UNE-EN IEC 60051-3:2021

Part 3 of the standard applies to direct acting indicating wattmeters and varmeters having an analoguedisplay.NOTE For multifunction instruments, see Part 7.It also applies to:" Non-interchangeable accessories (as defined in Subclause 3.1.23 of IEC 60051-1:2016) used withwattmeters and varmeters." Combination of the instruments and the accessories provided that the adjustments have been madefor the combination;" Direct acting indicating electrical measuring instrument whose scale marks do not corresponddirectly to its electrical input quantity, provided that the relationship between them is known;" Instruments and accessories having electronic devices in their measuring and/or auxiliary circuits.This standard 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 asaccessories.