Hi guys
Going through an example here of a power fault. There's a matrix on page 3 with a variable cited as "a" and I can't work out for the life of me, what it is.

The document I'm working from is some type of PDF with funny formatting, for some reason it keeps repeating words 3 times when I copy paste? weird, so anyways I'm just gonna upload a few screenshots instead. I've circled the bit I'm interested in in red. I've uploaded all 3 pages, including the 2 pages before my issue, for your reference.

 

Try to solve for the variable 'a' given the numbers available. There are two quadratic equations implicitly here, each with 2 possible solutions for 'a'. The two quadratic equations share a solution (within rounding).

 

While I understand it's not always good to give students answers, rather to make them work for it, so they learn - this isn't something I need to learn. What I do need to learn is how to repeat this sequence, plus another 4 pages or so, after it. Multiplied by a million other things I might add... But to learn how to do this type of analysis I just need to know what "a" is, not how to calculate it. If you'e figured out what "a" is, can you please tell me. Thx

 

Hi guys
Going through an example here of a power fault. There's a matrix on page 3 with a variable cited as "a" and I can't work out for the life of me, what it is.

The document I'm working from is some type of PDF with funny formatting, for some reason it keeps repeating words 3 times when I copy paste? weird, so anyways I'm just gonna upload a few screenshots instead. I've circled the bit I'm interested in in red. I've uploaded all 3 pages, including the 2 pages before my issue, for your reference.

View attachment 150085 View attachment 150084 View attachment 150083

Hi there,

'a' is the unit vector with angle 120 degrees. So a=-1/2+j*sqrt(3)/2.

Usually when we see something like this in a matrix it is a voltage or current ratio, but i would think that the book or whatever reference you are using should point out where they got that 'a' from, and why they are using it. It doesnt make any sense to spell out a matrix with a variable in it yet never say what that variable is or why they are using it. If that happens to be the case however, you'll need a better reference. Perhaps a decent electrical engineering handbook.

Usually when a book uses a variable like that they dont always spell it out in the same chapter, but they usually do spell it out in a preceding chapter so check there if possible.

 

Yeh correct MrAI. I went and seen the lecturer. A = 1 /_ 120 degrees
A^2 = 1/_ 240 degrees