
- Harmonic distortion at 1 KHz shall not exceed 3% when the gain of the amplifier is set to its maximum and output is properly loaded.
Power Supply Requirement
- Power supply unit of Amplifier-Equaliser equipment operates at 230V AC nominal with variation from 160 V to 270 V.
- It has a facility for Solar Power operation with an arrangement of automatic change over from 230V AC to Solar Supply and vice versa.
- The power supply unit is fully duplicated, including batteries with suitable overvoltage protection (above 270 V).
Remote Monitoring Facility
- Remote Monitoring facility is provided for remote monitoring and fault localization from the test room.
- Remote Monitoring facility for Sectional Control, Deputy Control, and S&T Control Circuits is separately provided.
- It is possible to execute the following functions using remote monitoring facility:
- Disconnect one side of the Card of that Circuit at a particular station.
- Disconnect another side of the Card of that Circuit at a particular station.
- Buffer 1 cut for the Card of that Circuit at a particular station.
- Buffer 2 cut for the Card of that circuit at a particular station.
- Battery change over.
- Connect Cards of that Circuit at a particular station.
- Monitor Power Supply Voltage.
- Monitor AC fuse, battery charging status.
Earthing
- All non-current carrying metal parts of amplifier/equaliser equipment, including armour and sheath of quad cable, are bonded together and earthed.
Maintenance Schedule
- Repeater/Amplifier-Equaliser equipment:
- Weekly: Checking of Power Supply voltage at the input point.
- Monthly: Checking of various cards in proper position.
- Quarterly: Checking the functioning of all the circuits.
- Batteries:
- Weekly: Cleaning and tightening of all connections.
- Monthly: Measurement of voltages and gravity.
- Quarterly: Verification of the above.
- Earthing:
- 3 Monthly: Cleaning and tightening of all connections.
- 6 Monthly: Measurement of earth resistance.
- Yearly: Verification of the above.
Quad Cable Based Control Communication System
- In Indian Railways, OFC cables and six quad jelly-filled cables are laid in important routes, while only quad cables are laid in non-important non-electrified routes.
System of Working of Control Circuits using Amplifier-Equaliser System
- Wherever Amplifier-Equaliser system is used, quad cable is not required to be loaded.
- Every station shall be provided with Amplifier-Equaliser equipment to provide communication and equalize losses in the VF band.
- The equipment shall have the facility for end/mid station patching working in case of cable or equipment failure without reversing the direction of amplifiers.
- The complete system comprises of:
- Cable termination, distribution, and monitoring panel
- `U’ Link Panel
- Equaliser Amplifier and VF Transformer panel
- Decoder and other PCBs
Electrical Parameters of Amplifier
- Input impedance of VF Amplifier: 470 Ohm ±10%
- Nominal gain of the amplifier: 20 dB ±1 dB at a frequency of 1 KHz
- Frequency response of the amplifier: flat within ±3 dB in the frequency range of 300 Hz to 3.4 KHz
- Signal at input: (-)20 dBm (minimum) and output: 0 dBm with amplifier gain at maximum
- Upper limit of input signal is determined by overload point, so that the output does not exceed +4 dBm
- The amplifier shall not be overloaded beyond an output of +4 dBm
- Cross-talk level of the equipment: better than –60 dB, across the amplifiers meant for same quad and adjacent quad
- Harmonic distortion at 1 KHz: not exceed 3% when the gain of the amplifier is set to its maximum and output is properly loaded
- Equaliser response: variable slope from 0 dB to 12 dB at least in the frequency range of 300 Hz to 3.4 KHz
Power Supply Requirement
- Power supply unit of Amplifier-Equaliser equipment operates at 230V AC nominal with variation from 160 V to 270 V
- Facility for Solar Power operation with arrangement of automatic changeover from 230V AC to Solar Supply and vice versa
- The power supply unit shall be fully duplicated including batteries with suitable overvoltage protection
- Short-circuit protection of self-restoring type
- It shall be possible to by-pass automatically the way station equipment in case the battery voltage drops to threshold voltage
- A set of two low maintenance batteries of 12V each, capable of operating the equipment for 72 hours at least
Intercom Facility
- In addition to Omnibus circuits to be provided at each station, 8-way intercom shall be provided with facility for dialling any of the subscribers by the controller
- Separate Cards shall be provided for 8-way intercom in the way station equipment
- It shall be possible to extend these telephones up to loop resistance of 300 Ohms
- Intercom circuit shall be so designed that all the subscribers can talk to each other without disturbing the controller
- It shall be possible to call any subscriber within the group using suitable access codes
- The controller shall be able to call any of the subscribers using DTMF code
- Facility of conference among the subscribers shall be provided
- There shall be facility to bar any telephone from calling the controller
Remote Monitoring Facility
- Remote Monitoring facility shall be provided for remote monitoring and fault localization from test room
- It shall be possible to execute the following functions using remote monitoring facility:
- Disconnect one side of the Card of that Circuit at a particular station
- Disconnect another side of the Card of that Circuit at a particular station
- Buffer 1 cut for the Card of that Circuit at a particular station
- Buffer 2 cut for the Card of that circuit at a particular station
- Battery changeover
- Connect Cards of that Circuit at a particular station
- Monitor Power Supply Voltage
- Monitor AC fuse, battery charging status
- On failure of AC fuse, remote Card automatically sends fuse fail signal to Test Room Equipment along with its identity code
- Disabling and enabling of Command Codes through suitable authorization Code/Password or Key shall be desirable to prevent any unauthorized initiation
Earthing
- All non-current carrying metal parts of amplifier/equaliser equipment including armour and sheath of quad cable shall be bonded together and earthed
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Description
This quiz covers the use of quad cables and OFC cables in electrified and non-electrified sections of Indian Railways for control communication systems.
