Graffeo Example 50

[Dodgeviper1017]

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.

 

[jmitch23]

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).

 

[Dodgeviper1017]

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

 

[AAGR2013]

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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