D.C. TRACK CIRCUIT - Indian Railways

1 CAMTECH/S/2004/ TRACK CIRCUIT Ver TRACK CIRCUIT1. Introduction TRACK CIRCUIT is a low powered electrical circuitin which running rails are used as a part. Withthe help of TRACK CIRCUIT , one can easily identifywhether the particular section is clear oroccupied by a train/vehicles or TRACK CIRCUIT isin failed advantages of DC TRACK CIRCUIT are : It is very simple to maintain. It is highly reliable for effective and saferunning of DC TRACK CIRCUIT has mainly two ends feedend and relay end as shown in fig.

2 No. TRACK CIRCUIT gives two indications. Yellow/White/No light indication -When TRACK CIRCUIT portion is clear line is unoccupied. Red indication - When TRACK circuitportion is occupied by a vehicle or trackcircuit is in fail TRACK CIRCUIT Ver 20042. Requirements Permanent Way Requirements Glued joints or insulation joints of approvedtype are to be provided for definingboundary of TRACK CIRCUIT . In all future worksof TRACK circuiting, glued insulated joints isto be preferably been provided.

3 insulated joints wherever provided is to bemaintained as square joints. Wherestaggering can not be avoided the distancebetween staggered joints shall not exceed theminimum wheel based of the vehicles. Rail ends of insulated joints shall be squareand true. All rough edges and burrs shall beremoved from bolts holes. Battered endsshall be put right and the gap between therails is to be equal to the thickness of the endpost. Fish bolts at the joints must be kept tight andthe sleepers well packed in the vicinity ofthe joints.

4 Proper drainage should be ensured so as toavoid flooding of tracks during rains,particularly in the yards where watering ofcoaches is done and in the water columnsand ash pits. It would be desirable to providewashable concrete aprons on platform linesat originating stations, in TRACK TRACK CIRCUIT Ver 2004 Ballast shall be kept clean throughout thetrack circuited section should be taken dosee that the ballast is kept clear off the railsand rail fastenings.

5 The clearance from thefoot of the rail should not less than 50 screened ballast right up to theformation level shall be provided. Rail ends shall be kept free from brake-dust,sand, rust, other foreign materials etc. allrough edges and burrs at rail ends must beremoved. To avoid crushing of end posts of insulatedrail joints due to creep at least one rail lengthin either side of insulated joint should beprovided with anti creep devices. Rail screws should preferably be used inplace of dog spikes at insulated joints.

6 Wooden sleepers concrete sleepers or anyother approved type insulated sleepers shallbe provided for TRACK circuiting. Concretesleepers where used shall have a minimumresistance of 500 ohms between insert-to-insert. Where short welded rail panels are used,SWR shall not but against insulated rails lengths of 13 meters/12 metersshall be interposed to isolate short weldedrail from insulated joint. This standardlength of rails shall be anchored effectivelyto arrest movement in either direction.

7 In case of turnouts and crossings, insulatedstretchers, insulated gauge ties plates andCAMTECH/S/2004/ TRACK CIRCUIT Ver 2004insulated crossings plates shall be providedas per approved drawings. GEN liners shall be provided in the TRACK -circuited area using concrete Types of TRACK circuits A closed type TRACK CIRCUIT shall be provided toprove the clearance of rail TRACK . Double rail TRACK CIRCUIT Double rail TRACK CIRCUIT is to be provided onnon RE areas, as for as practicable.

8 In double rail TRACK CIRCUIT both the runningrails are insulated from adjoining sections byinsertion of block + -InsulationjointsDouble Rail TRACK CIRCUIT (Figure 1)CAMTECH/S/2004/ TRACK CIRCUIT Ver 2004 Single rail TRACK CIRCUIT In RE area, generally single rail trackcircuit is used where one of the rails isreserved for the traction return rail is referred to as the un-insulatedrails. Any connection from the OHE mast orother structure shall be made only to theun- insulated rails.

9 Similarly, connections for the returncurrent at feeding points as well as frombooster transformers and returnconductors shall be made only to the un- insulated rail. Other rail carries positive polarity of DCrack CIRCUIT . This positive polarity rail isinsulated from either TRACK CIRCUIT Ver 2004 TRInsulationJoint6 Amp Fuse Choke + -Single Rail TRACK CIRCUIT (Figure 2) As far as practicable, the rail adjacent tothe mast shall be utilised as theinsulated rail.

10 However, this may notalways be possible, particularly in yardswhere there are a large number of pointsand crossings or where the mastsCAMTECH/S/2004/ TRACK CIRCUIT Ver 2004are not always on the same side or wheretrack circuits are staggered. In single rail TRACK circuits, in the eventof a break in the un- insulated rails, veryheavy current will flow through thetrack relay as well as the equipment atthe feed point. To avoid this the un- insulated rails of the adjacent tracks shallbe cross-bonded at intervals of not morethen 100 mts.