# VFD sections in Wildi?



## DMB5mil (Jul 22, 2008)

I've heard from several sources that VFD's need to be reviewed for the test. I've also heard that Wildi's 'Electrical Machines, Drives and Power Systems' is a good source to study VFD's. However, due to my lack of experience with VFD's I'm having trouble pinpointing which chapters in the book to study on this subject. VFD's aren't listed in the index and there seem to be several chapters that may or may not be applicable. I guess I'm not sure what all consistutes studying VFD's so I need help identifying applicable chapters.

Thanks for your time,

Brian


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## wilheldp_PE (Jul 22, 2008)

If they are on the exam, they must either be in the Power or ECC depth portions because I didn't see them in the morning or Computer afternoon sections. That's a shame, because I know quite a bit about VFDs.


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## mudpuppy (Jul 23, 2008)

VFDs called out in the specs for the Power depth module. I don't have the Wildi book so I can't help on this one. I try to avoid electronics in general.


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## Techie_Junkie_PE_LEED_AP (Jul 23, 2008)

Well, in the Table of Contents Part III is called Electrical and Electronic Drives in big bold letters. 

Study all of Part III and know it. Pay close attention to PWM and power electronics.

Good luck.


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## mudpuppy (Jul 23, 2008)

[SIZE=12pt]Just to offer a different opinion. . . .[/SIZE]

I personally didn't study power electronics at all due to its low weighting on the exam content, the limited amount of studying time I had available, and my almost complete lack of knowledge on the subject. It probably would have taken me a week or more even to get a passing familiarity of the subject and I didn't think it was worth it for one or two questions.

However, there is still plenty of time before the October exam, so go for it if you want to.

The point I'm getting at is make sure you use you your study time efficiently based on your own strengths and weaknesses as well as your available study time.


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## DMB5mil (Jul 24, 2008)

Thank you for the advice and encouragement!

Brian


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## Texass (Oct 13, 2008)

its listed under 'speed control' in index


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## Kuku (Oct 14, 2008)

Texass said:


> its listed under 'speed control' in index


Other than RPM = (120xf)/p, what else is there to know about VFDs mathematically speaking? Would it be important to know the intricacies of the constant voltage or constant current types?


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