Track Circuits

 As per new SEM, Minimum length of Track Circuit is 26 m( Two rail length)

Glued joint Insulation  Resistance- Not more than 25M ohms in dry conditions and not less than 3 k ohms in wet conditions.

Stray Voltage- not more than 10 m Volt  track circuit upto 100m. 100mV for track circuit more than 100 metres.

Stray current- 

Not more than 10 mA for TC upto 100 Mts. 

Not more than 100mA for length of TC is equal or above 100 mts.

B type choke for 25 KV AC RE Area- 120 ohm impedence and 3 ohm Resistence.

QTA2 - pick up voltage 1.40 v ,  pick up current should be 140 mA.Minimum Excitation is not less than 125% of rated pick up voltage.Maximum  Excitation is not less than 300% of rated pick up voltage for plug in type Track Relay. Configuration 2F1B.AC immunity is 50V AC.

QBAT - pick up voltage 1.75V, max pick up current should be 175 mA.Minimum Excitation is not less than 122% of rated pick up voltage.Maximum  Excitation is not less than 235% of rated pick up voltage for plug in type Track Relay. Configuration 2F2B.AC immunity is 80 V AC.

All the track Relay are of 9 ohms.

Percentage of release of track Relay not less than 68%.

Track relay sensitivity depends upon percentage release.

Max Length of Track Circuit  - In Non RE, Max length of TC is 1000 mts in block section and 670 m in Yard for both type of Sleepers.Normally QT2 is used but QTA2 or QBAT can also be used in both cases.

In RE Area Stn yard,if  Sleepers are PSC, Max Lenth of TC is 350 metres for QTA2 track relay. Max length can be increased to 750 m by using QBAT track Relay.

 In RE Area Stn yard,if  Sleepers are Wooden,Max Length is 450 m.QTA2 relay used.

In RE Area Block Section  Max Length of TC is 450 metres for both types of sleepers.QTA2 any can be used.

Minimum Ballast Resistance - 

4 ohms/ km for Block Section  

2 ohms/km for Yard Section 

For RE , Non RE both, Any Sleeper

Maximum Rail Resistance- For RE and  Non RE both,

 TC length upto 700 m -1.5 Ohms/ km

TC length more than 700 m - 0.5 Ohms/ km

Dead Section- In big Yard there is portion where train can not be detected.Max length of dead Section is 1.8 m because motor trolley is the shortest train and its length is 1.8 m.

SRJ ( Stock Rail Joint) - Where stock rail of Point joints ( between first and second sleeper).This joint may be fish plated or welded. Distance of first Glued from SRJ is minimum 13 m but practically it can not be achieved at all places.However there is no issue of safety due to this.

Highest TSR - 0.5 ohms for DC track circuit and for AFTC outside their tuned length 

0.15 ohms for AFTC at the tuned portion.

Important Points -

1) QSPA1 is the first repeater of QTA2 or QBAT relay.

2) For replacement track of Starter Signal, Glued may be placed 0 to 3 m from Starter and HR of the Starter will be made slow to release so that CSR can be maximum.

3) For replacement track of Home  and Advanced Starter Signal, Glued may be placed at 13 m because there is no issue of CSR at these signals.

4) In case of berthing track having multiple track circuits sections,it is desirable to show individual Indications of each track circuit on panel.




Comments

Post a Comment

Popular posts from this blog

CRS , CST and PCE sanction

  Validity of CST sanction   is six months .Required when we are doing any changes in existing interlocking.e.g commissioning of BPAC Validity of CRS and PCE sanction are same (01 year). PCE sanction is required only for closing the LC gate.Earlier it was with CRS, now delegated to PCE. ESP,SIP,SWRD,PD and SWR required to be attached with PCE sanction.  CRS sanction is must when do any change in interlocking,e.g.any new line is opened. Validity of CRS sanction is 01 year. CRS permission is required in following cases. a) Additions/extensions or alterations to the existing block, Signalling and interlocking installations b) Change in Block, Signalling and Interlocking installations. c) New stations temporary or permanent. d) Interlocking of level crossings, catch siding and slip sidings etc. CST Sanction   CST Sanction required in following works 1) Provision of Telephone at already Manned level crossings. 2) Provision of electrical & mechanical lifting barrier including emergency
Read more

Catch Siding and Slip Siding

  Catch Siding is provided to protect the station section, if the gradient is steeper than 1 in 80 falling towards the station section. Slip Siding is provided to protect block section if the gradient is steeper than 1 in 100 towards Block Section. Normal permissible gradient for Block Section is 1:1200 and for Station Section is 1:400. Reception of Trains in Catch Siding Stations- (a) Either a minimum of two Stop Signals shall be provided in rear of the Catch Siding points or the First Stop Signal shall be at an adequate distance equal to Block overlap from the catch siding points. (b) A train shall first be brought to a stop at the First Stop Signal, before the Catch Siding points are set for the main line and the reception signals shall not be taken 'OFF' unless the following conditions are satisfied. (1) The line on which the train is to be received is clear and the train is to be received on the main line.  (ii) The points leading to the Catch Siding as well as all the Poi
Read more

Railway Establishment and Stores

  Max LAP approved one time - 180 days .( if available in his account). Max LHAP approved one time - 24 months ( if available in his account). Leave not due - Max 360 days in service. Can be sanctioned on medical grounds  Compensatory casual leave granted to Group C &D employees other than supervisory staff for attending on Sundays and holidays. Special casual leave    It is sanctioned for participation in sporting events/events of national importance,for scouting duties and family welfare. Special casual leave can be granted in following cases. Administration of operative society members. Participation in scouts . Participation in sports activities  Participation in railway union activities etc In bandh,curfew and national calamity. A railway Servant,who has taken CL for half a day on the afternoon of a working day due to unexpected sickness or compelling grounds and he has no CL at his credit, may as an exception to general rule,be permitted to combine half a day’s CL with regu
Read more