# ask about vfd



## ron77 (Feb 14, 2011)

can any one help me? pleas.............

i need any material for vfd

i can't pass the exam with this part :bananadoggywow:


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## cableguy (Feb 15, 2011)

Go to NEMA.org and download their free paper on AC Adjustable Frequency drives. It does require registration (I used a disposable email address), but it's free.

http://www.nema.org/stds/acadjustable.cfm

I did use it during the exam, and it did have the answer.


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## ron77 (Feb 16, 2011)

cableguy said:


> Go to NEMA.org and download their free paper on AC Adjustable Frequency drives. It does require registration (I used a disposable email address), but it's free.
> http://www.nema.org/stds/acadjustable.cfm
> 
> I did use it during the exam, and it did have the answer.



tank's so much

i'll try this link


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## ron77 (Feb 16, 2011)

i can't download this file but i found it in anthere link

can you look at this link and tell me if it the same or not

http://www.sea.siemens.com/us/internet-dms...e%20Systems.pdf


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## cableguy (Feb 16, 2011)

No, the NEMA document is like 80 pages long. That document you reference is a little of the info, but there's a lot more in there.


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## Dolphin P.E. (Mar 16, 2011)

cableguy said:


> No, the NEMA document is like 80 pages long. That document you reference is a little of the info, but there's a lot more in there.


I think they have the Speed Regulation Formula wrong. They are mixing between Speed Regulation formula and Slip formula. take a look at section 6.3.5.2 "Speed Regulation".


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## EDISON_NY (Mar 17, 2011)

if you remember which page was the answer, I took the oct-2010 exam and didn't pass, and this part was killing to me....



cableguy said:


> Go to NEMA.org and download their free paper on AC Adjustable Frequency drives. It does require registration (I used a disposable email address), but it's free.
> http://www.nema.org/stds/acadjustable.cfm
> 
> I did use it during the exam, and it did have the answer.


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## cableguy (Mar 17, 2011)

I won't point to the page (too specific  ), but section 5.3 (7 pages) had some good information in it.  If you can remember the question, you'll spot the answer while reading.

But I doubt they'll ask the same question again.

But I'd seriously at least skim that whole document, it does give a really good overview of VFDs, plus the table of contents is well laid out and could be helpful.


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## EDISON_NY (Mar 17, 2011)

Thanks,


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## jeanbj2000 (Mar 28, 2011)

cableguy said:


> I won't point to the page (too specific  ), but section 5.3 (7 pages) had some good information in it.  If you can remember the question, you'll spot the answer while reading.
> But I doubt they'll ask the same question again.
> 
> But I'd seriously at least skim that whole document, it does give a really good overview of VFDs, plus the table of contents is well laid out and could be helpful.


CableGuy, do you think the entire section 5 is enough for VFD questions on the exam?.

Thanks!!!


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## springaround (Apr 3, 2011)

is this the same document?

https://mail.nelson-electric.com/webshare/E...cadjustable.pdf


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## cableguy (Apr 4, 2011)

The version I had from NEMA looked slightly different, but that looks like the same content. So yes, that'll do.

And as for 'just section 5', I have no idea. They could pull something from another section easily. I took the whole thing in with me. The Table of Contents is as important as the rest of the text, just to find things quickly.


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