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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600766-4 on types of voltage dividers, their applications, accuracy, calibration and checking is given in IEC Examples of such transfer function are given in figure B. More details in this respect are given in 7.
Accept and continue Learn more about the cookies we use and how to change your settings. Impedance earthing of the non-tested terminals of the winding under test may then be applied. For wavetail adjustments, the test object can be represented by its effective inductance as indicated in figure A. Enter the exact number of the standard: Alternative means of switching impulse generation or simulation such as d.
For current recordings, it may be advantageous to use, in addition, a shorter sweep time so as to be able to monitor the initial capacitive current 600766-4 more detail.
Nearly the same considerations apply for the adjustment of the switching impulse front time. Ability to withstand short-circuit Part 8: Having eliminated or explained the above sources of discrepancies, variations in the waveshape of voltage or current records between reduced and rated test voltage or between successive records at rated test voltage, which cannot be proved to originate in the test circuit or in non-linear resistors within the test object, are evidence of insulation failure from the ie.
Hence, it is not possible to state a time to chopping which is the most onerous either in general or for any particular transformer or reactor.
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The value of the test voltage is determined according to the principles of IEC Likewise, incipient faults at or near the terminal under test may also give only small indications on the oscillograms or digital recordings. However, practice has been to specify reactor waveshapes as for transformers, that is, by T 1T d and T z see figures 3b and B.
Different test voltage levels should be compensated by appropriate attenuations to obtain the same recording level. Hence, the normal impulse test procedures as used for lightning impulse tests are required.
Power transformers, Windings, Short-circuit current tests, Impedance measurement, Electric load, Temperature rise, Voltage fluctuations, Magnetic fields, Rated power, Phase electricThree-phase transformers, Single-phase transformers, Transformers, Tappings electricalAutotransformers.
The current flowing to earth through the tested winding can additionally be used. This series and sometimes also discrepancies after the peak, which may also originate from the with multiple parallel stage operation, if the discharge circuits are not coincident in may require new setting of the discharge gaps on generators which have both parallel gaps. Q2 Please tell us in what capacity ies you bought the standard tick all that apply.
NOTE 2 The changes in waveshape shown above are more marked than those which generally result from the presence of non-linear resistors. Test methods for transformer neutrals are given in IEC Click to learn more.
IECHigh-voltage test techniques — Part 1: When the capacitance to earth is large compared to the through capacitance, an initial distribution similar to curve S in then graph will occur and the final distribution can again be assumed to curve Q.
However, the literature and experience regarding transfer function analysis was for many years contradictory. According to equation A.
The presentation of the recordings for the acceptance test are the same as for the presentation of oscillograms in 7. For the passive network of a transformer, both the admittance function and the impedance function are considered as a characteristic function in the frequency domain and should be independent of the waveshape.
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. Jec 3 in figure A. The preferred method of test is that of direct application although in special cases where the intermediate or low-voltage winding cannot, in service, be subjected to lightning overvoltages from the system connected to it, the “transferred surge” method may alternatively be employed.
Specification for tappings and connections Status: Electronic Single-Phase kWh Meter. It should be long enough to ensure approximately uniform distribution throughout the tested winding. For three-phase reactors, the requirement, as in figure iiec, that 60076- times the voltage between phase and neutral shall be developed between phases, cannot be uec. Digital recording offers the potential for mathematical interpretation of the results and allows additional mathematical processing to be used, for example, for fault analysis in recordings.
For 6007-4 earthed terminals, only the leakage inductance determined by the short-circuit impedance is involved. Again it is possible to produce excessively high voltages to earth in parts of the winding.
However, resistive loading causes a significant lengthening of the wavefront at the non-tested terminals, 60076–4 in a phase-to-phase voltage of less than 1,5 U. Non-gapped, non-linear resistors may produce a 60076-44 and progressive development or change with increasing voltage levels see figure B. The final distribution ifc be similar to curve Q, where all, or almost all, of the voltage appears across the resistor. In this check, voltage may be determined by means of a sphere gap or by comparative measurement with another approved device.
Some possibilities have been identified in 9. Impulse currents may be recorded and will in many cases give additional information about a fault. This test configuration applies the proper waveshape to the line-end insulation and is suitable for earth current measurements, although the resistance may reduce slightly failure detection sensitivity.