Symmetrical Components

[Bruno]

To all:

Anyone have any ideas about the types of questions involved here? I've gone through the GA Tech Prep course and this is presented in a very condensed manner - I don't do these calculations at work and depend on SKM Power*Tools if I should have to. Anyhow, the CI practice test offers only general (i.e., thematic) questions on this subject. I'm waiting to plow through the NCEES practice exam this weekend to see what I encounter and, what I've learned, so any advice is appreciated. Putting some of these transmission circuits into there positive, negative and sequence components is probably the biggest challenge I've had in prepping for this ***forsaken exam.

Bruno

 

[Wheretostart]

It is used a lot in fault calculation, and basically solve the unsymmetrical fault problems with symmetrical component equations. Most of faults are not balanced.

 

[daw4888]

If you understand why you use Symmetrical Components and the theory behind them, I would not waste a ton of time studying it if you are having issues.

Its really simple once you understand it. Basically you put a transmission system into a P.U. single line diagram. To do this you need to settle on a system MVA and voltage. Once you do that, its just calculating the P.U. impedance of the lines and transformers. Once this is done then you draw the diagrams. Make sure you have in your notes how to draw the various different zero sequence transformer diagrams.

Once you have a oneline diagram, you just do normal circuit rules to combine all the impedance between the generator, and the point of the fault(defined in the problem), and then to get the fault current you take 1.0<0 (unless defined as something like fault voltage is 10% above normal voltage, then you would use 1.1pu ect..) and divide it by the impedance of the circuit.

 

[Dark Knight]

Just focus on the basis. The test will not throw you a curve ball. Review the basic concept and be sure you understand it 100% and you should be fine.

 

[Bruno]

Thank you for all of your responses. Your support is appreciated!

I'm nearly there with it, working on drawing the diagrams at this stage.

Bruno

 

[Sizer]

Hi Bruno here is a link that mght help you understand the concept better: https://www.youtube.com/watch?v=dqXDZfzmhh8

I hope it is of help.

Regards

 

[Bruno]

Very clever routine. Thanks, as visuals always help me. If only I could take an iPad into the exam...

Bruno