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So, for extremely inverse curve the breaker will take less time to operate for the same amount of current, correct?

Both attached curves are different with regards to inverse and extremely inverse time characteristics for circuit breaker? which one is correct? noting that the first picture was extracted from Zach practice exam and I get the other graph from external source.

I got a question on the effect of reducing stator voltage of the induction motor, may I know how this reduction will affect rotor current and power factor of the system? thank you all for help,,,

Hi, I solved this question in different way by using transformer turns ratio but I got different answer, may I know why the second method is wrong? Thanks

thanks all for sharing very useful information..

Thank you all for help..

What I know synchronization is required when connecting two generators in parallel, one of the requirement before connecting two generators is to make sure they have the same voltage rating. My question, is it required to match phase voltage or line voltage together,. I see one question in...

What if the question (in NCEES#521) asks about the time delay setting if we supposed it is not instantaneous type? how can we get impednece value if zone 1 is located within 15% of line impedence.

Hi Gents, I tried to solve this question about two Wattmeter method, my answer to get W1 &W2 equations was in different from the answer given in the NCEES practice book, I know the answer is the same for both equations if PF=1, but I want to get the right equation in case if the power factor...

GREAT, thank you so much for your help

Hi Gents, Referring to the below example, when we multiply the secondary phase current in wye side by transformer turn ratio, shall we get phase current in primary (Delta side)?  Is given answer correct when he got on tge line current in primary after multiplication of turn ratio? 

During my preparation for the exam, I used to study from NEC handbook and I become familiar with its contents and its explanations but when I know that the exam provide us the NEC code not handbook I got confused 😰. I tried to solve many questions but I took time to get required section. My...

Congrats to all who passed the exam..  Hopefully I will join you next month. I have studied and I did a practice exams from different resources. My question to you guys how can I know if I'm on the right track and ready for the exam..  The exam is covering too many topics and after all times I...

When you go to Wildi Book for electric machine under autotransformer section, he states that voltages are added when H1 and X2 or H2 and X1 are connected. The voltages are su tracted when H1 and X1 or H2 and X2 are connected. is it general rule we can apply anywhere? what is the difference...

I got it.. thank you so much 

Thank you all for explanation and clarification, but why synchronous motor delivers reactive power while in equation (shown above) it is in negative which means in my understanding (when Q or P negative) it is absorbing instead of supplying power? 

Hello everyone.. The subject question is related to over excited generator. The answer in the book is (B).  But I when I tried to answer this question, my choice was (C) because it is over excited generator which means induced voltage is higher than terminal voltage. My understanding under...

Thanks for clarification.. to avoid confusion I would recommend to mention in the equation Vmax instead of Vline.

Hi,  I have noticed one comment in the reference book page# 65, I would like to share it with you before we escalate it to NCEES.  The equation to find the capacitance is C=Q/pi*f*(Square V) but if you start analysing the equation from reactive power you will get:  Q= (Square V)/Xc  where...

Thanks Zach, I really appreciate your efforts to teach engineers how to pass PE exam. Your sessions are very useful not only to pass the exam but also when we deal with electrical equipment in the field. Good luck!