scope:

PREFACE

This publication has been prepared by IEC Technical Committee No 25, Quantities and Units, sand their Letter Symbols.

When Publication 27-1 was originally prepared, electro technology concerned itself primarily with sinusoidal waveforms Accordingly, Clause 4 that publication gave special notations suitable for sinusoidal waves, but did not cover more complicated situations.

In modern technology, there is need to distinguish between "peak" and "maximum" to indicated values of running averages of various types This publication was therefore developed by TC 25, not with the intention of changing Publication 27-1 but for purpose of extending its usefulness to the problems of modern practice which involve non-sinusoidal waveforms, noise and other complications The present publication is therefore a supplement to Publication 27-1