Single Phase Harmonic Limits

The International Electrotechnical Commission (IEC) sets limits for harmonics in the current of small single-phase or three-phase loads, less than 16 A per phase, in Electromagnetic compatibility (EMC) - Part 3-2: Limits - Limits for harmonic current emissions (IEC 61000-3-2). The IEEE Single Phase Harmonics Task Force (P1495) is developing a similar standard for single phase loads of less than 40 A. There is, however, still no agreement on what such limits should be, or whether limits are even needed. Electric utilities are concerned about the effects of harmonics on their systems: telephone noise, excessive heating of transformers and other equipment, capacitor damage, and others, and would like to limit the levels of harmonics produced by loads on their systems. Manufacturers, however, are concerned about the cost of changes to their equipment to reduce harmonic production. This paper summarizes the IEC limits and the proposed IEEE limits, discusses the need for single phase harmonic limits, and presents what those limits might be