what is Harmonic
Harmonics, voltage and electrical current that the power grid caused by some sort of electrical charges.
The cause harmonic
Technological advances in the manufacture of semiconductor devices (such as diodes, thyristors or SCR, IGBT, GTO, etc.) has caused the automatic process instead of the contactors and relays controllers used semiconductor. The pieces on permanent power supplies used in hospitals, banks, malls, etc. abound Shvnd.vyzhgy protection of the parts deform and flow into a wave form that is not sinusoidal but periodic are. In the normal AC power systems, sinusoidal voltage at a particular frequency, usually 50 or 60 Hz line when a charge is connected to the system, in this case the same frequency sinusoidal voltage with a nonlinear load such as Mygyrd.vqty Rectification is connected to the power system creates a process that is not exactly sinusoidal.
In the following two examples can be seen streaming out. First and second current flow without distortion is a distortion. As can be seen in the case of equal power consumption on both occasions, at times distorted significantly more effective flow of time, smooth and without distortion. This means overload and be more casualties.
Mathematics (Fourier series) has proven that the current wave of a series of sine waves with wave and multiples of the fundamental frequency it is formed. Home to the original wave and other wave frequency waves according to their frequency, called harmonics. For example, the third harmonic, fifth, seventh, etc. In other words, a network of 50 Hz, the third harmonic frequency of the fifth harmonic frequencies 150 and 250 Hz.
Distorted waveforms, harmonics alone does not provide information about. What helps the designer on harmonic analysis harmonic spectrum graph is. Measuring devices capable of measuring the harmonics are normal. True RMS system harmonic measurements performed by the devices. Also measure the frequency spectrum by experts and using the devices Pavranalayzr done.
Total Harmonic Disturtion (THD)
Total harmonic distortion, or THD is a common measurement of the level of harmonic distortion present in power systems. THD is defined as the ratio of total harmonics to the value at fundamental frequency.
where Vn is the RMS voltage of nth harmonic and n = 1 is the fundamental frequency
The most common non-linear loads, which are harmonic generators include: 1-UPS2. AC motor speed controller 3. DC motor controller 4-frequency 5-dimmer lighting 6-inverter 7. Battery 8-arc furnace 9-arc welding devices 10. Electronic Ballast 11. The induction furnace 12. The switching power supply
Problems caused by harmonics
Depending on the type, number and amount of harmonics generated by the load, the general problems in the network include: 1-warming too conductors2. Strong or weak light fluorescent lamps 3. A capacitor failure 4-warming and excessive downtime transformers and motors. 5-flickering gas lamps 6-acting automatic fuses 7-burning fuse without apparent reason 8-interference in telecommunications 9-interference phone lines 10-failure measurement devices 11-warming too keys. 12-locking Computers Today, most electric industry concerned, and its consequences are dealing with harmonics.