This part of IEC 61557 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. 
NOTE Common worldwide three-phase distribution systems are depicted in IEC 61010-1.dition 3.0 2019-07 INTERNATIONAL STANDARD NORME INTERNATIONALE colour inside Electrical safety in low voltage distribution systems up to 1 000 V a.c. and 1 500 V d.c. – Equipment for testing, measuring or monitoring of protective measures – Part 7: Phase sequence Sécurité électrique dans les réseaux de distribution basse tension au plus égale à 1 000 V c.a. et 1 500 V c.c. – Dispositifs de contr？le, de mesure ou de surveillance de mesures de protection – Partie 7: Ordre de ph