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Non-Linear AC Loads

December 16th Fact-of-the-Day

RF interference conducted-by and radiated-from AC power lines plagues most everyone interested in listening to weak LF, MF, or HF signals unless they use battery or solar powered receivers located far from the nearest power line. Nearly all that RF interference is due to the use of non-linear AC power loads. Power plant generators produce near-perfect sine waves at 50 or 60 Hz. Perfect low-frequency sine waves have no radio-frequency energy and cause no radio interference. Loads that are purely resistive, or that are simple combinations of pure resistance, inductance or capacitance, are linear and generate no RF energy. The RF noise generators in power distribution systems are the non-linear loads. Non-linear loads are loads that change as the voltage varies. Examples are gas-discharge lamps, rectifiers that start conducting after a certain voltage is reached, arc welders, and generally anything else that arcs. ©2004 Martek International All rights reserved.


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