The Z of the prospective short circuit current,is it mostly resistive or reactive ?

[tonikh]

Hello,

I want to calculate the prospective short circuit current at a remote distribution board & this is my dilemma.
I have from the supply a prospective short circuit current of 20 KA and supply voltage of 400/230V.

So if I do the following Zin = 230 /20,000 I get Zin = 0.0115 ohm

Now here is the problem,I want to add the resistive & reactive part of the phase conductor to the impedance that i just got, but Zin is a complex number & i dunno if it is mostly resistive or reactive,but I am pretty sure both are present in it

So to add the impedance of the conductor with Zin,shall I consider Zin mostly reactive and add it with the reactive part of the conductor, or shall i consider it resistive and add it with the resistive part of the conductor, or shall i simply add the two complex impedances.

Thank you,
Really Appreciated

 

[mechelec]

Re: The Z of the prospective short circuit current,is it mostly resistive or reactive

to find out you will need an occiloscope and check the voltage and current phase relationship but beware this will change depending on the day you measure as other customers may be introducing inductive or capacitive loads and more or fewer harmonics onto the system.
That said i would treat it as resistive and add your impedence complex or not to it