IEC Power transformers – Part 4: Guide to the lightning impulse and switching impulse testing – Power transformers and reactors. Edition Guide to the lightning impulse and switching impulse testing –. Power transformers and reactors. Reference number. IEC (E). INTERNATIONAL. Buy IEC Ed. Power transformers Part 4: Guide to the lightning impulse and switching impulse testing – Power transformers and reactors from SAI.
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On multiple layer windings, the layer impedance may damp the collapse normally to the extent that it does not oscillate around zero see figure B. On-line information is also available on recently issued publications, withdrawn and replaced publications, as well as corrigenda. Insulation levels, dielectric tests 06076-4 external clearances in air Part 4: When this 600766-4 is measured on the winding to which the impulse voltage is directly applied, whether or not this is the winding on which the specified test voltage level is to be achieved, the current comprises three parts: The effective L thowever, may be influenced by the terminal treatment.
Requirements for instruments IECDigital recorders for measurements in high-voltage impulse tests — Part 2: With the application of digital recorders in highvoltage testing of power transformers, a warning with respect to amplitude and time parameters should be given with respect to the evaluation of non-standard waveshapes. It should, however, be sufficiently long to ensure essentially uniform distribution of voltage. Discrepancies of any kind are of concern and should be investigated.
60076- the test report see clause 11 one pertinent recording is normally sufficient for acceptance tests; for diagnostic testing, however, several records with different sweep times may be required. For example, edition numbers 1. Find Similar Items This product falls into the following categories. One pertinent recording see clause 11 is normally sufficient for acceptance tests. Currents may increase or decrease and the direction of the change together with the method of fault detection will give guidance on the nature and location of the fault see figure B.
Differences are in details only, such as values of resistors and capacitors and the terminal connections of the test object. Item 3 in figure A.
Information on the subjects under consideration and work in progress undertaken by the technical committee which has prepared this publication, as well as the list of publications issued, is also available from the following: For transformers, any part-winding defect turn-to-turn failure, disc-to-disc breakdown, or breakdowns in tapping windings will result in a flux blockage and will easily be detected by voltage and current records.
This current peak will be coincident with a voltage collapse or decay if it is due to 6007-4 saturation effect. The other terminal of this phase winding should be earthed.
For diagnostic purposes, however, the software of the system offers the possibility to examine the wave over the entire sampling time, or part of the wave as all information is stored in the computer memory. Nearly the same considerations apply for the adjustment of the switching impulse front time.
60706-4 The load capacitance will then reduce the adverse effects of a small series resistor R s. When using digital recording techniques, the transfer function analysis as described in clause 10 may be helpful to eliminate this confusion see figure B.
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These quantities are illustrated in figure 3a. Consolidated editions The IEC is now publishing consolidated versions of its publications.
This problem oec be solved to some extent by the use of large capacitance within the generator, by parallel stage operation, by adjustment of the series resistor or by specific test connections of the terminals of windings not under test or, in addition, of the non-tested terminals of windings under test.
You oec experience issues viewing this site in Internet Explorer 9, 10 or However, this sensitivity is accompanied by the possibility of the recordings indicating a number of effects not directly associated with failure. The solution for your HV testing needs – Hydro.
The test equipment used in lightning and switching impulse applications is basically the same. These samples should be presented directly as raw data for evaluating waveshape parameters see 7. The faster, easier way to work with standards. Except at the start of the wave or, in the case of transformers, in the vicinity of core saturation, sharp changes of current occurring at the same time as any distortion of the voltage wave are indicative of failure. Proof that these differences are indeed caused by operation of these devices should be demonstrated by making two or more reduced full-wave impulse tests at different voltage levels to show the trend in their operation.
INTERNATIONAL STANDARD IEC 60076-4
Likewise, incipient faults at or near the terminal under test may also give only small indications on the oscillograms or digital recordings. The software can subtract the full wave and the reduced wave and show differences on an adjustable magnified scale. For dated references, only the edition cited applies. Core saturation does not usually occur on reduced-level voltage applications and may not even occur on full-level applications.
It is 600764- in acceptance testing, to record at least uec of these transients in addition to the applied test voltage: However, this may not always be possible even with the highest values of resistors. The value of the test voltage is iev according to the principles of IEC Evidently, the value of C t for tail considerations is of minor importance in most practical cases see equation A.
BS , IEC – Power transformers. Specification for tappings and connections
These techniques show promise but interpretation of the results is not yet proven nor unambiguous. This is a skilled task and it is often difficult to decide the significance of discrepancies, even with considerable experience, because of the large number of possible disturbance sources.
However, problems might arise for the fast rising part of the waveshape where the proper time adjustment of the two curves can be difficult to accomplish. For directly earthed terminals, eic the leakage inductance determined by the short-circuit impedance is involved.