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IEC 60076-4 PDF

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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While the output voltage of the impulse generator is determined by the test levels of the windings with respect to their highest voltage for equipment U m for the test object, the required energy storage capability is essentially dependent on the inherent impedances of the test object.

The stored data in the memory of the digitizer, however, allows for any other presentation of the same recording by zooming in or out at different time scales.

This current peak will be coincident with a voltage collapse or decay if it is due to the saturation effect. Information relating to this publication, including its validity, is available in the IEC Catalogue of publications see below in addition to new editions, amendments and corrigenda.

BS 171-4:1978, IEC 60076-4:1976

600076-4 on the form of the current trace and on the use of linear or exponential sweeps, it may be necessary to use more than one record with different sweep times. In addition, identical waveshapes at reduced and full test levels cannot be obtained.

The intention of illustrating particular faults is to give general guidance only.

The requirements for the digitizer as mentioned in 7. To make 06076-4 that we continue to meet your needs, your feedback is essential. 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.

BS , IEC – Power transformers. Specification for tappings and connections

A progressive but nevertheless total flashover across the winding under test will result in a somewhat slower voltage collapse, normally occurring in a stepped manner see figure B.

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Any turn-to-turn or part winding fault will also produce an instantaneous current peak, but with a much more rapid voltage collapse, indicating a flux blockage. Accept and continue Learn more about the cookies we use and how to change your settings. The latter part will only be comparable for reasonably identical times to chopping. Q2 Please tell us in what capacity ies you bought the standard tick all that apply. When it does occur, its effect on the voltage waveshape may be large or small depending on the amount of saturation involved.

For large values of T 1the damping idc will be large thus resulting in a relatively short time T z. Therefore, the recorded current waves are the main criteria of the test result. They comprise — isc determination of the impulse voltage waveshape; — the application of one negative polarity reduced test level impulse; — the application of three negative polarity impulses at the switching impulse withstand level without any pre-magnetization measures.

Hence, in this standard, lightning impulse testing is covered by a common text for both transformers and reactors whilst switching impulse testing is dealt with separately for the two types of equipment.

The sum of items ac and d or of items bc and dis sometimes referred to as line current. 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 in more detail. Temperature rise Part 3: In these cases, ifc value of T 2 cannot 600076-4 be adjusted according to equation A.

Alternative means of switching impulse generation or simulation such as d. Standard Number BS There will also be a change in basic frequency and there may be a decrease in amplitude.

Characteristic oscillations will also occur on the voltage wave at the moment of flashover see figures B. 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.

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The effective L thowever, may be influenced by the terminal treatment. 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. Different test 60076- levels should be compensated by appropriate attenuations to obtain the same recording level.

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This point of connection should be used as reference earth and to attain good earthing of the test object it should be connected to the reference earth by one or several conductors of low impedance see IEC Digitizers have been used in impulse testing since the s. The impulse test of the low-voltage winding is then carried out simultaneously with the test 600766-4 the associated high-voltage winding.

Kec is good practice to firmly connect this current return path to the general earth system of the test room, preferably close to the test object. International, governmental and non-governmental organizations 600076-4 with the IEC also participate in this preparation.

6006-4 three-phase reactors, the requirement, as in figure 4, that 1,5 times the voltage between phase and neutral shall be developed between phases, cannot be met.

The software can subtract the full wave and the reduced wave and show differences on an adjustable magnified scale. When resistive voltage dividers are used to check the voltage of the non-tested terminals, they should remain in the circuit because they represent a significant loading of the circuit.

Guide to lightning impulse and switching impulse testing — 6076-4 transformers and reactors Part 5: This, in fact, represents a guideline for the arrangement of the chopping circuit and may entail the introduction of additional impedance Z c in this circuit to meet the limit see figure 1.