Short circuit analysis of DC Traction Power System - Running rails and Conductor/3rd Rail impedances

[Oblsss]

Dear Sirs,

I am trying to build a model of a DC Traction Power System, composed of 10 Traction Substations (TSS) feeding a third rail, also known as conductor rail, system (750 V DC).
The main objective is to build a representative model that will confirm the points where the max/min di/dt gradients appear for the DC Breakers protection settings.
A more detailed model will be developed at a later stage.

My main problem is finding tabulated values or a relatively simple way of calculating the impedances of the conductor rail and the running rails (which form part of the return circuit).
Could you please direct me through some relevant sources as what I have found so far is quite complex for the application needed at the moment (needs time to implement).

Third/Conductor Rail System

Thank you in advance!

George P.

 

[cranky108]

There is a rail system testing center in Pueblo Colorado that does testing on cannery systems. I don't know the official name, but they can help.
If I recall from some what I was told, that 30% or less of the current travels through the steel of the rails, while the rest travels through the earth, or copper neutral. Don't quote me on that, as it has been years since I heard that.

Might also reach out to the light rail engineers in either Denver, or Sacramento. Also there are several other around the US.

 

[Oblsss]

cranky 108 thank you for your answer!

Unfortunately it is not easy for me to communicate with your above references as I live and work in Europe!
The system I am talking about does not have a catenary feeding line nor a copper neutral (you can click on the link to see a layout of the system) but any info/reference on the calculation of DC Traction system impedances is welcomed!!

 

[cranky108]

Sorry, I am a utility engineer. My involvement with rail power is from a utility perspective.
I do know that there is generally a copper runner that attaches to the rail from time to time.
That said, I am in the USA, so things maybe different here.
Maybe not so different though, as many DC tractions systems here operate at 600V DC, but I do know that Denver light rail operates at 800V DC (an article that was posted on the SELINC web site had a paper on the signaling).

 

[FacEngrPE]

Almost everything on this subject is behind a paywall.

There are some recent papers published on this subject at IEEE.

https://ieeexplore.ieee.org/document/338437

and on some research publication sites

https://www.researchgate.net/publication/288773712_AC_DC_Railway_Electrification_and_Protection

https://www.semanticscholar.org/pap...nter/4977d796b2eca39d89b9d3a52681f297bd427951

https://www.semanticscholar.org/pap...Hill/ada8b30e19d3cbf04793a6fdf9a107a492149f05

https://www.researchgate.net/public...of_Traction_Rails_at_Power_Frequency_A_Survey

This looks like a rather specialized field.
The attachment is interesting as it provides a method for doing what you are looking for.
Your mileage may vary.