Recent content by mull982

I passed the first time in FL! Thank God thats all over with. Time to party

I would also like to thank everyone on this forumn for all their support and explanations the months leading up to the exam. I was able to pass my first attempt and I attribute alot of what I knew during the exam from the discussions and teachings here on this site. Thanks again also to Dark...

Thanks thats what I thought, I just didn't want to get confused at the last minute. If you have two transformers with different rated MVA's then you can even choose a 3rd arbitrary MVA as the base as long as you convert both transformers to the third base. Isn't that correct?

When you are given a piece of equipment and told its actual paramaters are those paramaters always taken as 1 per unit for the respective voltage, VA, and current? For instance if we have a 10MVA generator, rated 13.8kV, 418A, is the rated voltage, current and VA equal to 1.0 where 1.0 pu...

I simply used V^2 / X to find the total system reactance, where V^2 is equal to the phasor VA-VB. Is this a correct way of doing it as well, or is this just a conincidence? Also when using VA-VB/X to solve for current and then using I^2 *x to solver fore reactance works when using the L-L...

To look at this even further I put some numbers to problem 509 in the NCEES exam to try to solve for the power factor. Lets say that in problem 509 we have the same connections that are shown but we are told that W1=800W and W2=400W and we are asked to find the power factor assuming the sam ABC...

O.K. after looking at it heres the way I see it. using tan(theta)=1.73 (Wc-Wa)/(WC+Wa) Wc is always the power meter that has the cos(30-theta associated with it) Depending on the phase rotation this will be WC for ABC rotation, but for CBA rotation this will be Wa. So ingoring the subscripts...

I always use the forula Z=Rcos(theta)+Xsin(theta) for this type of problem. My question is why did their solution not factor in the power factor angle for theta for the effective Z value? They simply used the R and X values given from the table. Dont you have to use the power factor angle for...

Aaaahhhaa! The light bulb just went on! Great example this helped me see whats going on very clearly now. Thanks for the help!!!

When looking at example 1.1 in Power System Analysis by Grainger I notice that the give the Apparent power equation to be S=VI*. In example 1.1 they use the apparent power calculated for S1 to be S1=V(-I)*. I believe this is because I has a direction that is different from the source...

If you would have used your method and used WA-WC then you would come up with an answer of .8 lagging as opposed to the .8 lagging they give in the solution.

Does anyone know why they used P2-P1 instead of P1-P2?

O.k. that makes sense. I see how this arrives at the solution using the voltage yb. The only part that isn't jiving with me is why we use Vbc for adding to vyb? I see that this makes sense in the equation using doulbe notation but is this the only reason we choos this? Because I just cant...

O.k. that is starting to make a little more sense. So with double subscript notation the inner terms out of the group of 4 terms cancel (in this case the b's) and we are left with a vector consisting of the outside terms? Is this the same for subtracting vectors as well? This may be where my...

Can someone please help me identify what I am doing wrong with understanding the phaosor notation above? It is driving me nuts