Increase hysterisis and eddy current losses in the electromagnetic apparatus such as transformers, ballasts. Input transformers (also called isolation transformers) in electronic modules are also affected by the harmonics the same way.
The overheating of iron core due to increased losses above could lead to fusing of laminations or damage of the iron core otherwise. This is more serious consequence of harmonics in the system than the power loss itself.
Here is an extract from "IEEE recommended practices and Requirements for Harmonic control in Electrical power Systems" IEEE Std 519-1992.
The non-linear loads connected to electric power systems include static power converters, arc discharging devices, saturated magnetic devices, mills and rotating machines. Most of the modern industries are equipped with static power converters. These devices are capable of supplying power without any interruption and also easy to convert from ac-dc, dc-ac, etc. These non-linear loads change the sinusoidal nature of the ac power current (and consequently the voltage drop), thereby resulting in the flow of harmonic currents in the ac power system that can cause interference with communication circuits and the other types of equipment. When reactive power compensation, in the form of power factor improvement capacitors, is used with these non-linear loads, resonant conditions can occur that may result in high levels of harmonic voltage and current distortion. The main effects of voltage and current harmonics within the power system are:
„h Amplification of harmonic levels resulting from series and parallel resonance,
„h Reduction of efficiency in power generation, transmission and utilization,
„h Aging of the insulation of electrical plant components and thus shortening of their useful life,
„h Plant mal-operation.
Hope this will make a brief introduction about Harmonics.
Pls do not hesistate to ask in perticular...
-nag400
