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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A report containing the result of the routine tests shall be available at the beginning of shortcircuit tests. To make sure that we continue to meet your needs, your feedback is essential. NOTE 2 Any differences between the results of measurements made before and after the test may be used as a criterion for determining possible defects. 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 Identifies the requirements for power transformers to sustain without damage the effects of overcurrents originated by external short circuits.
Consolidated editions The IEC is now publishing consolidated versions of its publications. This calculation shall be carried out in accordance with the requirements of 4.
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Particular requirements for isolating transformers for the supply of medical locations. The results of the short-circuit reactance measurements and the oscillograms ief 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. NOTE The mounting of accessories having no influence on the behaviour during short circuit e. If the pre-set short ice is used for a transformer with single-concentric windings, the supply should preferably be connected to the winding further from the core.
Reference number IEC Particular requirements and tests for auto transformers and power supply units incorporating auto transformers.
For transformers having more than two windings, auto-transformers, booster transformers and transformers directly associated with other apparatus, the overcurrents are calculated in accordance with 3.
External short circuits are not restricted to three-phase short circuits; they include line-to-line, double-earth and line-to-earth faults. In this case, the factor k is found from oscillograms of the line currents.
Particular requirements and tests for safety isolating transformers and power supply units incorporating safety isolating transformers. This procedure requires that the voltage of the test supply is suitably adjusted with respect to the rated voltage of the transformer.
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 Scame solutions for charging systems. U is, unless otherwise specified, the tapping voltage 2 of the winding under consideration, in kilovolts; Z t is the short-circuit impedance of the transformer referred to the winding and the tapping under consideration, in ohms per phase.
These measurements and tests serve as references for the detection of faults.
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Large power transformers sometimes cannot be tested according to this standard due, for example, to testing limitations. Particular requirements irc separating transformers for general use. The short-circuiting of the winding may either follow ie short circuit or precede pre-set short circuit the application of the voltage to the other winding of the transformer 4. Another method for determining the phase current in a delta-connected winding is by suitably interconnecting the secondary windings of the current transformers measuring the line currents.
NOTE It may not be economical to design auxiliary windings to withstand short circuits on their terminals. When calculation and design consideration is selected, validation by comparison with a previously tested similar transformer or tests on representative models is 600076-5.
Information on the subjects under iex 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 6076-5 following: For three-phase tests on delta-connected windings, this condition is obtained by switching on when the line-to-line voltage passes through zero.
The coefficients are based on the following material properties: Particular requirements and tests for control transformers and power supplies incorporating control transformers IEC Safety of transformers, reactors, power supply units and similar products for supply voltages up to 1 V Part Their preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with may participate in this preparatory work.
The IEC collaborates closely with the International Organization for Standardization ISO in accordance with conditions determined by agreement between the 600765- organizations. The choice of the test duties to ifc performed should be made, as a rule, on the basis of the analysis of the results of calculations of electrodynamic forces occurring in all possible fault cases.
This last value of reactance is accepted as the final value when determining compliance with the requirements of the standard. General requirements for basic safety and essential performance.
The requirements apply to transformers as defined in the scope of IEC Table of physical and chemical constants — Kay and Laby — 15 edition, Longmans, The single-phase voltage during the test shall be equal to voltage between phases during the three-phase test.
This increase in current should be taken into consideration when calculating the temperature rise of the zigzag winding.
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Medical electrical equipment Part 1: Unless otherwise specified, the three tests on a single-phase transformer with tappings are made in a different position of the tap-changer, i. Safety of power transformers, power 60067-5 units and similar Part 2: It describes the calculation procedures used to demonstrate the thermal ability of kec 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.
However, these high values are limited, in the two limbs concerned, to a half of the coil and furthermore the currents in the other star-connected winding are lower than for 60067-5 three-phase short circuit. Documents Flashcards Grammar checker. Electrodynamic hazard to the winding assembly may be higher either at three- or single-phase short circuit depending on the winding design.
The two windings can be supplied either from the same power source or from two separate and synchronized power sources.