IEC 60051-3-2018 pdf download.Direct acting indicating analogue electrical measuring instruments and their accessories – Part 3: Special requirements for wattmeters and varmeters.
This part of IEC 60051 applies to direct acting indicating wattmeters and varmeters having an analogue display.
NOTE For multi-function instruments, see IEC 60051 -7.
It also applies to:
• non-interchangeable accessories (as defined in 3.1 .23 of IEC 60051 -1 :201 6) 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.
This document 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.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
IEC 60051 -1 :201 6, Direct acting indicating analogue electrical measuring instruments and their accessories – Part 1: Definitions and general requirements common to all parts
IEC 60051 -9, Direct acting indicating analogue electrical measuring instruments and their accessories – Part 9: Recommended test methods
3 Terms and definitions
See IEC 60051 -1 :201 6.
4 Description, classification and compliance
4.1 Description
See IEC 60051 -1 :201 6.
4.2 Classification
See IEC 60051 -1 :201 6.
4.3 Compliance with the requirements of this standard
See IEC 60051 -1 :201 6.
5 Requirements
5.1 Reference conditions
See IEC 60051 -1 :201 6; the reference value of the influence quantities should be as given in Table 2 of IEC 60051 -1 :201 6 and Table 1 .
5.2 Limits of intrinsic uncertainty, fiducial value
5.2.1 Limits of intrinsic uncertainty
See IEC 60051 -1 :201 6.
5.2.2 Correspondence between intrinsic uncertainty and accuracy class
See IEC 60051 -1 :201 6.
5.2.3 Fiducial value
5.2.3.1 The fiducial value for a wattmeter or varmeter corresponds to the following.
5.2.3.2 The upper limit of the measuring range for the following:
• instruments with the mechanical and/or electrical zero at one end of the scale;
• instruments with the mechanical zero outside the scale irrespective of the position of the electrical zero;
• instruments with the electrical zero outside the scale irrespective of the position of the mechan-ical zero.
The class index for these wattmeters or varmeters is marked using Symbol E-1 given in Table 6 of IEC 60051 -1 :201 6 (see Clause 6 of IEC 60051 -1 :201 6).
5.2.3.3 The sum of the absolute values of the upper and lower limit of the measuring range when both the mechanical and the electrical zeros are displaced within the scale.
The class index for these wattmeters or varmeters is marked using Symbol E-1 given in Table 6 of IEC 60051 -1 :201 6 (see Clause 6 of IEC 60051 -1 :201 6).
5.2.3.4 The span for an instrument whose scale marks do not correspond directly to its electrical input quantity.
The class index for these wattmeters or varmeters is marked using Symbol E-1 0 given in Table 6 of IEC 60051 -1 :201 6 (see Clause 6 of IEC 60051 -1 :201 6).
This does not apply to a wattmeter or varmeter designed to be used in conjunction with one or more shunt(s), series resistor(s) (impedance(s)) or (an) instrument transformer(s). These instruments are treated in accordance with 5.2.3.2 or 5.2.3.3 as appropriate.
5.3 Nominal range of use and variations
5.3.1 Nominal range of use
See IEC 60051 -1 :201 6; the limits of the nominal range of use for influence quantities shall be as given in Table 3 of IEC 60051 -1 :201 6 and Table 2.IEC 60051-3 pdf download.