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If Vrms= Vmax/2 per the Wikipedia and PPI, then why NCEES problem 515 is using Vrms= Vmax/ sqr2? I am not sure which one to believe.

Thank you

In NCEES problem 510 there is enough information to find what the FLA is but the book still used the NEC value. Is that because the problem did not specifically mentioned the amount of the full load current?

in this case the full rectifier and half rectifier Vmax both will be calculated the same way. (Vmax = Vrms X sqr2). Is that correct?

Is the Vrms to Vmax in HWR is (Vrms= Vmax/ sqr2 )or (Vrms= Vmax/2) I see in PPI book page 27-6 the second formal and on NCEES problem 515 the first formula. Thanks

Hi there, Question to the one who are expert in NEC! to calculate the size of overload protection device for motor, we use the currents listed on table 430-247 through 430-251 plus additional percentage of the currents depends on what type of motors we work with. What I don't understand is...

Thank you. That helped.

KatyLeid, Here is problem 10: A 60HZ, three phase, 208V system carries a total load of 200+j150VA. What is the most nearly the total capacitance required to correct the power factor? The PPI answer is: to find Xc Q=sqrt3 X(V2 /Xc) to find C C = (-1/2 x pi x 60 x Xc) It is so confusing...

Hi there, I have a new delema, what is the equation for Reactive power with respect to voltage and reactance? There are two question in PPI power sample exams (P10, P12) which the Q is calculated and the book used (Q=(sqrt3)x(Vsquare/Xc). I think the formula should be Q= (Vsquare/Xc). Please...

Hi KatyLied, Sorry for late respond. I was gone for a while and just checked the website. Here is the problem 6: A delta-wye transformer is rated for 34.5kv/480v, 125A primary current(L-L). What is the transformer's power rating(KVA) and the secondary current. The book asnwer is...

Hello there, I don't understand problem 6 in volume 3 of Complex Imaginary. Why s = vI and not S = (sqr root of 3)xVxI? The book says because of delta and Y connection but we consider 3 phase system which it should be the same in delta and Y. I appreciate your comments. Thanks

I do not see any failing which is a good news but I was wondering if they first sending out the one who passed the test?

Any news from CA?

Anyone in CA got result?

Thank you that was a big help.

I agree, exam cafe is just wasting money. I tried it.

Hi There, Does anyone know the answer for question below? two transformers are connected in parallel. both have delta primary and wye as secondary. That means delta connected to delta and wye is connected to wye. Is this connection okay or it will cause circulating current? I appreciate...

Thanks a lot for the respond.

Hello there, Can any one tell me what happens if in 4 wire three phase wye connection, one of the phase completely get diconnected? Thanks

You are way ahead of my as far as studying. Thank you for explaining about the mini exam. I have two books of CI. They have good problems but there are also lots of mistakes in the books.