IEC 60051-3 pdf free download

IEC 60051-3 pdf free download.Direct acting indicating analogue electrical measuring instruments and their accessories一 Part 3: Special requirements for wattmeters and varmeters.
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 60051-1:2016 (see Clause 6 of IEC 60051-1:2016).
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 60051-1:2016 (see Clause 6 of IEC 60051-1:2016).
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-10 given in Table 6 of IEC 60051-1:2016 (see Clause 6 of IEC 60051-1:2016).
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 60051-1:2016; the limits of the nominal range of use for influence quantities shall be as given in Table 3 of IEC 60051-1:2016 and Table 2.
5.3.2 Limits of variations See lEG 60051-1:2016.
5.3.3 Conditions for the determination of variations See IEC 60051-1:2016.
5.3.4 DetermInation of variation due to power factor
The power factor shall be lagging for instruments of class indices 0,5 and greater. For instruments of class indices 0,3 and smaller, the test shall be carried out using both lagging and leading power factors. The test shall be carried out with PF = 0.
For the recommended test, see IEC 6005 1-9.
5.3.5 Special tests for variations
Special tests using combinations of the components of the measured quantity may be carried out when considered necessary by agreement between manufacturer and user.
5.4 Operating uncertainty, overall system uncertainty and variations
See IEC 60051-1:2016.
5.5 Electrical requirements
5.5.1 ElectrIcal safety requirements
See IEC 60051-1:2016.
5.5.2 Self-heating See IEC 60051-1:2016.
5.5.3 PermIssible overloads
5.5.3.1 Continuous overload
For the recommended test, see IEC 6005 1-9.
Wattmeters and varmeters, together with their non-interchangeable accessory (if any), except for instruments fitted with a non-locking switch, shall be subjected to a continuous overload of 120 % of the rated values of current and voltage sequentially, the other value being maintained at its rated value. The duration of each application shall be 2 h.
After having cooled to the reference temperature, the instrument, together with its non-interchangeable accessory (if any), shall comply with its accuracy requirements; however, the overload shall not be repeated.
The continuous overload test shall be carried out under reference conditions except for current and voltage. The test shall be carried out with PF = 1.
5.5.3.2 Overloads of short duration
5.5.3.2.1 For the recommended test, see lEG 60051-9.
Wattmeters and varmeters, together with their non-interchangeable accessory (if any), shall be subjected to overloads of short duration.IEC 60051-3 pdf download.