This is due to “Skin Effect” which is the tendency for higher frequency currents to flow near the surface of the conductor. Since non-linear loads produce harmonic currents with frequencies considerably higher than the power system fundamental frequency, these currents encounter much higher impedances as they propagate through the power system than does the fundamental frequency current. What other effects besides distorting the shape of the voltage and current sinusoids, do harmonics cause? Any SMPS equipment will create continuous distortion of the power source that stresses the facility’s electrical distribution system and power equipment. This illustration is similar to an electrical distribution system with non-linear loads generating harmonics. You would effectively be hit with alternating cold and hot water! Therefore, the performance and function of the shower is reduced by other systems. The end result is you get burned! Now imagine that someone at a sink alternately turns on and off the cold and hot water. Have you ever taken a shower when someone turns on the cold water at the sink? You experience the effect of a pressure drop to the cold water, reducing the flow of cold water. The distortion travels back into the power source and can affect other equipment connected to the same source.Įxample: To give an understanding of this, consider a water piping system. This is referred to as a harmonic distortion and is measured in Total Harmonic Distortion (THD). These current pulses create significant distortion in the electrical current and voltage wave shape. These non-linear power supplies draw current in high amplitude short pulses. In today’s environment, all computer systems use SMPS that convert utility AC voltage to regulated low voltage DC for internal electronics. ![]() What does harmonic distortion do to the power at my facility? Single-phase non-linear loads are prevalent in modern office buildings while three-phase non-linear loads are widespread in factories and industrial plants. There are two basic types of non-linear loads: single-phase and three-phase. SMPS equipment typically forms a large portion of the electrical non-linear load in most electrical distribution systems. ![]() These types of non-linear loads or SMPS equipment generate the very harmonics they are sensitive to and that originate right within your building or facility. The above-mentioned electronic SMPS equipment is also referred to as non-linear loads. Harmonics are caused by and are the by-product of modern electronic equipment such as personal or notebook computers, laser printers, fax machines, telephone systems, stereos, radios, TVs, adjustable speed drives and variable frequency drives, battery chargers, Uninterruptable Power Supplies, and any other equipment powered by switched-mode power supply (SMPS) equipment. When this happens, the power panel or transformer vibrates and emits a buzzing sound for the different harmonic frequencies. When harmonic frequencies are prevalent, electrical power panels and transformers become mechanically resonant to the magnetic fields generated by higher frequency harmonics. ![]() ![]() In modern test equipment today, harmonics can be measured up to the 63rd harmonic. For example, if the fundamental power frequency is 60 Hz, then the 2nd harmonic is 120 Hz the 3rd is 180 Hz, etc. Harmonics are currents or voltages with frequencies that are integer multiples of the fundamental power frequency being 50 or 60Hz (50Hz for European power and 60Hz for American power). To help understand the impact and significant role harmonic distortion can play, a bit of information concerning THD is warranted. These issues can have harmful and/or costly effects on the overall health and functionality of your electrical distrbution system and it’s connected equipment. It is important to note that THD (Total Harmonic Distortion) levels above 5% can shorten the life of the electrical equipment and contribute to other issues with electronics such as unexplained glitches on computers and test & monitoring equipment and/or systems. General Information – Harmonic Distortion By s3energy Energy, Learn, Power Quality 0 comments Harmonic Distortion General Information
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