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In an electric power system, a harmonic of a voltage or current waveform is a sinusoidal wave whose frequency is an integer multiple of the fundamental frequency. Harmonic frequencies are produced by the action of non-linear loads such as rectifiers, discharge lighting, or saturated electric machines.
Transformers and rectifiers in power systems produced harmonic currents that inductively coupled into adjacent open-wire telephone circuits and produced audible telephone interference.
Harmonics are currents or voltages with frequencies that are integer multiples of the fundamental power frequency, which in the U.S. is 60 Hertz. If the first fundamental frequency is 60 Hz, then the second is 120 Hz, and the third is 180 Hz. Here are a few examples of issues that might be related to harmonics.
The actual power system, however, contains voltage or current components, called harmonics, whose frequencies are integral multiples of the power system frequency. The second harmonic for a 60 Hz system is 120 Hz, the third harmonic is 180 Hz, etc. Typically, only odd harmonics are present in the power system.
What are Harmonics? Alternators produce alternated voltages ( V) and currents ( I) with a sinusoidal wave form and a frequency ( f) of 50 Hz or 60 Hz (this frequency, the first harmonic, is usually designated by industrial frequency or fundamental ), what can be observed in Figure 1. Figure 1 – Sinusoidal alternated voltage.
Harmonics are produced by nonlinear loads or devices that draw non-sinusoidal currents. An example of a nonlinear load is a diode, which permits only one-half of the otherwise sinusoidal current to flow. Another example is a saturated transformer, whose magnetizing current is no sinusoidal.
May 4, 2023 · In an electrical power system, harmonics can be defined as the multiple of the current or voltage at the fundamental voltage frequency. Anytime you observe a waveform, and it deviates from the expected sinewave shape, it contains harmonics.
