Graffeo Example 50

Why is the per unit impedance for Zt2=j1 not put in parallel with 0.2+j0.546? There really is no explanation to problem other than picture or I would put it down also.

The fault between XL and XT2 puts anything beyond the fault (in this case, XT2 and Xm) in parallel with a short to ground. An impedance in parallel with a short to ground will carry virtually no current since the current will all travel down the short (the path of least resistance).

Okay so on example 49 why did they do it for the negative sequence? 

ask Alex the difference 49 and 50, here is the reply:

Yes, It is because it is a 3 Phase fault.  In the most recent printing I added a note:

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[SIZE= 7.5pt]With that assumption, there would not be a negative sequence component for the 3-ph fault and we get:[/SIZE]

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[SIZE= 7.5pt]Also, in case it's not in your version I'va added this note also:[/SIZE]

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