Electrical Harmonics For Dummies

Current harmonics are caused by non linear loads.

Electrical harmonics for dummies. Power system harmonics are not a new phenomenon. In fact a text published by steinmetz in 1916 devotes considerable attention to the study of harmonics in three phase power systems. And metering circuits providing erroneous readings all of which is caused by the harmonic content of the electrical system of your facility even if you don t actually generate the harmonics that are effecting your equipment. Harmonics in the electrical power distribution system combine with the fundamental frequency 50hz or 60hz supply to create distortion of the voltage and or current waveforms.

Low thd is such an important feature in power systems that international standards such as iec 61000 3 2 set limits on the harmonic currents of various classes of power equipment. On a 60 hz system this could include 2nd order harmonics 120 hz 3rd order harmonics 180 hz 4th order harmonics 240 hz and so on. Arillaga et al power system harmonics isbn 0 471 90640 9 3. For an electrical system to function properly any harmonic resonance present and or harmonic distortion must be eliminated when there is a large supply of individual currents from a number of harmonic current sources the system could resonate.

In a normal alternating current power system the current varies sinusoidally at a specific frequency usually 50 or 60 hertz when a linear electrical load is connected to the system it draws a sinusoidal current at the same frequency as the voltage though usually not in phase with the voltage. Power factor can be seen as a complex problem to comprehend and to understand or you can simplify it to the basics. In this document i will aim to make it as real and simple so that everyone can. Electrical power system harmonics design guide 2.

Harmonic distortion for dummies. Harmonics are electric voltages and currents on an electric power system that can cause power quality problems. Introductions to ac circuit analysis typically focus on power factor as being determined by the phase relationship between the voltage and current in a circuit while generally ignoring the effect of thd on power factor. P519a task force harmonics working group ieee pes t d committee and scc22 power quality guide for applying harmonic limits on power systems un approved draft 4.

In steinmetz s day the main concern was third harmonic currents caused by saturated iron in transformers and machines.