CH 17 Section 6-8 Axle Counters PDF

Section 6: Axle Counters - General 17.6.1 Axle Counter consists of track device (axle detector) mounted on the rails, track side electronic equipment provided near the track and connected with track device & evaluator. Evaluator monitors the counts of track device(s) to give cle...

Section 6: Axle Counters - General 17.6.1 Axle Counter consists of track device (axle detector) mounted on the rails, track side electronic equipment provided near the track and connected with track device & evaluator. Evaluator monitors the counts of track device(s) to give clear/occupied indication. Evaluator/track side electronic equipment may be kept in relay room or site. (a) Digital Axle Counters of approved type may be used in lieu of track circuits to prove the clearance of a portion of track. (b) Axle Counters may also be provided in lieu of conventional track circuits for block working, viz. Intermediate Block Signalling, Automatic Signalling, Block Working controlled by track circuits, etc. (c) Digital Axle Counter (DAC) may be preferred on girder bridges in lieu of DC track circuits. 17.6.2 Typical usage of Axle Counters is for following applications: (a) Intermediate Block Stop Signalling. (b) Automatic block signaling. (c) Station Section having poor drainage, flood prone sections. (d) Block Section Proving of Clearance (BPAC). (e) Tracks having problem of rust. (f) Tunnels and bridges as per site requirement. 17.6.3 Trolley Suppression Axle counter shall not count standard 4 spoke wheels of push trolleys. Note: In those sections where certain models of Motor/Light motor/Moped/Scooter trolley in use which may not get detected shall be taken care of, by suitable provisions in Station Working Rules, working Time tables and subsidiary Rules. Such Trolleys shall be run as per GR 15.25 for working of Motor trolleys. Section 7: Installation of Axle Counters 17.7.1 The installation of Axle Counters shall be done as per prescribed installation guidelines of OEM and approved pre-commissioning checklist. Chapter 17: Train Detection Track Circuits & Axle Counters Page 348 of 530 17.7.2 The important features of the installation procedure are: (a) Trolley Suppression: On sections where trolleys are in operation and existing axle counters do not have inbuilt trolley suppression arrangement, the arrangement shall be provided to prevent the operation of system by insulated trolleys. Trolley suppression arrangement shall be closed track circuit and track devices shall be fixed on rails within the boundaries of track circuit. It is possible to dispense with the provision of trolley suppression arrangement for track devices provided on point zone portion by using approved circuits for this purpose. On sections where non-metallic wheels are used, trolley suppression arrangement can be dispensed with. Note: In future, digital axle counters having inbuilt provision of trolley suppression shall only be provided. (b) The distance between the two adjacent axle detectors of different axle counters shall be at least 2 meters or as specified in OEM manuals, so as to minimise mutual interference. (c) To protect axle detectors against damage (from hanging parts of moving trains), deflectors shall be provided, on both sides of the axle detectors on single line and one side on double line. (d) The track side electronic equipment shall be housed at a location close to the axle detectors so that the length of cable between the track side electronic and the axle detectors is minimum and does not exceed the limit recommended by the manufacturer. The equipment shall be placed at a level well above the flooding level of the area. (e) The incoming cables from axle detectors and evaluator may first be terminated on a cable distribution board to provide facility for testing. (f) Wherever applicable, the transmitter and receiver coil cables between axle detector and associated track side electronics shall be laid in different pipes as prescribed by OEM. (g) Ensure minimum of 400 mm Sleeper spacing & packing of sleepers in between track device (sensor) are fitted & fitting do not vibrate under train movement & packing of the same shall be done, if required (h) Track side electronic equipment shall be operated from Central power supply like DC–DC converter of approved type preferably used for feeding evaluator with adequate battery backup. At remote locations track side electronic equipment may be provided with separate power supply. The input power supply shall have a maximum ripple of 50 mV peak to peak/10 mV rms. (i) The evaluator shall be installed preferably in a relay room or at a location which is not accessible to unauthorised persons. Equipment shall be installed at a high level, well above the flooding level of the area and protected from rain water. It shall be fixed on a separate shelf away from signalling relays. As far as possible, it shall be located away from any source of heavy electromagnetic interference like industrial machinery, motor/generator or welding plants, etc. Chapter 17: Train Detection Track Circuits & Axle Counters Page 349 of 530  (j) The power to evaluator is fed from a power supply like DC-DC converter of approved type with adequate battery backup. Each evaluator shall be provided with a separate DC-DC converter for better availability. The input power supply shall have a maximum ripple of 50 mV peak to peak/10 mV rms. (k) All lead connections to and from battery and DC-DC converter shall have adequate current capacity to ensure that the voltage drop does not exceed 0.2 V. These connections at terminals shall be secured properly and should preferably be made through lugs to give firm contact. (l) Connections between battery, battery charger and DC-DC converter shall not be bunched with any other wires. These wires shall preferably be laid at least 150 mm from any other bunch of wires. Positive and negative wires shall be twin twisted to avoid interference pick up especially when the lead wires are long. (m) Where ever Integrated power supplies are provided, power for axle counter shall be taken from nominated DC-DC module. (n) Redundancy in train detection devices may be provided for all train detection device in Block section and at vulnerable Track sections within station section. Redundant system shall be independently powered through independent power source and separate cable. 17.7.3 Communication Media (a) The quad cable or PIJF Telecom Cable used with axle counters shall be of approved type. The Transmission loss, cross talk measurements shall be within limits specified for the axle counter to be installed. Optical Fibre Cable (OFC) may also be used for communication with suitable interfaces. (b) All precautions prescribed for laying and installation of communication cables shall be strictly followed. 17.7.4 Axle Counter Resetting - Block Section/Intermediate Block Signalling/ Automatic Signalling: (a) Preparatory reset arrangement shall be provided, so that whenever the axle counter shows fault condition; the same can be reset by the on duty Assistant Station Master/Station Master, after ensuring that the monitored portion is clear of vehicles. The following precautions shall be followed for resetting. (i) Once the Axle Counter has failed and the concerned signal cannot be taken off, the on duty Station Master (ASM) of Train dispatching station shall positively verify the clearance of the block section with the on duty Assistant Station Master (ASM) of Train receiving station by exchange of private numbers and record the same in Train Signal Register (TSR) by both the stations. After ensuring that the block section is clear of vehicles, Axle Counter`s reset operation shall be initiated by cooperative effort between the ASM`s of the dispatching and the receiving stations. (ii) The circuitry shall be such as to obviate the possibility of the resetting by the dispatching/receiving station independently. Chapter 17: Train Detection Track Circuits & Axle Counters Page 350 of 530  (b) The reset box shall be operated by a key which shall be kept locked in a separate box kept in the SM’s office. Each and every operation of the reset button shall be counted on a non-resettable type counter and shall be recorded in the Train Signal Register by both the SMs, indicating the movement before and after the operation of the reset button. During inspection of the stations the Signal and Traffic Inspecting officials shall specifically checkup and ensure that the system of exchange of private number is being followed meticulously. (c) The procedure of resetting, verification of clearance of concerned axle counter section from any obstruction/vehicles before resetting is initiated and piloting of the first train shall be clearly laid down in the Station Working Rules. 17.7.5 Axle Counter Resetting - Station Section: Where Axle Counter is provided in station section, the following procedure shall be followed for resetting: (a) Cooperative Type for Point Zones/loop lines/siding: Once the Axle Counter has failed and is showing fault condition, the on duty ASM/ Station Master (SM) shall first arrange to verify that line on which train is to be received is physically clear of any obstruction. Such physical verification of failed Track section shall be done through Line verification box (LV box) which shall be installed close to the line to be verified. The resetting shall be cooperative and done jointly by the on duty ASM along with another Operating Staff, who shall verify physical clearance of Line and operate the line verification box for the failed Track section of axle counter. (b) Main lines/Run through lines: Preparatory reset arrangement shall be provided. (c) The reset box shall be operated by a key which shall be kept locked in a separate box secured in the SMs office. Each and every operation of the reset button shall be recorded in the Train Signal Register by the ASM and during inspection of the station; the Signal and Traffic inspecting officials shall specifically check up the procedures being followed in respect of the above resetting device and ensure that laid down procedure for resetting is being followed. (d) This procedure of ensuring that the monitored portion is free of any vehicle before resetting is done, shall be clearly laid down in the Station Working Rules. (e) The first train after the reset operation may be either received on calling-on signal or piloted as per the extant rules after verification of the clearance of the reception line. Chapter 17: Train Detection Track Circuits & Axle Counters Page 351 of 530  Explanatory Note: An overview of Axle Counter resetting is shown in Table-below. S. Line/Section Type of Reset To be applied by Axle Counter status No. (1) (2) (3) (4) 1 Block Section/ Preparatory On duty ASMs at After operation in Column (3) Auto/IB section Reset both ends of and will show ‘clear’ only Block Section after matching ‘count in’ with ‘count out’ 2 Main line/ Run Preparatory On duty ASM -do- through line Reset 3 Point zone/loop Conditional On duty ASM Will show ‘clear’ after line/Siding Reset and another operation in Column (3) operating staff 17.7.6 If Axle Counter cannot be reset, due to any reason or it fails again after resetting, it should be treated as failed and the Signalling maintenance staff should be advised immediately for rectification. Section 8: Maintenance of Axle Counters 17.8.1 Maintenance of axle counters shall be done as per RDSO's guidelines and maintenance recommendations of equipment manufacturers. (a) In case of double rail mounted track devices there shall be no differential creep between the two rails of the track to the extent as to alter their inter distance beyond the permissible tolerance, it is, therefore, necessary that 4 rail lengths on either side shall be well anchored. (b) Anchoring of track on either side of the rails where track devices of axle counters are fixed, shall be closely watched by the Permanent Way staff to ensure that there is no differential creep. (c) Tie Tamper shall not be used for 4 sleepers on either side of the track devices. Incidentally they should be manually maintained. (d) Replacement of components of Axle Counters shall be done with utmost care and as per technical manuals of OEMs. As a general rule, any maintenance activities in track device area, like, ballast packing & rail changing etc. that require disconnection of track devices and adjustments of axle counter parameters shall not be done in working system. Where required, maintenance staff shall take proper disconnection, duly de-energizing the related sections of Axle Counters from CT rack/disconnection terminals before starting indoor/outdoor maintenance activities. Once work is completed the section should be connected/energised following all precautions related to resetting, checking of parameters as stipulated and physical clearance of track section before reconnection. Activities like measurement of parameters, cleaning etc. which does not interfere with working of system, may be carried without disconnection. Chapter 17: Train Detection Track Circuits & Axle Counters Page 352 of 530