CH 17 Section 3 PDF - Train Detection Track Circuits

Min. Max. Section Ballast TSR Length of Sl. RE/ Type of Track Relay to Sleeper (Yard/ Resistance in Track No. Non-RE...

Min. Max. Section Ballast TSR Length of Sl. RE/ Type of Track Relay to Sleeper (Yard/ Resistance in Track No. Non-RE be used Block) in Ohm per Ohms Circuit in Km meters 1 Non-RE *Wooden/PSC Block 4 0.5 1000 QT type 9 ohm 2 Non-RE *Wooden/PSC Yard 2 0.5 670 -do- 3 RE *Wooden Block 4 0.5 450 QT 9 ohms AC immune 4 RE *Wooden Yard 2 0.5 450 -do- 5 RE PSC Block 4 0.5 450 -do- 6 RE PSC Yard 2 0.5 350 -do- 7 RE PSC Yard 2 0.5 750 QBAT in conjunction with QSPA1 with B type choke at relay end (* where existing) 17.2.10 Track Feed (a) Approved type of secondary cells shall be used for feeding track circuits. (b) Secondary cell(s) shall be used along with battery charger/solar panel of adequate capacity. (c) Separate feed shall be provided for each track circuit. Section 3: Maintenance of DC Track Circuits 17.3.1 General: Track circuits shall be so maintained that: (a) There is always a good connection between power feed and track, Relay and track and also between adjoining rails, through jumpers and rail bonds. (b) The ballast resistance always remains high and does not fall below prescribed minimum values. (c) The limiting resistance shall be as high as possible. (d) The insulating joints are of high resistance. (e) The surface of rail is clean and is free of dust, sand and foreign materials. (f) The circuit is properly energised during wet weather on minimum ballast resistance conditions and during dry weather on maximum ballast resistance conditions. The track circuit shall not be over-energised to such an extent that the shunting value drops below 0.5 ohms for all types of track circuits. These values shall be obtained irrespective of whether the track is provided with concrete sleepers or wooden sleepers. (g) The connection of DC track relay shall be quarterly interchanged to prevent permanent magnetisation. Chapter 17: Train Detection Track Circuits & Axle Counters Page 336 of 530 17.3.2 DC Track Relays (a) Pick up and drop away values shall be maintained within the limits specified by the manufacturer. (b) Track relays shall be inspected visually every quarterly by the JE/SSE and the following visual checks conducted: (i) Movement of armature and contact carriage (ii) Wiping of contacts (iii) Arcing of contacts, if any (iv) Pitting or charring of contacts (v) Dust on contacts (vi) Electroplating (vii) Corrosion, rusting of components (viii) Cracks or breakage in components (ix) Presence of fungus, if any (x) Charring of cover near contacts (for plug-in relays) (xi) Correctness of label (xii) Presence of seal (c) The defective track relay should be immediately replaced and a brief report stating the nature of the defects shall be submitted to ASTE/DSTE/ Sr.DSTE. On no account should any attempt be made by the field staff to rectify the relay. (d) Plug in type track relays have to be replaced on completion of 12 years or earlier if warranted by the actual condition of the relay and/or its usage. 17.3.3 Insulated Rail Joints (IRJ): Insulated Rail Joints shall be maintained in accordance with the instructions given in Booklet No. STS/E/IRJ/IMI "Installation and Maintenance Instructions for Nylon Insulated Rail Joint" issued by the RDSO/Lucknow, with particular attention being paid to the following: (a) Before opening an insulated rail joint, the components required for replacement, conforming to the rail section, shall be kept ready by the side of the track. (b) For replacement of an end-post when there is no gap at the Insulated Rail Joint, loosen the rail fastening and pull back the rail and insert end-post between the rail ends. (c) It is imperative that when an insulated rail joint is provided at least three sleepers on either side of the insulated rail joint shall be packed properly. Chapter 17: Train Detection Track Circuits & Axle Counters Page 337 of 530  (d) Fish bolts shall be kept tight. Nuts shall be tightened several times during the first two weeks after installation/replacement, until all components of an insulated rail joint are firmly set. (e) A metal flow is seen often at the rail-table at the joints. Such metal flow of metal forms a lip and creates sharp burrs at the rail ends. Projections formed at the rail ends shall be chiseled without damaging the end post so that these do not bridge the rail expansion gap and cause a short circuit. (f) Brake block dust, which may accumulate on the head and sides of the end post and top surfaces of the fish-plates, shall be brushed off frequently so that the possibility of electrical conductivity being established between the rail ends is eliminated. (g) Opening & fixing of fish plates of Nylon insulation joint for installation/ replacement of joint shall not be done by S&T staff (as it is the responsibility of Engineering Department). (h) Special type pandrol clips ('J' type) shall be provided at Nylon insulation joints/glued joint to avoid touching of pandrol clip with the fish plate. (i) Periodic coating by insulating varnish/epoxy over the nylon-insulated joint/glued joint to avoid shorting due to brake dust shall be done. A faulty insulated joint may be detected by taking the voltage readings across the track relay terminals and noting if this reading changes when the adjacent track circuit feed is shunted or disconnected. Any change in the voltage reading will indicate a faulty insulated joint. 17.3.4 Stretcher Bars and Point Rodding Connections Insulation for stretcher bars and point rodding shall be periodically checked to see that they are in sound condition. All defective insulation shall be changed. 17.3.5 Bond Wires/Rope Wires (a) Bonds shall be inspected frequently and maintained in good condition. (b) Bonds shall be painted with aluminum paint, where bond corrosions are excessive. (c) Voltage reading may be taken at every 15 rail lengths or less as required by special track circuits, to determine if the variation in voltage is gradual throughout the track circuit. If any unusual variations are found between any two readings, defective bonding may be detected by taking readings every rail length in that section or by inspection of each bond. 17.3.6 Jumper Connections: Jumper connections shall be inspected frequently and maintained in good condition. Long jumper connections shall be properly secured. Chapter 17: Train Detection Track Circuits & Axle Counters Page 338 of 530 17.3.7 Ballast: Minimum ballast resistance of track should not be less than 2 ohms per km in station yard and 4 ohms per km in the block section. Note: Wherever PSC Sleepers are used, availability of insulated liners upto a minimum level of 97% shall be ensured. 17.3.8 Drainage (a) Special attention shall be paid during the rains to track drainage. Defects, if any, shall be reported to the SSE/JE(P-Way). (b) All cases of defective valves of overhead water pipes in track circuited area shall be reported to the Inspector of works SSE/JE(Works). 17.3.9 Joint Inspection of Track by S&T and Permanent Way Inspector (a) The track circuited portion of the track shall be jointly inspected by SSE (Signal)/incharge and SSE(P-way)/incharge and jointly by Sectional SSE/JE (Signal) & SSE/JE (P-way) at least once in six months. (b) This is in addition to routine inspections to be carried out by each Branch. The condition of rail and insulation at the rail joints, ballast and sleepers, abnormal collection of brake dust, rusting of the rail and drainage system of the yard shall be particularly noted, it shall be ensured that percentage of missing liners for track circuit length not to exceed 3%. Maintenance work found necessary on insulation joints after such inspection should be carried out jointly. 17.3.10 Train Shunt (a) A Train shunt test shall be taken every quarter and every time the track circuit is adjusted or any alteration is made. (b) Shunt test shall be taken not only at relay end but also at other parallel portions of the track, such as, turnouts and crossovers. 17.3.11 Track Circuit Test Record Card (a) Track circuit test record Card No.S&T/TC-1, Annexure: 17-MS1 for DC track circuits, shall be maintained for each track circuit. For other types of track circuits, suitable record card may be framed by the Principal Chief Signal and Telecommunication Engineer. Readings shall be recorded every six months. Suitable remedial action shall be taken when abnormal readings are noticed at any time. (b) Test cards shall be easily accessible for inspection by officials. (c) The test card shall be kept up-to-date in accordance with the instructions given on the cards. 17.3.12 Track Batteries/Track Feed Apparatus: Track batteries or the track feed apparatus, where provided, shall be so arranged that the track relay will operate under the most adverse conditions. Batteries shall be kept in good fettle and special care shall be taken in maintenance of the cells. Chapter 17: Train Detection Track Circuits & Axle Counters Page 339 of 530