Line-Line Fault Circuit: Parallel or Series?

[Physicist3]

Hi,

When calculating a line-line fault, I understand that the Positive and Negative Phase Sequence networks are placed in parallel with each other as shown in the first attached image, and that the zero phase sequence is excluded. Although this is connected in parallel, does it not produce a series circuit such as the one shown in the second attachment?

 

[Greg Bernhardt]

Thanks for the post! Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?

 

[zoki85]

View attachment 75220 Hi,

When calculating a line-line fault, I understand that the Positive and Negative Phase Sequence networks are placed in parallel with each other as shown in the first attached image, and that the zero phase sequence is excluded. Although this is connected in parallel, does it not produce a series circuit such as the one shown in the second attachment?

View attachment 75221

As you said, equivalent positive and negative phase seq. networks can be placed in parallel when considering this fault. However, this doesn't produce a series circuit of all the impedances fed by emf "e" since currents in different parts of new network are generally different (i₁≠i₂≠i_f).BTW, if you calculate in p.u. system, all voltages,currents,impedances must be in p.u., and denoted in small letters. I have modified your schematic accordingly: