Negative X/R Ratio: Aspen Model

[snerts50]

Good morning,

I was surprised to find my model showing a negative X/R ratio this morning when using Aspen to model some faults.

Any thoughts on this? I am a bit confused as to how it occurred...

Thanks
Caleb

 

[Skogsgurra]

False polarity somewhere? Negative X/R usually means capacitor. But that isn't it - is it?

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[magoo2]

With a three winding transformer, you often wind up with a negative branch for one of the reactances. Depending on where you are in the system, this could lead to a negative X/R ratio.

 

[snerts50]

I double checked my impedances, and found nothing negative, everything looks to be properly entered into the program.

I didnt add any new three winding transformers, though I did add two new two winding transformers. And when I take the new portion of the circuit I added out of service, the X/R returns to a positive value...

Could small enough X values added in parallel create a negative X/R? Meaning, Or maybe the phase angle is causing this, since this is a complex value of the impedance as seen by the fault?