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1. A
seminar on
distribution of traction
return current in AT
presented by
Manjeet Malav
EE final year
09EEJEE026

2. contents
• Introduction
• Track circuit
• Description of track circuit
• Longitudinal section of railway system
• System analysis
• conclusion

3. introduction
• Complexity of railway system increasing day by day
which requires simulation based technique to
ensure electrical compatibility of the whole
electrical system .
• New and old locomotives are in operation on the
same line.
• The path of traction return current flowing from
rolling stock axels back to the supply is composed
of traction rails.

4. Track circuit
Double rail with insulating joints and impedance bonds
Tx = transmitter
Rx = receiver

5. Description of track
circuit
• Transmitter –
It applies a differential voltage to the rails.
• Receiver –
picks up the voltage across the rails at the other
end of the loop.
• Double rail track circuits with impedance bonds
use IRJs on both rails and the return current flows
back through the impedance bonds.

6. Longitudinal section of
railway system

8. Modeled electrical
parameters values

9. System analysis
• Variables which are computed
V1rr , V2rr = voltage b/w rails
Ier , Iir = current in the rails
Iro , Irg = current in return conductors
IE = stray current

10. Fig. Rail current track 1

11. conclusion
• Only a small portion of the return current flows
through the rails.
• System resonance may occur inside the frequency
band.
• The amount of current leaving the system is
proportional to the conductance to earth.
• The earth resistivity does not influence the
distribution of the return current.

12. Thank you
All