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The PF is defined as the relationship between the voltage and current phasor. Therefore when doing a source transformation you need to rotate the current phasor with the voltage phasor as rg1 said above. The way the practice test authors work these voltage problems they just don't rotate the...

I have PSA by Grainger/Stevenson, EoPSA by Stevenson, PSAD by Glover et al. I find these books too academic for what I need, except EoPSA.  But I work in this area (protection of transmission) and I think practical implementation is clouding what I need to know for problems in that area...

I'm not finding the Spin Up practice exams a very constructive use of time. For example it asks "what voltage class is 13.8kV"  Low, medium, high, extra high, none of the above (don't get me started on this option) Well the only place you will find these arbitrary classes is in company...

How do you combat burnout? I started early but I'm having trouble keeping on it.

All the sample tests seem to disagree with you. This is a voltage drop problem. That is an autotransformer problem. Is this a bad way to prepare for the exam? The only way to grasp the concepts is to continue drilling, in my opinion.

This effect can be observed with only one phase energized, according to this document: http://www.swedeus.org/SWEDEpdf/2010/Voltage Backfeed on D-Lines - Oncor -TDM.pdf This is not an intuitive effect.

I also don't work on distribution systems. But this is an interesting question that I would have got wrong. I was assuming 1/3rd of the customers would get dropped. Just goes to show don't assume on the exam, always check your references or actually solve the problem schematically or numerically...

CI Test 4 Problem 9 is an unfaulted condition, but its base value is taken to mean line to line voltage and is divided by sqrt 3. This is the problem I mentioned earlier.

I think rg1 is correct. There is an identical question in CI that solves it by dividing the base voltage by sqrt 3. I will point out the discrepant questions when I get home.

I think I should order a copy of Blackburn for after the Exam. I hope it doesn't just fill the pages with matrix manipulation like Power Systems Analysis by Grainger and Stevenson.

What's the best resource for this intuition of modeling faults? The books either don't go enough into detail or see the problem as a good excuse to practice matrix computation. Are there professional seminars on this subject which don't involve going back to graduate school? I'm don't need...

Thank you very much rg1! Your derivation is very helpful. I will look in the Wildi book. I have not used it much and can never find what I'm looking for in there. This is from CI Test 4 Question 78 in case anyone is wondering.

I think a similar statement of the formula is in this SEL paper, formula 1: https://cdn.selinc.com/assets/Literature/Publications/Technical Papers/6250_ApplicationExisting_JB-KZ_20070214_Web.pdf?v=20160511-160915 This is the change of base formula  But there is a twist. Why is Z,PU,given...

My question is where does this formula come from? Additionally this formula: Isc = (Transformer KVA) × 100)   (√3) × (Secondary KV) ×  [(%Ztransformer)+(%Z Utility)] I get the feeling because I dont understand this there are still some concepts of...

I'll post the exact question from CI when I get home, but I had a problem with calculating the source impedance of a utility. I found a link with the formula. http://iaeimagazine.org/magazine/2015/07/07/calculating-short-circuit-current/ The link says the source impedance is  %Z Utility...

You can use the XFMR formula for CTs, but you have to think about it first. This is how I do it: The transformer formula is Np * Ip = Ns * Is If you plug in the ct ratio numerator for Np and denominator for Ns you are going to have a bad time! Realize that Np = 1, because the primary...

She was talking about a question on the actual PE exam. Please be careful because you could get someone barred from being a PE forever if they answered your question. We cannot discuss the Exam content, we signed an agreement.

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I think the convention for these equivalent circuit of an AC generator problems is that Eg is the line to neutral voltage of one terminal.  Please see this image from Elements of Power System Analysis by Stevenson I think CI is right for this problem as long as you agree the...

I have the same problem with this CI Exam 3 Problem 34. What is the clue that the generator has been short circuited? Is it because the current is called "steady state?"