Aging of Electrical Appliances Due to Harnmonics of the Power System´s Voltage

Average values for the exponents of a weighted harmonic factor are derived for transformers, induction and universal machines as they occur in electrical appliances. The derivation is based on a theoretical loss analysis and on experimentally obtained temperature data [1,2]. The influence of the temperature on the lifetime of the above electromagnetic devices is discussed. An attempt has been made to recommend a limit for the value of the weighted harmonic factor which indirectly limits the sum of the weighted amplitudes of occurring voltage harmonics in a distribution system. Thus a criterion has been devised which judges harmonic voltage spectra based on the temperature increase they produce in an electromagnetic apparatus. As an example, two possible sets of voltage harmonic spectra are discussed that would protect consumers, as well as utility systems, from adverse effects. The work described has been supported by the U.S. Department of Energy.