EE's Guide to PE Power error?

[thebard]

I am looking at page 16-17, where it has the phase currents Ia, Ib, Ic for delta connection. It says the line currents lag the phase currents by 30 deg on pg 16, but the equations on pg 17 look like the line currents are leading the phase currents by 30 deg. It has for example Ia = Iab * sqrt3 * angle30deg.

Please help, thanks.

 

[rg1]

I am looking at page 16-17, where it has the phase currents Ia, Ib, Ic for delta connection. It says the line currents lag the phase currents by 30 deg on pg 16, but the equations on pg 17 look like the line currents are leading the phase currents by 30 deg. It has for example Ia = Iab * sqrt3 * angle30deg.

Please help, thanks.

IMHO if the sequence is A, B, C and Iab<0, Ibc<-120, Ica<120 are phase currents in Delta then IA=Iab-Ica will lag 30 degrees to Iab. However in case Voltages in Star the line Voltages lead the phase Voltages by 30 degrees. 

 

[KatyLied P.E.]

I'll have to look at that one later but for what it's worth the author is good about responding to questions.  His email should be in the book or on the website.

 

[thebard]

Nevermind, found an errata on the book website. http://powerpeexamguide.com/about-the-power-p-e-exam/errata.html

It should be negative like I thought.