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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Please contact the Customer Service Centre see below for further information. It is particularly important to observe, during successive tests, possible changes in the short-circuit reactance measured after each test, which may be progressive or tending to vanish. For other transformers with star-zigzag connection, the method of switching on is subject to agreement between the manufacturer and the purchaser.
For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. Particular requirements and tests for isolating transformers and power supply units incorporating isolating transformers.
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During the tests, winding temperature may increase owing to the circulation of the shortcircuit current. For star-connected windings, the singlephase voltage is supplied between one line terminal and the other two line terminals connected together. Scame solutions for charging systems. Particular requirements and tests for safety isolating transformers and power supply units incorporating safety isolating transformers.
This aspect shall be taken into consideration when arranging the test circuit for transformers of category I. 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 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 of the winding leads, taps, alignment of spacers and configuration of the end insulation components, etc.
NOTE At the zigzag connected windings, the short-circuit current for a single-line-to-earth fault may reach considerably higher values than at the three-phase fault. NOTE 1 At the end of the tests, if the windings are provided with tapping, the reactance must be measured for all the tapping positions at which the short-circuit tests have been carried out. U and Z t are defined as follows: However, the lightning impulse test is not required at this stage.
General requirements and tests IEC Safety of power transformers, power suply units and similar Part 2: This calculation shall be carried out in accordance with the requirements of 4. Nevertheless, if agreed between the purchaser and the manufacturer, it is permissible to test 60 Hz transformers with a 50 Hz power supply and 50 Hz transformers with a 60 Hz power supply provided that the prescribed test current values, as required in 4.
Protection accessories, such as a gas-and-oil-actuated relay and pressure relief device, shall be mounted on the transformer during the test. IEC Series moving and fixed: Table of physical and chemical constants — Kay and Laby — 15 edition, Longmans, CombiFinder Discover how to find in thousands configurations, the Combination unit for you.
With regard to tap-changer position and test sequence, the same procedure as described for transformers of categories I and II is recommended.
INTERNATIONAL STANDARD IEC 60076-5
600776-5 order to avoid injurious overheating, an appropriate time interval shall occur between successive overcurrent applications. CombiWizard Identifies the products compatible with Scame material. Reference number IEC Ability to withstand short circuit YEAR.
In order to consider the transformer as having passed the short-circuit test, the following conditions shall be fulfilled: Large power transformers sometimes cannot be tested according to this standard due, for example, to testing limitations.
However, the on-load tap-changer is not required to be capable of switching the short-circuit current. GSM based remote monitoring of 8 parameters of transformer. 6007-65, before dismantling, it is suggested that additional diagnostic means are applied see note 1 of 4.
General requirements for basic safety and essential performance. Identifies the requirements for power transformers to sustain without damage the effects of overcurrents originated by external short circuits.
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Table 2 — Short-circuit apparent power of the system Highest voltage for equipment, U m Short-circuit apparent power kV MVA Current European practice 7,2; 12; 17,5 and 24 36 52 and 72,5 and 600765 1 3 6 10 20 30 35 40 60 83 Current North American practice 1 5 15 15 25 30 35 40 60 83 NOTE If not specified, 6006-5 value between 1 and 3 should be considered for the ratio of 6076-5 to positive-sequence impedance of the system.
This last value of reactance is accepted as the final value when determining compliance with the requirements of the standard. NOTE 2 Transformers falling in the upper range of category II and having highest voltage for equipment U m not exceeding 52 kV deserve particular attention and may require an adjustment of the above reactance variation limit.
Iwc 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 These characteristics shall be specified by the purchaser in his enquiry.
Missing page numbers correspond to the Frenchlanguage pages. Any divergence between the IEC Standard and the corresponding national or regional standard shall be clearly indicated in the 600766-5. For categories I and II single-phase transformers, the number of tests shall be three. In this context, a check of the axial compression of the windings could be useful.
If the short-circuit apparent power of the system is not specified, the values given in table 2 shall be used. Electrodynamic hazard to the winding assembly may be higher either at three- or single-phase short circuit depending on the winding design.
The IEC shall not be held responsible for identifying any or all such patent rights. This increase in current should be taken into consideration when calculating the temperature rise of the zigzag winding. 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 iecc V Part 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.