# VFD's, Ring Bus, Breaker and a half, AutoXfmrs and more needed resources



## [email protected] (Oct 14, 2012)

Hello Gents,

I'm preparing for the Oct. 2012 Electrical PE using the compledx imaginary and NCEES practice exams and I've found I don't have good resources for the following:

-VFD's

-Ring Bus, Breaker and a half configurations

-AutoXfmrs

-locked rotor currents

-lighting calcs

I expect the lighting and locked rotor current resource should likely come from the NEC 2011, but as I've never used that in my experience as an engineer I'd appreciate any guidance on a good place to gain some understanding.

Thanks for any help and good luck to the rest of you studying!

- Larry


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## katag (Oct 14, 2012)

Do you have any of the books that people suggested as good resources? The Wildi book has good information on Autotransformers and a section on Power Electronics that has some info of VFDs. The Chelapati book also has good information on Autotransformers. The Wildi book is full of valuable information. From my studies I would say for the most part the Locked Rotor Current does come from the NEC. I would just be familiar with table 430.7(B) and 430.251(B) in the NEC and the theory behind it.

For lighting Calcs I would google search "lumen method" and "zonal cavity method" and have those handy for the test. From all the practice tests I have worked out, the lumen method gets the job done.

For breaker configurations I would just do a google search and see what you can find. I don't have any information on that specifically but throughout my study process I have found tons of good information online. I will probably search this online as well and print out something just in case.

Oh and we aren't all "Gents" on here. Although few and far between there are some ladies =)

Hope some of this helps! Good luck!


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## [email protected] (Oct 14, 2012)

Haha busted ... Ladies and Gents in that case.

I'm using the Camara prep book, Grainger power system analysis, Chelapati (though I haven't used it much) as well Goetze - Intro to power systems, NEC2011 and Ugly's.

It is probably too late in the game to get Wildi. I'll have to find a sub for that.

Thx


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## knight1fox3 (Oct 15, 2012)

+1 for the Wildi book. Good resource to have for the exam. Power System Analysis &amp; Design by Glover/Sarma/Overbye is another good reference to have.


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## ruffryder (Oct 16, 2012)

I found lighting calcs on the net, just make sure to double check them as I found some errors in the calcs for zonal caveties.

Locked rotor currents come from the NEC

Autotransformers any power systems book should have some info on it. Work the problems so you know how to do the calculations

Bus configuration and breakers, probably search the net for it

VFD's, again, search the net if you aren't going to be buying a book.

I am taking the test in a couple of weeks as well. Good luck to us!


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## cableguy (Oct 16, 2012)

For VFD's, Google:

NEMA Publication, Application Guide for AC Adjustable Speed Drive Systems

Find the 81 page document (PDF) (third hit on Google for me)

Print it out, stick it in a binder and bring it.


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## ruffryder (Oct 17, 2012)

Thanks cable guy,

To add some contribution see these links.

substation breaker configuration
/&gt;http://www.ee.iastate.edu/~jdm/ee653/SubstationReliability.pdf

protection
/&gt;http://eppe.tamu.edu/k/Chapter.pdf

lighting
/&gt;http://upupaepops.files.wordpress.com/2008/02/zonal-cavity-method-for-indoor-calculations.pdf

lighting formula's
/&gt;http://www.lightsearch.com/resources/lightguides/formulas.html

XXXXXXXXXX Note XXXXXXXXX

The light search link has some errors in the formula's for Zonal Cavity. The numerator should ADD Length and Width, NOT MULTIPLY. The lumens method seems correct. I have not verified the other forumula's. The other link above seems to be better.

Anyone have any good consice references for power electronics (mostly components and functions?). that can be printed out? I have an electronics book and a power electronics book, but I am looking for something that has some fundemantal calculations and or theory. Maybe I don't know what I am talking about.


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## knight1fox3 (Oct 17, 2012)

cableguy said:


> For VFD's, Google:
> 
> NEMA Publication, Application Guide for AC Adjustable Speed Drive Systems
> 
> ...


Whoa! cableguy is alive!


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