We know that it is divided into EMC testing EMI and EMS testing requirements. Ability to assess the primary analyte EMI interference environment (this ability to be smaller the better), and the EMS is the ability to resist environmental interference analyte evaluation (this ability to be as strong as possible). But whether or EMS EMI testing, which in fact is largely measured on the "harmonic", and that what is "harmonic" of? Terry Jun (SKYLABS) give you to talk about it today.
Before the introduction of harmonics, Terry first to detect and introduce you to the great Fourier and controversy he caused.
In 1807, 39-year-old French mathematician Fourier shown on French scientific society a paper (the paper was published only after the birth of 21 years), the paper has a highly controversial judgment in that era: "Any periodic signal may be a continuous combination of "an appropriate set of sine curve. The paper caused great concern two other famous French mathematician Laplace and Lagrange.
58-year-old was in favor of Laplace Fourier views. 71-year-old Lagrange (mathematicians and physicists) are clearly opposed on the grounds that the opposition "can not be combined into a sinusoidal signal with edges and corners." At that time succumbed to the prestige Lengrand day, this was a young mathematician papers until 15 years after the death of Lengrand day was not published. After scientists proved: Fourier was right!
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a limited number of sinusoidal really can not be combined into one signal with angular, However, the combination of an infinite number of sinusoidal terms of energy, with the signal can be very approximate angular infinite.
Fourier transformation formula is more complicated here Tianzong monarch will not start to explain, but as long as you remember that this formula is our communications and electronics played a role in the foundation stone. Modern electronic and communication field, it is through the Fourier transform shows the relationship between the relationship between frequency domain and time domain, the fundamental and harmonics.
Measuring the electrical parameters in the analysis, such that the Fourier transform of any periodic signal can be decomposed into a set of sine wave DC component and a different amplitude, frequency, phase. These frequency sine wave meets a rule: an integer multiple of a frequency. This frequency is called the fundamental frequency, whereas other frequencies called harmonic frequencies. If the harmonic frequency is N times the fundamental frequency, called harmonics N. In fact, harmonic analysis Fourier transform nature.
Harmonics power production, transport and utilization efficiency is lowered, so that overheating of the electrical equipment, vibration and noise, and insulation aging, shorten the life, or even malfunction or burning. Harmonics can cause local series resonance or parallel resonance power system, harmonic content enlarge, causing capacitor equipment destroyed. Harmonics can also cause automatic device malfunction protection and the energy metering confusion. For the external power system, the harmonics of the communication device and the electronic device will produce severe interference. Back to our measurement of EMC, which is actually a great piece of harmonic measurement, also called EMC rectification "harmonic" suppression based.
We tested stray RF test (RSE and the CSE), the EMC test conducted and radiated emissions (EMI), voltage fluctuations and flicker in the EMS test measurement requirements are actually on the "harmonics" of.
The figure is a vertical harmonic scintillation day testing laboratory analysis systems. It is equipped with a programmable power inlet with fast transient response, excellent stability, high peak current capability, programmable test, voltage output range 0-300VAC vary for dozens of different voltage waveforms that supports the lower current 16A single-phase, three-phase civil and industrial equipment and other electromagnetic compatibility test requirements, and its ability to meet the harmonic analysis of the current value of the order of 1-40. And in accordance with IEC / EN 61000-3-2 standards and GB 17625.2, voltage fluctuations and flicker measurement of the voltage change access device with rated current ≤16 A produced in public low-voltage supply system.