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This effect can require special consideration in the design of an electric system to serve non-linear loads. [10] In addition to the increased line current, different pieces of electrical equipment can suffer effects from harmonics on the power system.
Harmonic oscillators occurring in a number of areas of engineering are equivalent in the sense that their mathematical models are identical (see universal oscillator equation above). Below is a table showing analogous quantities in four harmonic oscillator systems in mechanics and electronics.
To understand a system with an input and an output, such as an audio amplifier, we start with an ideal system where the transfer function is linear and time-invariant.When a sinusoidal signal of frequency ω passes through a non-ideal, non-linear device, additional content is added at multiples nω (harmonics) of the original frequency.
The possible effects if the level of harmonics, known as total harmonic distortion becomes too high include damage to sensitive electronic equipment [5] and reduction in the efficiency of the HV transformer. [6] The efficiency of electrical loads can be improved by attenuating harmonics at the supply, or by preventing their generation.
Nonlinearities that give rise to amplitude distortion in audio systems are most often measured in terms of the harmonics (overtones) added to a pure sinewave fed to the system. Harmonic distortion may be expressed in terms of the relative strength of individual components, in decibels, or the root mean square of all harmonic components: Total ...
This is no passing metaphor; a weight on a spring is described by exactly the same second order differential equation as an RLC circuit and for all the properties of the one system there will be found an analogous property of the other. The mechanical property answering to the resistor in the circuit is friction in the spring–weight system.
Mains hum, electric hum, cycle hum, or power line hum is a sound associated with alternating current which is twice the frequency of the mains electricity. The fundamental frequency of this sound is usually double that of fundamental 50/60 Hz , i.e., 100/120 Hz, depending on the local power-line frequency .
Harmonics (electrical power) – Sinusoidal wave whose frequency is an integer multiple; Harmonic generation – Nonlinear optical process; Harmonic oscillator – Physical system that responds to a restoring force inversely proportional to displacement; Harmony – Aspect of music; Pure tone – Sound with a sinusoidal waveform