generator - thevenin impedance
generator - thevenin impedance
(OP)
I'm using some software to perform a fault study on a distribution system. When I input a substation (ie. generator) I have to specify the 3 phase fault current and and the short circuit ratio (X/R). From this, the program determines the positive and negative thevenin impedances....the zero sequence is left blank.
My question is how do I determine the correct zero sequence impedance ? If the configuratin is "star" is the zero component 0+jX (where jX is the same as the positive and negative sequence components)? When I do this, my calculated values and the ones the computer spits out are quite different.
Any help would be much appreciated
Thanks
My question is how do I determine the correct zero sequence impedance ? If the configuratin is "star" is the zero component 0+jX (where jX is the same as the positive and negative sequence components)? When I do this, my calculated values and the ones the computer spits out are quite different.
Any help would be much appreciated
Thanks






RE: generator - thevenin impedance
P.S. do not forget to consider the grounding resistance/impedance if any. Many programs would take this value as a separate input.
RE: generator - thevenin impedance
Which program are you using ?
Your zero sequence path at distribution levels will usually be dominated by transformer earth paths (either Neutral earth impedances or earthing transformers) close to the busbar.