This International Standard applies only to newly manufactured static watt-hour meters of accuracy classes 0.2 S and 0.5 S, for the measurement of alternating-current electrical active energy of a frequency in the range 45 Hz to 65 Hz and to their type tests only. It applies only to transformer-operated static meters for indoor application consisting of one or more measuring elements and registers enclosed together in the same case.

NOTE:
IEC 185 describes transformers having a measuring range of 0.05 In to 1.2 In, or of 0.05 In to 1.5 In, or of 0.05 In to 2 In and transformers having a measuring range of 0.01 In to 1.2 In for accuracy classes 0.2 S and 0.5 S. As the measuring ranges of a meter and its associated transformers have to be matched and as only transformers of classes 0.2 S and 0.5 S have the accuracy required to operate the meters of this standard, the measuring range of the meter will be 0.01 In to 1.2 In.

It also applies to operation indicators, test outputs and meters which measure energy in both directions.

This standard does not apply to:
a) watt-hour meters where the voltage across the connection terminals exceeds 600 V (line-to-line voltage for meters for polyphase systems);
b) portable meters and meters for outdoor use;
c) data interfaces to the register of the meter;
d) reference meters.

Where the display and/or the memory(ies) is/are external or where other elements are enclosed in the meter case (such as maximum demand indicators, telemetering, time switches or remote control, etc.) this standard applies only to the metering section. This standard does not cover the acceptance tests and the conformity tests (both testing procedures are connected with legal requirements of the different countries and could only be taken care of partially). For rack-mounted meters, the mechanical properties are not covered in this standard.

Specifies requirements for electronic watthour meters of accuracy classes 0.2 S and 0.5 S suitable for installation indoors. This Standard is technically identical with and reproduced from IEC 687:1992.

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