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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

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...

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? 

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...

Hello,  As most of you aware that the PE Power Exam will be in form of CBT starting from Jan 2021. Due to that transition, no external reference will be allowed during the test and only NCEES reference book, which will be published officially by NCEES coming July,  can be used. From this moment...

Hi Gents, I need your help to get the following references for PE Power Exam. I tried to look for them in many libraries in the KSA but unfortunately I couldn't find them. I can negotiate with the people who have these books on the price. Complex Imaginary 1,2,3,4  Power System Analysis Book...