This part of IEC61000 is concerned with conducted electromagnetic phenomena (disturbances and signals from mains communicating systems) in the frequency range from 0kHz to 150kHz. It gives compatibility levels for public low voltage a.c. distribution systems having a nominal voltage up to 420V, single-phase, or 690V, three-phase, and a nominal frequency of 50Hz or 60Hz.The compatibility levels specified in this document apply at the point of common coupling. At the power input terminals of equipment receiving its supply from the above systems the levels of the conducted electromagnetic disturbances can, for the most part, be taken to be the same as the levels at the point of common coupling. In some situations this is not so, particularly in the case of a long line dedicated to the supply of a particular installation, or in the case of an electromagnetic phenomenon generated or amplified within the installation of which the equipment forms a part.Compatibility levels are specified for conducted electromagnetic phenomena of the types which can be expected in public low voltage power supply systems, for guidance in the definition of:the limits to be set for conducted emissions into public power supply systems (including the planning levels defined in 3.1.5).the immunity limits to be set by product committees and others for the equipment exposed to the conducted electromagnetic phenomena present in public power supply systems.NOTE More information on compatibility levels and other main basic EMC concepts is given in IECTR61000‑1‑1.The electromagnetic phenomena considered are:voltage fluctuations and flicker;harmonics up to and including order 40;interharmonics up to the 40th harmonic;voltage distortion in differential mode at higher frequencies (above the 40th harmonic up to 150kHz);voltage dips and short supply interruptions;voltage unbalance;transient overvoltages;power frequency variation;d.c. components;signals from mains communicating systems (MCS).Most of these phenomena are described in IECTR61000‑2‑1. In cases where it is not yet possible to establish compatibility levels, some information is provided in AnnexB.