IEC TR 61000-3-6:1996

This technical report outlines principles which are intended to be
used as the basis for determining the requirements for connecting
large distorting loads (producing harmonics and/or interharmonics)
to public power systems. The primary objective is to provide
guidance for engineering practices which will ensure adequate
service quality for all connected consumers.

Since the guidelines outlined in this report are necessarily based
on certain simplifying assumptions, there is no guarantee that this
approach will always provide the optimum solution for all harmonic
problems. The recommended approach should be used with flexibility
and judgment as far as engineering is concerned, when applying the
given assessment procedures in full or in part.