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 result of the test is an estimate of the change of scale factor within the voltage application time from which the standard uncertainty contribution is obtained as a type B estimate: Special requirements on dynamic behaviour may be specified by the relevant technical committee. The principles of this 600602 apply also to higher levels but the uncertainty may be greater. Both methods are based on probability distributions of the quantities influencing the measurement and on standard uncertainties quantified by variances or standard deviations.
The uncertainty contribution related to linearity shall be considered in the calculation of measurement uncertainty when using the measuring system, see 5. For a new or repaired measuring system, performance checks shall be made at short intervals to demonstrate its stability.
Taking correlation into account is thus mainly essential for sophisticated uncertainty analysis to achieve a very 6060-2 estimation of uncertainty. The basic principles of the ISO. No requirements for this are given here, but some guidance may be obtained from Clause 8.
For impulse voltages see lEC In cases where the assumptions mentioned above in 5.
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This can be done by evaluation of a set of test data with established reference values. One of ieec methods given in 5. The uncertainty of measurement makes a clear statement on the quality of a measurement. From the convolution, the errors introduced by the measuring system for different wave shapes can be estimated Annex D.
Manolakis, Introduction to Digital Signal Processing. Preview Abstract IEC NOTE 2 The measured test voltage is required to lie within the stated tolerance of the specified test level. The numerical value of j shall be rounded to the least significant figure that could be affected by the expanded uncertainty.
Its Type A standard uncertainty is equal to the experimental standard deviation of the mean: Because there is no direct correlation between unit step response parameters and correct measurement of iiec voltages, it lost its role for the requirements of this standard, but remains important for characterizing the dynamic behaviour in connection with comparison measurements 8.
This does not preclude the free 6060-2, in course of imple- menting the standard, of necessary details, such as symbols and sizes, type or grade designations. The compliance with type test requirements can be proved by tests on a device jec the same design or sometimes be derived from manufacturer’s eic. The interference ratio shall be determined as the maximum amplitude of the measured interference divided by the output of the measuring system when measuring the test voltage.
The result of the evaluation is an estimate of a change of the scale factor.
The output of the measuring system shall be compared with idc device or system that has proven its linearity or can be presumed to be linear over the full voltage range see 5.
The result shall be in accordance with clause 7. Types of electrical measuring instruments – Part Wet tests and pollution tests, when specified, are performed as type tests. 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 ic the measurement result and its uncertainty.
The record of performance shall comprise at least the following information: NOTE 3 Proximity effects can be caused by corona and related space charge effects.
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Measuring systems which comprise only some of the above components or which are based on non-conventional principles are acceptable if they meet the uncertainty requirements specified in this document. NOTE Significant effects can be caused by visible and audible corona or leakage current.
In addition, the substitution of an equivalent measuring instrument, which satisfies the relevant lEC standard, shall be accepted. Tliis can be quantified by determination of tlie scale factor at different ambient temperatures or by computations based on properties of components.
They contribute to the scale factor values and their uncertainties as well. NOTE 2 A transmission system may be partially or completely ifc in the converting device or 60060–2 the measuring instrument. For each component of the measuring system the Type A and Type B contributions to uncertainty shall be estimated 5. These simplified procedures of clause 5 are considered sufficient for the instrumentation and measurement arrangements commonly used in high-voltage testing: For full and tail-chopped impulses: The user shall ensure that any self-made calibration is performed by competent personnel using reference measuring 60060–2 and suitable procedures.
The 60060- test report forms are related: For measurements during on-site tests see IEC Other significant influences shall also be taken into account, e. One or more ranges of clearances and respective scale factors may be assigned. The scale factors of the impulse divider index “div” and the digital recorder index “rec” and their expanded uncertainties are stated by the manufacturers as: This means that the rectangular distribution yields a larger standard uncertainty than the other distributions.
Tine preferred circuit is shown in Figure C.
Review of Indian Standards Amendments are issued to standards as the need arises on the basis of comments.
IVIeasuring systems with secondary attenuators may be calibrated on iwc setting only, provided that the load on the output of the converting device can be shown to be constant for all settings by other tests. However, this estimation may be given for defined range of measuring conditions in conjunction with the calibration certificate. Approved measuring systems comprising several pieces of equipment used inter-changeably may be covered by a single record of performance including all the combinations possible with the least amount of duplication possible.