![what is a harmonic what is a harmonic](http://www.sengpielaudio.com/ClarinetHarmonics.gif)
The presence of harmonics will also mean that although you will get billed for the power that you are supplied, a large percentage of that power may be unusable. In the long term, this degrades an electrical system. Harmonics cause things to run hot, which cause stress on the cables and equipment. It is possible that the investment that you made in your motors & drives will not be realised if they are damaged and need replacing before their expected life span. For example, the presence of harmonics reduces the life of equipment. Harmonics are very harmful within an electrical system and can have serious consequences. What are the effects of harmonics in your electrical system? If you are replacing your motor's bearings & insulation often, that's a strong indication of the presence of harmonics. Other signs are cables running hot, hot switchboards or overheating motors. If you occasionally experience some unexplained occurrences such as flickering lights, alarms going off, or MCB's, MCCB's, RCD's and Earth Leakage devices tripping for no apparent reason, you are most likely experiencing harmonics in your electrical environment. How do you know if you have harmonics in your electrical system? The presence of harmonics in an electrical system distorts the clean shape of a sine wave. 150Hz is called the 'third' harmonic (3 x 50Hz), 250Hz is called the 'fifth' harmonic (5 x 50Hz), etc. The frequencies of the harmonics are 100Hz, 150Hz, 200Hz, 250Hz, 300Hz, 350Hz and so on. In the case of the Australian electricity supply, the fundamental frequency is 50Hz. Harmonic frequencies are equally spaced by the width of the fundamentalfrequency and can be found by repeatedly adding that frequency. A harmonic of a wave is a component frequency of the signal that is an integer multiple of the fundamental frequency.įor example, if the fundamental frequency is f, the harmonics have frequencies 2f, 3f, 4f. In simple terms, harmonics are extra frequencies that when present in an electrical circuit, distort the AC sine wave.