Trabsformer diagnostics-FRA

[00123456]

Dear All,
I am just starting new thread with some question for transformer diagnostic by using frequency response analyzer.

1) What are the difference between low impulse & sweep freq. method?

2) Is the sweep freq. method is more precise than impulse method?

3) FRA & Tan delta test are sufficient to carried out during routine test?

4) Is FRA test is require during routine test? If it is yes then why? if is no then suggest period to check FRA test for TR.

Thanks

 

[ozmosis]

Most of your questions are answered in this article:

http://www.eet-d.com/article.asp?m=5&mag=19&article=145

 

[00123456]

Hi,
Thanks for sending link.

As per my knowledge;

Advantages of Sweep response method are;

1) High signal to noise ration. This comes from using filtering function of the network analyzer to remove broadband noise.

2) It is possible to use a finer freq. resolution at low freq.

3) Only one piece of measuring instrument is required

Disadvantage:-

1) Only one measurement can be done at a time.

Advantages of Low impulse method are;

1) Several transfer function can be done simultaneously

Disadvantages:-

1) Freq.resolution is poor at lower freq.

2) It is difficult to filter out broadband noise.

3) The amount of power injected in to the test object is differet at different frequencies. This leads to differences in precision across the freq. range.

3rd & 4th questions are still unanswerd.

Thanks

 

[ScottyUK]

Another good article.

http://www.electricity-today.com/et/issue0601/i06_ryder.htm

An ex-CEGB engineer called John Lapworth did a lot of development work on the FRA technique. Last I heard he was with Doble somewhere in the UK. Might be worth a call.


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Sometimes I only open my mouth to swap feet...

 

[ausphil]

00123456

The following link is to a Doctoral Thesis by Eilert Bjerkan, who has done a lot of work in modelling transformer windings and cores, transformer faults, and comparisons of methods of FRA.

Be aware that the pdf is about 6MB and some 260 pages long.

http://www.diva-portal.org/diva/getDocument?urn_nbn_no_ntnu_diva-622-1__fulltext.pdf

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Congratulations must go to Mr (hopefully now Dr) Bjerkan for the work he did here.

Ausphil

 

[00123456]

Dear All,
Thank you very much for Providing details.