Another part flows upstream through the transformer towards the grid. One part of the generated harmonic currents circulate to all connected equipment within its electrical power system, causing harmonic stress that gets wasted as heat loss, equipment failure and unwanted tripping. Summarily, total current harmonic distortion (THDi) is a measure of these current harmonics.Ģ. Non-Linear loads like DC drives, VFD Drives etc., generate harmonic currents in integer multiples of fundamental frequency (I2=2x50Hz, I3=3x50Hz, and so on). How much harmonic distortion is acceptable? When harmonic distortion causes power problems and equipment failure?ġ. What are the types of harmonic distortions? While THDi (current) and THDv (voltage) are the two types, Total Demand Distortion (TDD) calculates the extent and measure of THDi. What causes harmonic distortion? It's Non-linear load and impedance of the power system. On the other hand, the high-frequency harmonics, in the integer multiple (2x50Hz, 3x50Hz, and so no) of fundamental-frequency (50Hz), do no real work and get wasted by causing heat loss in plant equipment. The fundamental-frequency power (50Hz) is the active power that does all the real work and drives plants and machinery. THDi is a ratio of square root sum of all high-frequency harmonic current-squares (I2, I3, I4, and so on) to fundamental frequency (I1) current. While defining Total harmonic distortion (THDi, current), it merely represents a unit of harmonic distortion and not the extent or measure of harmonic distortions. Total harmonic distortion (THDv, voltage) and distortion factor are related terms defined by a ratio of square root sum of all high-frequency harmonic voltage-squares (v2, v3, v4, and so on) to fundamental frequency (v1) voltage.
Total harmonic distortion full#
When a plant with high NLL runs at full load, it crams harmonics and active power in the power system, causing unacceptable energy surge wherein harmonic distortion is the ratio of harmonics to fundamental frequency (f1 -50Hz) component.