One of the main harmonic effects on power cables is additional heating due to increased losses2R. This issue can be attributed to two famous phenomena of skin effect(skin effect) And the effect of proximity(proximity effect) Attributed, both of which vary as a function of frequency, size, and conductor distance. Also, cables involved in system resonance may be subjected to voltage and corona pressure, which can lead to dielectric failure. (Insulation) Be.
Losses I2R
These losses depend on two electrical parameters of cable current and its resistance.
RMS flow
Losses I2R is variable relative to the square of the RMS current, so harmonics should be minimized as this leads to higher conductor losses, which in turn leads to an increase in temperature and, in the worst case, a significant reduction in conductor life..
It should be noted that non-sinusoidal components can significantly increase the net RMS flow, because their squares are added directly to the squares of the basic components..
Effective cable resistance:
As mentioned, the resistance of the cables is due to the skin effect(skin effect) And the effect of proximity (proximity effect) May increase. Skin effect is when unequal flux bonds at the cross-section of the cable cause AC current to flow through the outer edge of the conductor.. On the other hand, conductors placed close to each other and carrying alternating current change the current distribution in each conductor by mutual reaction.. This leads to an increase in the effective resistance in the cable, or the proximity effect. In this case, if the conductor distance is more than 10 equal to the conductor diameter, the proximity effect will be less than 1% and can be ignored.
Both of these phenomena are proportional to the frequency of AC current, and when this current increases, they increase and can become effective AC resistance. (R) increase more than the DC resistance. Consequently, when a current waveform rich in high-frequency harmonics flows through the cable, the resistance of the cable increases proportionally and even more, resulting in the factor I2R becomes larger. And this is another harmonic effect on power cables.
The effect of harmonic heating in cables is usually not much considered. However, in the design and measurement, it should be considered so as not to cause such unwanted effects.
