Applies to transducers with electrical inputs and outputs for making measurements of a.c. electrical quantities with a nominal frequency between 5 Hz and 1 500 Hz. The output signal may be in the form of an analogue direct current or in digital form. Supersedes IEC 688-1 and IEC 688-2. This consolidated version consists of the second edition (1992) and its amendment 1 (1997). Therefore, no need to order amendment in addition to this publication.