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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NOTE The requirement on the lower limit frequency can be verified at the frequency of its supply voltage in many cases. IEC Guide and examples of how to determine uncertainties in high voltage measurements are presented in the following clauses.
Full text of “IS/IEC High – Voltage Test Techniques, Part 2: Measuring Systems”
They are determined according to 5. NOTE A measuring system has a unit step response for each reference level. In order to obtain the uncertainty of the complete measuring system, the user has to consider additional uncertainty contributions, either taken from the records of performance of the divider and recorder, or determined by additional tests.
Preview Abstract IEC Special requirements on dynamic behaviour may be specified by the relevant technical committee. The complete linearity test shall be made within sufficiently short time that atmospheric conditions do not change and hence corrections need not be used. It describes how the output estimate y is influenced by small variations of the input estimate X. When the step is generated using a repetitive generator, the duration of the step, and of the interval between steps shall be chosen such that no additional errors are introduced with respect to a single pulse.
A measuring system with a response parameter T equal or less than several tens of nanoseconds can be considered suitable see Annex C.
Conditions significant for the result of the calibration of the approved measuring system shall be included in the record of performance. Part 2 Evaluation of software used for the determination of the parameters of impulse waveforms Degree of Equivalence Identical to lEC For full and tail-chopped impulses: In cases where a number of performance test results are available, the long-term stability can be characterised by the type A contribution: High-voltage test techniques – Partial discharge measurements I EC Correlation occurs when, for example, the same instrument is used for measuring two or more input quantities.
NOTE 1 Parasitic coupling may need to be investigated.
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Other contributions can be important in some cases and so shall be considered in addition. When the transient voltage drop during pollution testing is measured, the time constant of the measuring system shall be less than one third of the 600060-2 time of the transient. The electric-field measuring system shall provide a response suitable for the type of voltage being measured.
The user shall ensure that any self-made calibration is performed by competent personnel using reference measuring systems and suitable procedures. In some cases it may, however, be necessary or desirable to evaluate uncertainties in a more complex manner.
Routine tests shall be performed on each unit. If it is greater, then a new value of the assigned scale factor shall be determined in a performance test.
In eic the step response of the measuring system shall be recorded according to Annex C.
The parasitic coupling between the test and measuring circuit should be minimized. NOTE 4 In certain cases, it may be necessary to measure transient voltages superimposed ic an alternating voltage. IVIeasuring systems with secondary attenuators may be calibrated on one 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.
This allows a uniform treatment of both categories of uncertainties and an evaluation of a combined standard uncertainty of the measurand. As the consequence of a slower step response, the front time of the output impulse becomes larger.
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The relevant data should be kept for inspection in the form of a table equal or comparable to Table A. The user shall apply tests given in this standard to qualify their measuring system s. The limits on uncertainties of measurements stated in this standard apply to test levels stated in IEC 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 2 This method is applicable to alternating voltage and to impulse voltages. One of the methods given in 5.