# Present Harmonic Distortion

Discussion in 'Homework Help' started by max1x10tothe6th, Oct 26, 2010.

1. ### max1x10tothe6th Thread Starter New Member

Oct 26, 2010
2
0
hey guys,

Need help finding present harmonic distortion.

the problem states we have a 750kva transformer at 60hz running 480 3ph with 5.75% impedance.

i found FLA to be 477A.

Effective impedence is 3.04%

the question asks: Estimate the present harmonic current distortion based on FLA and Efective impedance.

any suggestions or comments would be greatly appreciated.

or even a general equation would be awesome.

2. ### t_n_k AAC Fanatic!

Mar 6, 2009
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How did you arrive at FLA=477A and effective impedance =3.04%?

3. ### max1x10tothe6th Thread Starter New Member

Oct 26, 2010
2
0
FLA came from the NEC codebook.

3.04% impedence came from Z(effective)=Z(xfmr impedence) x actual load/ xfmr rating

actual load came from s= sqrt3(V)(I) which is 477(480)(sqrt3)

4. ### t_n_k AAC Fanatic!

Mar 6, 2009
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782
Presumably from your FLA value the stated 480V is the line-to-neutral voltage?