Why these harmonics always present?

1. Why do harmonics appear?
2. Why only odd harmonics are present?
3. What is the main cause of harmonic distortion?
4. What causes 5th and 7th harmonics?

Why do harmonics appear?

Harmonics are the result of nonlinear loads that convert AC line voltage to DC. Harmonics flow into the electrical system because of nonlinear electronic switching devices, such as variable frequency drives (VFDs), computer power supplies and energy-efficient lighting.

Why only odd harmonics are present?

Most electrical loads (except half-wave rectifiers) produce symmetrical current waveforms, which means that the positive half of the waveform looks like a mirror image of the negative half. This results in only odd harmonic values being present.

What is the main cause of harmonic distortion?

Harmonic distortions are usually caused by the use of nonlinear loads by the end users of electricity. Nonlinear loads, a vast majority of which are loads with power electronic devices, draw current in a nonsinusoidal manner.

What causes 5th and 7th harmonics?

Magnetic cores, such as transformer and rotating machines that require third harmonic current to excite the iron. Synchronous machines (winding pitch produces fifth and seventh harmonics)