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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Instead of iiec the expanded uncertainty and coverage factor, one may find uec statement on the confidence level, e. One of the methods given in 5. Taking correlation into account is thus mainly essential for sophisticated uncertainty analysis to achieve a very accurate estimation of uncertainty.
Manolakis, Introduction to Digital Signal Processing. The interval between performance tests shall be based on evaluation of past stability of the measuring system. The uncertainty of measurement makes a clear statement on the quality of a measurement.
A major requirement for a converting device, a transmission system, and a measuring instrument used in a measuring system 60060-22 stability within the specified range of operating conditions so that the scale factor of the measuring system remains constant over long periods. The main assumptions are as follows: However, many systems which could be approved for measurements of peak value and time parameters cannot be approved for measurements of oscillations.
NOTE 2 Uncertainty of voltage measurement should not be confused with the tolerance of a specified test voltage.
Scale factor of an AC measuring system comparison method An AC measuring system of rated voltage kV, denoted by X, is calibrated by an accredited calibration laboratory in the test laboratory of the customer.
In case m x is unknown, it shall be calculated from other relevant uncertainty data or be 6060-2 on the basis of experience. In case of impulse voltages, waveforms of two or more different front times covering the range of the nominal epoch shall be applied. NOTE 3 Investigation of the proximity effect in the performance test is only necessary if the type test data are not sufficient.
NOTE 1 In order to reproduce, in the recorded curve, oscillations that may be superimposed on an impulse, the relevant upper limit frequency may be several MHz.
In contrast to measurements of lightning impulse voltage see 8. NOTE 1 Different values for iigg may be given for different ranges of distances.
The maximum deviation is a. NOTE If the calibration is performed over the full assigned measurement range 5. NOTE uec The measured test voltage is required to lie within irc stated tolerance 6000-2 the specified test level. These conditions are fulfilled in many calibrations of voltage measuring systems.
The basic principles of the ISO. If it is greater, then a new value of the assigned scale factor shall be determined in a performance test. Simultaneous readings shall be taken on both systems. The law of propagation of uncertainty thus applies to both types of the model function for uncorrelated input quantities.
For example, a voltage divider is characterized by the voltage ratio and its uncertainty in the assigned measurement ranges used. Requirements for instruments lEC Instruments and software used for measurement in high-voltage impulse tests — Part 2: NOTE 2 Preferably one measuring system is used to measure all of the required quantities, i.
The results of the type and routine tests can be taken from manufacturer’s data.
For many measuring systems, information on the transmission system as well as high-voltage and ground-return arrangements are important. The uncertainty limits shall not be exceeded in the presence of ripple, the magnitude of which is within the limits given in lEC For details see also the related clauses for measurement of alternating voltages Clause 7.
The coupling between the test and measuring circuits should be negligible. The proximity effect need not be investigated as the divider is located outside the minimum clearance specified by the manufacturer. The converting device shall not be connected between the voltage source and the test object.
Full text of “IS/IEC High – Voltage Test Techniques, Part 2: Measuring Systems”
The limits on uncertainties of measurements stated in this standard apply to test levels stated in IEC To obtain the uncertainty of measurement of the approved measuring system, those of ifc components should be combined as demonstrated in Annex B. Number pairs in Ihe diagram sliow tlie normalised frequency and tine corresponding permitted deviation from tine ideal response at the corner points of the limit lines.
Other contributions can be important in some cases and so shall be considered in addition. NOTE 2 The period of voltage application should not be longer than the assigned operating time, but iiec be limited to a time sufficient to reach equilibrium. Routine tests shall be performed on each unit. The input voltage used for calibration should be of the same type, frequency or waveform as voltages 600060-2 be measured.
For step response requirements of impulse voltage reference measuring systems, see The resolution does not need to be considered again, in full, but rather only in a small portion as a residual Type B uncertainty. NOTE 1 As an example, the result of a voltage measurement is stated in one of the following ways: Some guidance on determining uncertainty contributions, that need to be considered, and on their combination is given in Clause 5 and Annexes A and B. The error of the reference measuring system is assumed to be negligible.
Finally, the complete result of the calibration is expressed as follows: NOTE Long intervals between performance tests can increase the risk of an undetected change in the measurement system. Performance test shall be made after major repairs to the measuring system and whenever a circuit arrangement that is beyond the limits given in the record of performance is to be used.