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**jatin333 said: **

up what extent voltage and current harmonics acceptable?

what are effects of current and volt harmonics in system?

Dear Mr. Jatin333 ;

refer to your question and the reply of Mr. Alen, I want to clarify some points :

1 – We know all that the path of any current either Fundamental or Hamonic current is from the load to the source, that means **there's no any direct effects** from the harmonic currents on the other loads, but, the harmonic currents with the harmonic inpedance of network are reponsable to have a ” Voltage Distrotion ” in the network, and that **voltage distortion has a direct effets** on the loads even the linear-loads. So, the effetcs of the harmonics current is, as Mr. Alem said, on the : Cables, Transformers, Generators, Motors, Capacitors, ext. where there's many solution for that.

2 – Normally, as the direct effects on the load is from ” Voltage Distortion ” we should look to the percantage of Voltage Harmonic that means ” THD U or THD V “, and when these values exeed some levels, we should find the suitable solution for the network, else we will have problems with some sensitive equipments. Noting that when the ” THD I ” incraese the ” THD U ' will increase also, but be carfull even if we have the same percentages of ” THD I ” in 2 different networks **it's not necessary** to have the same percantage of ” THD U ” for both, because it dependes on the value of the ” Harmonic Impedance ” of each network.

3 – In some time when the level of Voltage distortion is smaller than standard or definded value, we can accept, as THD I, till ” 40-45% “.

4 – For information, the ” IEC 61000,2 ” defined the percantage of Harmonic Voltage for each harmonic ” Odd & Even harmonics ” in LV networks, and also in some countries the Electricity Co. define the ” THD U ” for their :V & MV networks.

Regards.

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