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DanDel, Yes, you are correct that I did post this question recently but for some reason it was removed. You are also spot on that I'm working on the fault currents for a railway line. As you have suggested, I think I can assume all sources peak at the same time as the R-T units all have the...

Sorry, I should have made this clear. This is actually for a DC distribution system. I suppose paralleling these impedances should lower the overall inductances. Would the below formula be correct to use? Leq = (Rp/R1)^2 * L1 + (Rp/R2)^2 * L2 + (Rp/R3)^2 * L3 where Rp = 1/(1/R1 + 1/R2 + 1/R3)

When considering DC short circuit faults of an overhead line system occuring immediately outside one of the substations, contributions from the adjacent substations should be taken into account. If I take these as three RL circuits, i.e the local, and the two adjacent circuits with 1. R1 & L1...

hvcad, Thank you, I found your explainations very useful. rail1996

Hi All, Still doing my system fault level calculations. I am stuck in trying to work out the equivalent inductances of two RL circuits. One circuit has Req & Leq and the other has Rsb & Lsb. From previous work, I have the formula for the equivalent inductance Lp = (Rp/Req)^2 * Leq +...

We often see the term commutating reactance associating with rectifier transformers. Can someone please tell me if that is just simply the transformer impedance? If not, can we derive the Tx impedance from the commutating reactance? Thanks in advance!

I have used Philip's 'calculux' software package previously and found it is quite a user friendly program to use. http://www.eur.lighting.philips.com/int_en/prof/about/d...

Is it possible to calculate the zero sequence X, positive sequence R & X if I was just given the Z% of the transformer, say 11%? Thanks in advance.

Please can somebody tell me if there are usually any differences between the positive/negative and zero sequence impendances for HV power cables? I need to carry out a short circuit analysis for a HV network and the cable data I am provided with are the 'Maximum a.c resistance of conductor...

I have used Philip's 'calculux' software package previously and found it is quite a user friendly program to use. http://www.eur.lighting.philips.com/int_en/prof/about/downloads/index.html

I have been asked to calculate the fault current that flows through the armour of a power cable. Can someone please tell me how this is differ from the traditional line-earth fault calculations?

Jghrist - Yes, I wish to calculate the asymmetrical fault level for OHL-rails faults and the loop inductance is required. RAMConsult - Thank you for your suggestion. I've serached through this but with on luck.

Does anyone know how to calculate the loop inductances of some DC overhead line railway system. i.e +ve supplied by overhead wires and -ve return via the rails.

Please tell me what the 'n' stands for on a Dyn11 vector group transformer.