# Symmetrical Components

April 8, 2013
I am an electrical engineer, graduating years ago. I forgot how to determine the symmetrical components and unbalanced fault using a five bus system with motors and generators on the five different buses. Could you please explain how to calculate the unbalanced fault for the five bus system?
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Q: I am an electrical engineer, graduating years ago. I forgot how to determine the symmetrical components and unbalanced fault using a five bus system with motors and generators on the five different buses. Could you please explain how to calculate the unbalanced fault for the five bus system?
John Grzesiak (USA)

A: John, I'm afraid this excellent question is a bit too complex to answer in the space that we have. However, several experts recommended references that can bring you up to speed. See below.

Paul Mauldin
Editor- Grid Optimization

Here's an excellent text book – Power System Analysis & Design by J. Duncan Glover and Mulukutla Sarma. I used this all through graduate school and it has excellent examples on how to use symmetrical components. I am still using it in my consulting work when I need a reminder.

Gene Wolf, PE
Lone Wolf Engineering, LLC

In addition to the text suggested by Gene, there is a text by Edith Clarke of GE - Circuit Analysis of A-C Power Systems, which is an excellent reference on Symmetrical Components.

Michael Bahrman
ABB

The text by Edith Clarke is considered a bible. She was the first female professor of EE at University of Texas.