IEC 61557-7:2019 RLV contains both the official IEC International Standard and its Redline version. The Redline version is not an official document, it is available in English only and provides you with a quick and easy way to compare all the changes between the official IEC Standard and its previous edition.

IEC 61557-7:2019 specifies the requirements applicable to measuring equipment for testing the phase sequence in three-phase distribution systems. Indication of the phase sequence can be mechanical, visual and/or audible. This document does not apply to additional measurements for other quantities. It does not apply to monitoring relays. IEC 61557-7:2019 cancels and replaces the second edition published in 2007. This edition constitutes a technical revision. This edition includes the following changes with respect to the previous edition:
a) alignment of the structure with that of the whole IEC 61557 series;
b) updated requirements in 4.3 in accordance with new editions of IEC 61010-1 and IEC 61010-031;
c) the information on markings was extended;
d) the information on the operating instructions was extended;
e) complement to the information on the testing of leads;
f) test leads for insulated conductors were introduced;
g) Annex B was added with information on phase sequence tests and indications.