I know that the total harmonic distortion (THD) in a power system with n harmonics is calculated by the below equation:
THD=\$\frac{\sqrt{(V_2^2+…+V_n^2)}}{V_1}\$
but what about any single harmonic? Is it true that calculate harmonic distortion specifically caused by third harmonic (for example) this way?:
\$3^{rd}HD=\frac{V_3}{V_1}\$
if it's incorrect then, how to calculate it?
Best Answer
The THD formula you have looks wrong to me so...
The RMS of all harmonics \$\sqrt{V_2^2 + V_3^2 + ... V_N^2}\$
Then this is divided by V1: -
THD = \$\dfrac{\sqrt{V_2^2 + V_3^2 + ... V_N^2}}{V_1}\$
This now makes sense because it's the ratio of two voltages - you had V1 within the sq root area and this is wrong.
So, to answer your question, yes the 3rd harmonic distortion is \$\dfrac{V_3}{V_1}\$