A seminar on

distribution of traction return current in AT

presented by

Manjeet Malav

EE final year

09EEJEE026

contents• Introduction

• Track circuit

• Description of track circuit

• Longitudinal section of railway system

• System analysis

• conclusion

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.

Track circuit

Double rail with insulating joints and impedance bondsTx = transmitterRx = receiver

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.

Longitudinal section of railway system

Modeled electrical parameters values

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

Fig. Rail current track 1

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.

Thank you All