The text of the International Standard IEC was approved by ISO/ IEC Guide Uncertainty of measurement -. Find the most up-to-date version of IEC at Engineering also reflected by the older editions of the relevant standard IEC For good practice in HV test fields, this Sect. on HV measurement and uncertainty .
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The 600602 method assumes that the step response of the measuring system is correctly measured and the input waveform used in the calculation is representative of the real impulse waveforms to be measured. The reference level within the reference level epoch s for which the system is to be approved 60060-2 not differ from the value of the step response at the time: In this case another method suitable for the linearity test shall be chosen.
NOTE 2 The recommended minimum value for the assigned operating time is 1 h. Requirements for instruments lEC Instruments and software used for measurement in high-voltage impulse tests — Part 2: Mj,g is the combined standard uncertainty of the mean front time ieec, Ar.
It is recommended to apply a substitute test object between the two kec systems. Other contributions can be important in individual cases and the information given here is for guidance only. The resolution does not need to be considered again, in full, but rather only in a small portion as a residual Type B uncertainty.
For the comparison of peak values a sphere gap according to lEC may be used. The error of the reference measuring system is assumed to be negligible.
The result of the test is the change of scale factor from which the standard uncertainty contribution of type B is estimated: NOTE 2 In general, the front times are evaluated from the same records of N and X, used to evaluate the peak values for determining the scale factor 5. In impulse voltage measurements they are usually taken from 600602 response measurements Annex C.
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The scale factor shall be determined over the assigned measurement range by one of the following methods described in 5. NOTE 3 The evaluation of Type B uncertainties requires extensive knowledge and experience of the relevant physical relationships, influence quantities and measurement techniques. Additional information on the proximity effect and long-term stability is given by the manufacturer.
For dated references, only the edition cited applies. This scale factor may also be determined as the product of the scale factors of the components. For cases where temperature correction has been applied, the uncertainty Ugc of the temperature correction factor may be taken as the uncertainty irc.
The amplitude- frequency response outside this range is given for information only. Investigation of the proximity effect in the performance test is only necessary if the type test data are not sufficient. Comparative measurement The satisfactory performance of a reference measuring system shall be shown by calibration by comparison measurements at the relevant test voltage against a low-uncertainty reference measuring kec, which is itself traceable to the standards of a National IVIetrological Institute.
The model equation can be evaluated manually, using the equations given in Annex A, or with the aid of special software which should be validated for calculating uncertainties. However, if the digital recorder is then used during 6060-2 impulse voltage test to obtain a single measurement value, the limited resolution needs to be considered in a Type B uncertainty. NOTE 2 In some cases, the relative standard uncertainty of a measurement may be appropriate.
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Users of Indian Standards should ascertain that they are in possession of the latest amendments or edition by referring to the latest issue of ‘BIS Catalogue’ and ‘Standards: NOTE The requirement on the lower limit frequency can be verified at the frequency of its supply voltage in many cases. NOTE Significant effects can be caused by visible and audible corona or leakage current.
Bureau of Indian Standards BIS is a statutory institution establisined under tine Bureau of Indian Standards Act, to promote harmonious development of the activities of standardization, marking and quality certification of goods and attending to connected matters in the country. No requirements for this are given here, but some guidance may be obtained from Clause 8. General terms relating to electrical measurements – Part To obtain the uncertainty of measurement of the approved measuring system, those of the irc should be combined as demonstrated in Annex B.
Routine tests shall be performed on each component. For example, 06060-2 voltage divider is characterized by the voltage ratio and its uncertainty in the assigned measurement ranges used. Additionally step response parameters evaluated according to Annex C shall satisfy the recommendations of Table 6. For each component of the measuring system the Type A and Type B contributions 6000-2 uncertainty shall be estimated 5.
NOTE 4 In certain cases, it may be necessary to measure transient voltages superimposed on an alternating voltage. In cases where input quantities are uncorrelated, the sign need not be considered further since 6006-2 the quadratic value of standard uncertainties is used in the next steps. The result shall be in accordance with clause 7. The relevant data should be kept for inspection in the form of a table equal or comparable to Table A. NOTE 2 The environment in which a measuring system functions, its clearances to live and earthed structures and the presence of electric or magnetic fields may significantly affect the measurement result and its uncertainty.
The initial tests consist of type tests performed on a component or system of the same design and routine tests performed on every component or system. Tests for assessing contributions to uncertainty which are usually considered are summarized in Table 5.
The number of significant places retained in the rounded off value should be the same as that of the specified value in this standard.
When a switching impulse is used, ff is equal to T which is the time to peak of the impulse. It is used for computer-aided calculation 600600-2 digital impulse waveforms. For an impulse measuring system, the performance tests also show that its dynamic performance is adequate for the specified measurements and that the level of any interference is less than the specified limits.
The linearity of the approved measuring system shall preferably have been established with the reference method during calibration given in 5.
IEC Guide and examples lec how to determine uncertainties in high voltage measurements are presented in the following clauses.