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Oh, yeah, and thanks Josh for the info and link. Sorry ElecPwrPEOct11 I don't know how to answer your question yet. This is one of the last areas I am still trying to understand.

This bugged me for a while. What is happening here is NCEES is trying to trick you on 535. 525 is a straightforward autoXFMR problem where a single transformer is connected as an autoXFMR. The voltages are given and you can simply solve either using the proportional equations or by using...

Yeah, I guess you are right. I guess it just looks strange to me. I guess I wanted to see it in a book somewhere. I suppose it can be derived from the formula we are all familiar with: Q=root3(VLL)(I)sin(angle) -> substitute V/X for I and angle is 90degrees which then turns into Q=root3(V^2)/X

Ok, so p.f. correction is supposed to be a gimmie question, and I thought I had this nailed down, but apparently not. From what I can tell, the NCEES problems stop once you determine the VAR necessary to raise the p.f. I found a problem that wants the total capacitance. It is Camara sample...

And this is basically what Grainger/Stevenson says, and you know how much he/they love to go into extreme detail on problems. I guess it's a pretty safe assumption to make then.

Question: Do we assume the lines are transposed and therefore ignore separate calculations for mutual inductances? ETA: Ah, I see what you did. I hope to have an answer for you shortly. ETA: I got 25.09 ohms which comes to 0.0079 pu. Even though I don't think this type of problem will be on...

Sorry everyone, I did some more research and I have to correct what I posted above. It turns out that there is only cancellation if the three phases are all equidistant from each other in an equilateral triangle formation. Otherwise there is different mutual inductance between each pair. I...

Right. The chances of it being on the test are slim, but as you said it is not difficult so therefore is not a bad time investment IMO. I have the Grainger/Stevenson book, just not with me at the moment, but I will take a look when I get home. I did notice, however, that Camara p. 38-8...

I don't know if this will help you, but I do lots of studies with software at work. I'll explain how I understand it. It is not really a bus, but it is a generator or utility source. Every system has to have at least one slack bus (we call it swing bus) which does just like it sounds...it...

Thanks for pointing that out, I hadn't noticed before that those two equations only differ by a factor of two (and of course the distance vs mean distance). I suppose that confirms my assumption. And yes, it seems that you never get away with using the values from the table without that...

The examples I have been able to found (Camara) and others all use this table for a single-phase system, even though it is intended for 3phase. It just seems strange to me that the same values can be used for either system. Unless someone can tell me differently, I'll just assume that the...

I'm having some difficulty understanding how to use this table of standard transmission lines in the Yarbrough/Camara book (the one with the code names like Waxwing, Partridge, etc... It gives inductive and capacitive reactances for 1-ft spacing. How does this differ for single-phase vs...

Thanks EEVA. I am almost to that section in the lectures.

I mostly use IEC at work so I am not very familiar with NEC, so I have this question. It seems to me that NEC 430.24 says that the conductor ampacity for at least 1 motor + anything else has to be 125% FLC of the largest motor + the sum of 100% FLC of each of the other motors, "plus the...

I guess Camara is just oldschool then. I have that Wildi book, I'll take a look. Thanks for the responses.

Thanks, this certainly helps.

This problem seems to be a fault analysis problem, however I don't feel that I have the knowledge yet to solve it. I generally solve short circuit problems using the MVA method outlined by Moon H. Yuen ("learn it in an hour, use it anywhere, memorize no formula" available through IEEE industry...

I am pleased with these videos, especially the 3rd one. Thanks for sharing them. About the issue with the direction of rotation, this is how I think of it (and please correct me if I am wrong): If you mentally rotate the phasor diagram CCW, you should eventually see "ABC" pass through the 0...

So is our conclusion that the cable is not sized properly, resulting in too high of a voltage drop? To me, 14V makes sense for starting, but not for running. ETA: I guess you mean that the impedance and voltage drop numbers don't make sense relative to each other, but using the load current...

Thanks for posting this. I just thought of a question. I am tempted to simply assume the voltage across the cable is 117V-102.96V = 14.04V, but assuming your answer is right, then it must instead be IR = (11.56)(0.1) = 1.156V, and can also use V^2/R, or IV to get the power in the cable. I...