Quad Cable Based Control Communication System PDF

CHAPTER X QUAD CABLE BASED CONTROL COMMUNICATION SYSTEM 10.1 SYSTEM: In electrified as well as non-electrified sections of Indian Railways, on important routes, OFC cable as well as six quad jelly filled cables are being...

CHAPTER X QUAD CABLE BASED CONTROL COMMUNICATION SYSTEM 10.1 SYSTEM: In electrified as well as non-electrified sections of Indian Railways, on important routes, OFC cable as well as six quad jelly filled cables are being laid, but on non-important non-electrified routes, only quad cables are being laid. Wherever OFC and quad cables are 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. 10.2 SYSTEM OF WORKING OF CONTROL CIRCUITS USING AMPLIFIER- EQUALISER SYSTEM: 10.2.1 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 at that station and to equalize the losses in the VF band. 10.2.3 The equipment shall be provided with the facility for end/mid station patching working in case of cable or equipment failure without reversing the direction of amplifiers. 10.2.4 The complete system shall comprise of the following assemblies and shall be suitable for mounting on a 19 inch rack; a) Cable termination, distribution and monitoring panel. b) `U’ Link Panel. c) Equaliser Amplifier and VF Transformer panel. d) Decoder and other PCBs. 10.2.5 ELECTRICAL PARAMETERS: a) Input impendence of VF Amplifier shall be 470 Ohm ±10%. b) The nominal gain of the amplifier shall be 20 dB ±1 dB when measured at a frequency of 1 KHz. c) The frequency response of the amplifier shall be flat within ±3 dB in the frequency range of 300 Hz to 3.4 KHz. d) The signal at input may be at (-)20 dBm (minimum) and the output in this case shall be 0 dBm with amplifier gain at Indian Railways Telecom Manual - 2021 Page 103  maximum. The upper limit of input signal is determined by overload point, so that the output does not exceed +4 dBmwithout need arising for adjusting the gain of the amplifier. e) The amplifier shall not be overloaded beyond an output of +4 dBm f) Cross talk level of the equipment when measured after termination point shall be better than –60 dB, across the amplifiers meant for same quad and adjacent quad. Frequency for the measurement for cross talk shall be 1 KHz. g) The Equaliser response shall have variable slope from 0 dB to 12 dB at least in the frequency range of 300 Hz to 3.4 KHz. h) 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. 10.2.6 POWER SUPPLY REQUIREMENT: 10.2.6.1 The power supply unit of Amplifier-Equaliser equipment shall normally operate at 230V AC nominal with variation from 160 V to 270 V. It should also have facility for Solar Power operation with arrangement of automatic change over from 230V AC to Solar Supply and vice versa. The charge controller for use with Solar Panel shall be provided as part of the power supply unit. 10.2.6.2 The power supply unit shall be fully duplicated including batteries with suitable over voltage protection (above 270 V). 10.2.6.3 The power supply unit shall be provided with short-circuit protection of self restoring type. 10.2.6.4 It shall be possible to by-pass automatically the way station equipment in case the battery voltage drops to threshold voltage of the amplifier to be defined by the manufacturer as per requirement of design. 10.2.6.5 A set of two low maintenance batteries of 12V each, capable of operating the equipment for 72 hours at least, shall be kept in a separate housing made of unbreakable material. The capacity of the each of the battery shall be minimum 40AH. 10.2.7 INTERCOM FACILITY: 10.2.7.1 In addition to Omnibus circuits to be provided at each station, 8-way intercom shall be provided with facility for dialing any of the subscribers by the controller. 10.2.7.2 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. Indian Railways Telecom Manual - 2021 Page 104 10.2.7.3 Intercom circuit shall be so designed that all the subscribers can talk to each other without disturbing the controller. 10.2.7.4 It shall be possible to call any subscriber within the group using suitable access codes. 10.2.7.5 The controller shall be able to call any of the subscribers using DTMF code and whenever the controller calls it, it gets disconnected from other telephones. Even when a subscriber’s telephone is off-hook, it shall be possible for controller to call the subscriber and talk. 10.2.7.6 The subscriber shall also be in a position to call controller by dialing suitable access code. 10.2.7.7 There shall be facility to bar any telephone from calling the controller. 10.2.7.8 Facility of conference among the subscribers shall be provided. 10.2.8 REMOTE MONITORING FACILITY: 10.2.8.1 Remote Monitoring facility shall be provided for remote monitoring and fault localization from test room. Remote Monitoring facility for Sectional Control, Deputy Control and S&T Control Circuits shall be separately provided. 10.2.8.2 It shall be possible to execute the following functions using remote monitoring facility; i) Disconnect one side of the Card of that Circuit at a particular station. ii) Disconnect another side of the Card of that Circuit at a particular station. iii) Buffer 1 cut for the Card of that Circuit at a particular station. iv) Buffer 2 cut for the Card of that circuit at a particular station. v) Battery change over. vi) Connect Cards of that Circuit at a particular station. vii) Monitor Power Supply Voltage. viii) Monitor AC fuse, battery charging status. These commands with relevant access codes shall be displayed on the equipment in addition to being displayed at Control Desk in test room. 10.2.8.3 On failure of AC fuse, remote Card automatically sends fuse fail signal to Test Room Equipment along with its identity code. 10.2.8.4 Disabling and enabling of Command Codes through suitable authorization Code/Password or Key shall be desirable to prevent any unauthorized initiation. 10.3 EARTHING: Indian Railways Telecom Manual - 2021 Page 105 10.3.1. All non-current carrying metal parts of amplifier/equaliser equipment including armour and sheath of quad cable shall be bonded together and earthed. 10.4. MAINTENANCE SCHEDULE FOR REPEATER AND AMPLIFIER- EQUALISER SYSTEM EQUIPMENT ITEM TELECOM JUNIOR SR.SECTION TECHNICIAN ENGINEER ENGINEER Repeater/ Weekly Monthly Quarterly Amplifier- (Every (Every Equaliser installation) installation) Equipment i) Checking -do- -do- -do- Power Supply voltage at the input point. ii) Checking of -do- -do- -do- various cards in proper position. iii) Checking the -do- -do- -do- functioning of all the circuits. iv) Section wise ---- -do- -do- and end to end line up of all circuits. Batteries Weekly Monthly Quarterly (Every (Every installation - installation - checking checking only only to to ensure) ensure) i) Cleaning & -do- -do- ---- tightening of all connections ii) Measurement -do- -do- -do- of voltages and gravity Indian Railways Telecom Manual - 2021 Page 106 Earthing 3 Monthly 6 monthly Yearly (Every (Every (Every installation) installation) installation) i) Cleaning & -do- -do- ---- tightening of all connections ii) Measurement --- -do- -do- of earth resistance -x-x-x- Indian Railways Telecom Manual - 2021 Page 107