IEC 60051-3:2018 applies to direct acting indicating wattmeters and varmeters having an analogue display.
IEC 60051-3:2018 also applies to:
•    non-interchangeable accessories (as defined in 3.1.23 of IEC 60051-1:2016) used with wattmeters and varmeters,
•    a combination of the instruments and the accessories provided that the adjustments have been made for the combination,
•    direct acting indicating electrical measuring instruments whose scale marks do not correspond directly to their electrical input quantity, provided that the relationship between them is known,
•    instruments and accessories having electronic devices in their measuring and/or auxiliary circuits.
IEC 60051-3:2018 does not apply to:
•    special purpose instruments which are covered by their own IEC standards,
•    special purpose devices which are covered by their own IEC standards when they are used as accessories.
IEC 60051-3:2018 cancels and replaces the fourth edition published in 1984 and Amendment 1:1994. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a)    updating of content in line with new editions of IEC 60051-1 and IEC 60051-9,
b)    addition of Annex A to specify the nonconformity classification of test items.
IEC 60051-3:2018 is to be used in conjunction with IEC 60051-1:2016.