Characterisation of Harmonic Distortions Produced by Small Domestic Back-Up Generators

Electric generators are manufactured or expected to be manufactured with the minimum allowable limits of harmonics as stipulated by the IEEE 519-1992 and other international standards. Practical performances of these generators showed that they do produce harmonic distortions in quantities that are inimical to other appliances supplied and proper operation expected of them during their operational lives. This paper performed a detailed assessment of over eighty (80) generators harmonic contents at different loading conditions to determine the magnitude and orders of harmonics produced. The investigation was conducted with field test at different locations in Ibadan, Nigeria. Measurement data for various generators supplies at different load conditions were recorded using digital storage oscilloscope. The measurement data showed and established the levels and extent of harmonics produced by the 950V A and 2000V A electric generators. The experimental results obtained from this research work provide experimental evidence that 950V A generators produce harmonics distortion of 2^nd, 3^rd, 4th, 5^th, 6^th, 7^th, 8^th and 9^th orders in an averaged voltage total harmonic distortion of 106% on noload and 118% on 60% load conditions. The 2000VA generators generate harmonics distortion of orders 3^rd, 5^th, 7^th and 9^th with an averaged voltage total harmonic distortion of 92 % on no-load and 97% on 60 % load conditions as against IEEE minimum limit of 5 %.