This part of IEC 60051 applies to direct acting indicating phase meters, power factor meters
and synchroscopes having an analogue display.
This document also applies to non-interchangeable accessories (as defined in 3.1.23 of
IEC 60051-1:2016) used with phase meters, power factor meters and synchroscopes.
This document also applies to a phase meter or power factor meter whose scale marks do not
correspond directly to its electrical input quantity, provided that the relationship between them
is known.