BONDING

Railway Train detection

Indian Railway Signalling Network Rail

Railway Train detection,SYSTEM SAFETY,PERFORMACE REQUIREMENTS,OCCUPATIONAL SAFETY,MAINTAINABILITY,RELIABILITY,OCCUPATIONAL SAFETY,ENVIRONMENT,DISCRETE SYSTEM,CONTINUOUS SYSTEM,MOVING BLOCK SYSTEM,Block Systems,Level Crossing,BONDING

Railway Train detection

PERFORMACE REQUIREMENTS

  • SYSTEM SAFETY
  • OCCUPATIONAL SAFETY
  • RELIABILITY
  • MAINTAINABILITY
  • ENVIRONMENT

SYSTEM SAFETY -GENERAL

SYSTEM SAFETY

 

SYSTEM SAFETY

  • SAFETY INTEGRITY LEVEL
  • SAFETY PERFORMANCE BENCH MARK
  • SERIES TRACK CIRCUIT BONDING
  • OVERCURRENT PROTECTION
  • INSULATION AND ISOLATION
  • SURGE ARRESTERS
  • POSITION OF TRAIN DETECTION EQUIPMENT

OCCUPATIONAL SAFETY

  • HIGH VOLTAGE
  • TRACK CIRCUIT FUSING
  • INSULATION OF TERMINALS
  • SAFETY LABELLING
  • SAFETY EARTHING
  • CONDUCTOR RAIL PROTECTION BOARDING
  • NEWLY SPECIFIED SYSTEMS

 

RELIABILITY

  • DUPLICATE TRACK CIRCUIT RAIL CONNECTIONS
  • PARALLEL(YELLOW) BONDING

MAINTAINABILITY

  • COMMUNICATIONS
  • CUT SECTION MONITORING
  • PROVISION OF DISCONNECTION BOXES
  • PROVISION OF CONDITION MONITORING

ENVIRONMENT

  • TRACK CIRCUIT SYSTEM
  • AC ELECTRIFIED
  • DC ELECTRIFIED
  • DUAL ELECTRIFIED
  • NON ELECRIFIED

 

CONTINUOUS SYSTEM

To detect presence or absence of vehicles with in the limit of track section E.g.Track circuits, Axle counter

DISCRETE SYSTEM

 To detect that a train has reached ,is passing or passed a specific position . Discrete systems are generally provided in addition to continuous system E.g.. Treadles

 

MOVING BLOCK SYSTEM

To detect absence of vehicles with in an envelope ahead of a train that progress with the passage of the train.

BALLAST RESISTANCE AND TRACK CIRCUIT LENGTH

  • BALLAST RESISTANCE TYPICAL VALUES 2 TO 10
  • RAIL RESISTANCE 0.25 OHM/KM AND RAIL IMPEDENCE DEPENDS ON FREQUENCY

   50 HZ  –  0.3 OHM/KM

   400 HZ – 2.5 OHM/KM

   2000HZ – 10 OHM/KM

THESE IMPEDENCE VALUES MAY BE INCREASED FURTHER BY LARGE TRACTION CURRENT ,DUE TO RAIL BEING DRIVEN TOWARD SATURATION.

Train Detection Overview

Block Systems

  • Block Systems require the absence of a train to be proved either by
  • Continuous train detection or
  • Entry and/or exit train detection by discrete track circuit or other devices.

Level Crossing

  • For automatic level crossing operation required to prove :
  • The absence of an approaching train to allow the crossing to be opened to road traffic, and
  • The presence of the train on the exit side before the crossing can be normalised after operation.

Other Functions

  • Indicating on the signaller’s display system
  • Approach releasing a signal
  • Allowing a permissive route to be set
  • Allowing a ground frame to be released
  • Train approaching indication / warning
  • Train detection device may also be used to calculate the speed or acceleration of a train
  • The length of a train may need to be measured.

Different types of train detection systems

  • Track circuits
  • Axle counters
  • Other type of wheel detector, e.g, treadle, electromagnetic proximity device(used for HABD)
  • Supplementary systems, e.g, track circuit assistor interference detector(TCAID), track circuit interrupter.

TCAID is a train detection equipment mounted on the track which detect the presence of a working of TCA. TCA is a another train mounted device which provide to improve the operation of track circuit.

Key attributes and limitation of each type of track circuit

Type Suitable for Lightly Used Lines IRJs Required Immunity From

50Hz a.c.          d.c.

Suitable for S&C
DC medium voltage (AC immune) #1 Yes Yes Yes No Yes
DC Diode #1 Yes Yes No No No
T1.21 #1 No No Yes #4 Yes No
HVI #1 Yes Yes Yes Yes Yes
DC Low voltage plain No Yes No No Yes
DC Low voltage(AC immune) No Yes Yes No Yes
DC medium volt plain Yes Yes No No Yes
DC medium voltage AC immune/DC tolerant Yes Yes Yes Yes #2 Yes
AC 831/3 Hz Vane No Yes Yes Yes Yes #3

Key attributes and limitation

 

BONDING

  • SERIES AND PARELLEL BONDING
  • DETECTION OF RAIL BREAKS
  • BONDING TYPES

BONDING

BONDING

BONDING

YELLOW BONDING

YELLOW BONDING

PERMISSIBLE SPURS AND SPUR BONDING

PERMISSIBLE SPURS AND SPUR BONDING

 

CLEARANCES AND PHYSICAL STAGGERING

CLEARANCES AND PHYSICAL STAGGERING

 

 

 

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