Telephone: +41 22 02 11 Telefax: +41 22 03 00 E-mail: [email protected] Web: INTERNATIONAL. STANDARD. IEC. Third edition. This part of IEC identifies the requirements for power transformers to sustain without damage the effects of overcurrents originated by external short. IEC. Second edition. This English-language version is As from 1 January all IEC publications are issued with a designation in the.
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The short-circuiting of the winding may either follow post-set short circuit or precede pre-set short circuit the application of the voltage to the other winding of the transformer 4.
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U is the rated voltage U r of the winding under consideration, in kilovolts; Z t is the short-circuit impedance 600765- the transformer referred to the winding under consideration; it is calculated as follows: NOTE For auto-transformers and for transformers with short-circuit current exceeding 25 times the rated current, a short-circuit current duration below 2 s 6076-5 be adopted by agreement between the manufacturer and the purchaser. With this test arrangement, it might be convenient to mutually connect the corresponding terminals of the phases not submitted to test in order to better control their voltage, provided that this is feasible and circuitry correct.
IEC Series moving and fixed: However, in order to simulate as closely as possible the effects of repetitive short-circuit events likely to occur in service, to allow a better monitoring of the behaviour of the unit under test and to permit a meaningful judgement in connection with possible variations of the measured short-circuit impedance, it is recommended that the number of tests is as follows: With regard to tap-changer position and test sequence, the same procedure as described for transformers of categories I and II is recommended.
General requirements for basic safety and essential performance.
The results of the short-circuit reactance measurements and the oscillograms taken during the different stages of the tests shall be examined for any isc of possible anomalies during the tests, especially any indications of change in the short-circuit reactance.
Particular requirements and tests for control transformers and power supplies incorporating control transformers. Table of physical and chemical constants — Kay and Laby — 15 60067-5, Longmans, Their preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with may participate in this preparatory work.
All International European Italian Selector: Annex A is for information only.
General requirements for basic safety and essential performance IEC Safety of power 6076-5, power supplies, reactors and similar products Part 1: The text of this standard is based on the following documents: Describes the calculation procedures used to demonstrate the thermal ability of a power transformer to withstand such overcurrents and both the special test and the theoretical evaluation method used to demonstrate the ability to 60067-5 the relevant dynamic effects.
Particular requirements for isolating transformers for the supply of medical locations. Particular requirements and tests for auto transformers and power supply units incorporating auto transformers IEC Safety of power transformers, power supply units and similar Part Missing page numbers correspond to the Frenchlanguage pages.
In general, such conditions are of a more complex nature in comparison with the three-phase short circuit which can be considered the reference case for two-winding transformers see 3. Identifies the requirements for power transformers to sustain without damage the effects of overcurrents originated by external short 06076-5. Identifies the products compatible with Scame material.
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Protection accessories, such as a gas-and-oil-actuated relay and pressure relief device, shall be mounted on the transformer during the test. In this case, the factor k is found 600765 oscillograms of the line currents.
However, for transformers of category I, the repetition of the routine tests with the exception of the dielectric tests may be omitted. For all transformers, excluding the case given in 3.
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To make sure that we continue to meet your needs, your feedback is essential. U and Z t are defined as follows: It describes the calculation procedures used to demonstrate the thermal ability of a power transformer to withstand such overcurrents and both the special test and the calculation method used to demonstrate its ability to withstand the relevant dynamic effects. Safety of transformers, reactors, power supply units and similar products for supply voltages up to 1 V Part Account shall be taken of the different forms of system faults that can arise in service, for example line-to-earth faults and line-to-line faults associated with the relevant system and transformer earthing conditions; see IEC Unless otherwise specified, the three tests on a single-phase transformer with tappings are made in a different position of the tap-changer, i.
The test shall be carried out in accordance with the requirements in 4. NOTE 3 Temporary sparks over tank joints may occur at the energizing stage and internal sparking at the frame joints at the energizing and short-circuit stages.