IEC 60152:2021

IEC 60152:2021 specifies methods and rules for the designation of phase difference between two items in a three-phase AC system. The designations are intended to be applied in the technical documentation of industrial installations, equipment, and products, and also on markings of equipment and products.
IEC 60152:2021 cancels and replaces the first edition published in 1963. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) the title has been updated to reflect the content of the document;
b) the concept of identifying conductors with hour number has been removed as the concept is considered out of date and other means for identifying conductors exists;
c) definition of hour number (clock number) and phase difference introduced.