This part of IEC 62271 is applicable to phase comparators designed to be plugged into the testing points of a voltage detecting and indicating system (VDIS) according to IEC 62271-213, to give an indication of the result of a phase comparison.

The main usage is to provide clear evidence of the phase relationship between two energized parts of a high-voltage network, at the same nominal voltage and frequency before coupling them.

This document or parts of the document can also be applied to the phase comparison function of other devices connected to the VDIS upon agreement between manufacturer and user.

This document does not cover phase comparators to be used directly on bare parts of live electrical installation at the nominal voltage of the networks. These phase comparators are covered by IEC 61481-1 and IEC 61481-2.