What are harmonics?
Harmonics are in the same “family” as intermodulation. It’s new radio signals that are created by a non-linear device that are a multiple of a radio signal. Unlike intermodulation which requires two or more “parent” or fundamental signals to be created, harmonics are the product of just one signal. A 10 megahertz signal would have a second harmonic of 20 Mhz, a third harmonic of 30 Mhz, a fourth harmonic of 40 Mhz, and so on. Harmonics created in equipment are generally undesirable and can interfere with other communications services if not filtered out. Harmonics can also mix with other signals to form intermodulation. Harmonics can be created from fundamental BPL signals on powerlines. These have been observed in the field at typically 30 dB lower than primary BPL signals.
A. Harmonics are multiples of the fundamental frequency distortions found in electrical power, subjected to continuous disturbances. In a 60 Hz electrical system 350 Hz is the 5th harmonic, 420 Hz is the 7th harmonic, and so on. Harmonics are created by the use of non-linear devices such as UPS systems, solid state variable speed motor drives, rectifiers, welders, arc furnaces, fluorescent ballasts and personal computers. Individual harmonic frequencies will vary in amplitude and phase angle, depending on the harmonic source.
By definition, “Harmonics” is any integer multiple of a fundamental frequency. Most electronic equipment generates harmonics. We treat harmonics by using harmonic filters that reduce the harmonic current drawn by these loads and in effect reducing the distribution losses. These reduced distribution losses are our savings. We use passive harmonic filters and active harmonic filters as well. Harmonics is related to periodic waveforms. The power you get from the utility is alternating current whose frequency is 60 Hz. – therefore it is a periodic function of time. If we apply this definition, harmonic currents would be any multiple of 60 Hz – for instance, the 2nd harmonic is 120 Hz. the 3rd harmonic is 180 Hz, 4th Harmonic is 240 Hz, and so forth. There are certain loads that due to their operating characteristics draw current with higher frequency than the 60 Hz. supplied by the Utility Company. One example of such a load is the Personal Computer. Other examples include Variable Speed D
