# Symmetrical component equation question.

#### mbohuntr

Joined Apr 6, 2009
446
I may be taking a class in protective relaying soon, and need to get a jump on the math since I'm no engineer. The attached link shows Fortesque's theory in matrix form on page(s) 2 and 3. If anyone has the time, could they do a calculation using imaginary voltages? I am beginning to understand the "a" operator, but maybe if someone were to write out a complete calculation using TEX, I would grasp it easier. (I tried TEX, and haven't got it yet.) I do understand the concept of positive, negative and zero sequences, I just can't seem to put it together in any coherent fashion. (The equation doesn't have to follow the matrix method, It might be easier to calculate individual phases like the middle of page three.) I guess I don't understand the process or the goal. Thanks a LOT, this will be a lot of work. Mike

http://www.ece.umd.edu/class/enee474.F2003/PDF%20Files/chp10_1.pdf

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#### t_n_k

Joined Mar 6, 2009
5,455
I'm not clear on what you want.

Do you require a worked example of how you get from the unbalanced 3-phase set to the symmetrical component equivalent set? Surely that's what the (attached) document writer has already attempted to demonstrate.

What's the relevance of your requirement to have it written in TEX?

#### mbohuntr

Joined Apr 6, 2009
446
Yes, for some reason I can't wrap my head around the process as well as the result. I understand adding the zero sequence component vectors to obtain zero current on the neutral, but I am not clear on what to do with unbalanced components. I figured if someone came up with some imaginary phase voltages, and worked the problem, it would become clear to me. No, this isn't homework, I already graduated. My math skills are weak when equations are concerned. Thanks, Mike (It doesn't have to be in TEX, but that comes out the clearest. )

#### subtech

Joined Nov 21, 2006
123
I may be too late in getting here...

I can't help with the matrix math, but I can walk you through a practical example using simple numbers. If that would help you, post again and we'll give it a go.

Mke

#### mbohuntr

Joined Apr 6, 2009
446
Absolutely! Understanding the goal would be just as good as the traditional approach. I work in a generating station, and would like to bid into a better job. Protective relaying seems to be the gold ring as far as training goes, so if I get that, it would make the resume shine... Thanks.

#### subtech

Joined Nov 21, 2006
123
Okay then. I'm glad you told me you work in a power plant. We will proceed using examples that are specific to devices found in a power plant.
I'm going to do this in stages because my time is limited due to my work situation at the moment. Also, I'm not familiar with TeX, but I'm willing to try it. If you've got the patience to wait on me, I'll do my best.

Note: Relay technicians are well trained because they MUST be. Making mistakes when working on relays that protect large generators is very, very bad.

Have you had any classes/training with symmetrical components, or are you studying on your own?

Mike