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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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: CombiFinder Discover how to find in thousands configurations, the Combination unit for you.
INTERNATIONAL STANDARD IEC
International, governmental and non-governmental organizations liaising with the IEC also participate in this preparation. This increase in current should be taken into consideration when calculating the temperature rise of the zigzag winding. For other transformers with star-zigzag connection, the method of switching on is subject to agreement between the manufacturer and the purchaser.
This applies, for example, to unit generator transformers if the connection between generator and transformer is constructed in such a way that the possibility of line-to-line or double-earth faults in this region is negligible.
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In this case, the factor k is found from oscillograms of the line currents. NOTE In connection with the economical impact of the cost of a transformer of category III and the cost implication of any thorough visual inspection extended to the inner parts of the unit, it is recommended that a series of photographs be taken of the position iiec the winding leads, taps, alignment of spacers and configuration of the end insulation components, etc.
NOTE The mounting of accessories having no influence on the behaviour during short circuit e. The requirements apply to transformers as defined in the scope 60076-5 IEC All International Uec Italian Selector: If the pre-set short circuit is used for a transformer with single-concentric windings, the supply should preferably be connected to the winding further from the core.
Q2 Please tell us in what iex ies you bought the standard tick all that apply. In order to avoid injurious overheating, an appropriate time interval shall occur between successive overcurrent applications. The oscillograph can be set to record the phase currents.
INTERNATIONAL STANDARD IEC 60076-5
Particular requirements and tests for auto transformers and power supply units incorporating auto transformers. 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.
NOTE 2 For star-connected windings with non-uniform insulation, it is necessary to check whether or not the insulation of the neutral is sufficient for single-phase testing. Their preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with may participate in this preparatory work. Another method for determining 600076-5 phase current in a delta-connected winding is by suitably interconnecting the secondary windings of the current transformers measuring the line currents.
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Scame solutions for charging systems. For transformers of category III, an agreement between the manufacturer and the purchaser is always needed with regard to the number of tests and the position of the tap-changer. For all transformers, excluding the case given in 3. In these cases, the testing conditions shall be agreed between the purchaser and the manufacturer. To make sure that we continue to meet your needs, your feedback is essential.
General requirements for basic safety and essential performance. In the case of single-phase transformers connected to form a three-phase bank, the stabilizing winding shall be capable of withstanding a short-circuit on its terminals, unless the purchaser specifies that special precautions will be taken to avoid the risk of line-to-line short circuits.
In this isc, a check of the axial compression of the windings could be useful.
When calculation and design consideration is selected, validation by comparison with a previously tested similar transformer or tests on representative models is required. General catalogue Go to interactive catalogue. The factor k accounts for the initial offset of the test current and to-r. 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 may be adopted by agreement between the manufacturer and the purchaser.
Particular requirements and tests for isolating transformers and power supply units incorporating isolating transformers. NOTE 3 If, for star-connected windings, the power supply is insufficient for the single-phase testing described above and the neutral is available, the manufacturer and the purchaser may agree upon the use of single-phase power supply between line terminal and the neutral, provided that neutral is capable of carrying the relevant current.
Missing page numbers correspond to the Frenchlanguage pages. If any of the above conditions are not met, the unit shall be dismantled, as necessary, to establish the cause of the deviation. For undated references, the latest edition of the normative document referred to applies. NOTE 2 Random gas-and-oil-actuated relay tripping may occur during the tests due to vibration.
Annex B forms an integral part of this standard. CombiWizard Identifies the products compatible with 600076-5 material. A report containing the result of the routine tests shall be available at the beginning of shortcircuit tests.
Fort Hood Sentinel Advertisement. NOTE Iiec may not be economical to design auxiliary windings to withstand short circuits on their terminals. For three-phase tests on delta-connected windings, this condition is obtained by switching on when the line-to-line voltage passes through zero. This time shall be defined by agreement between the manufacturer and the purchaser. In such cases, the overcurrent level must be limited by appropriate means, such as series reactors 60076- in some instances, fuses.
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.
In this case, provision should be made by the purchaser to limit the overcurrent to the maximum value determined by the manufacturer and stated on the rating plate.
Safety of power transformers, power supply units and similar Part NOTE Equations ieec and 5 are based on adiabatic conditions and are valid for only a short time duration, not exceeding 10 s.
The method is advantageous in preventing any saturation of the core and will reduce the power requirement of the supply. The results of the short-circuit reactance measurements and the oscillograms taken during the different stages of the tests shall be examined for any indication of possible anomalies during the tests, especially any indications of change in the short-circuit reactance.
U and Z t are defined as follows: Particular requirements and tests for isolating transformers and power supply units incorporating isolating transformers IEC Safety of transformers, reactors, power supply units and similar products for supply voltages up to 1 V Part Unless otherwise specified, the three tests on a single-phase transformer with tappings are made in a different position of the tap-changer, i.
Application guide IEC This circumstance is not significant for the ability of the transformer to withstand short-circuit iiec combustible gas is found in the relay.