This part of IEC applies to three-phase and single-phase power transformers (including auto-transformers) with the exception of certain categories of. NORME CE1 INTERNATIONALE IEC INTERNATIONAL STANDARD Edition Edition consolidée par l’amendement Edition . Buy IEC Ed. Power transformers Part 1: General from SAI Global.
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On theother hand, forexample, when atransformer is to becombined with previously existing units, it may be justified to specify and agree on narrower impedance tolerances. The current in the neutral and the duration 60076- applicationshould be limitedtoavoidexcessivetemperatures of metallicconstructional parts.
But the assigned values of tapping quantities are not fully defined by iiec alone. IEC consists of the following parts, under the general title: But the amount of total loss to be injected in order to determine maximum oil temperature rise shall correspond to the highest value for any tapping, even if this is other than the tapping connected for the test see also 5.
If dry-type, degree of protection see IEC In the absence of such specification, guidance on loading of transformers complying with this part may be found in IEC and iex IEC When the tapping factor deviates from unity, the tapping current for full-power tappings may riseaboveratedcurrentonone of the windings.
Dyn1 1 Example 2 A three-windingtransformer: Short-circuit impedance,impedance or range see annex C.
The test basis for all characteristics other than insulation is the rated condition, unless the test clause states otherwise. This means that the remaining tappings towards the extreme tapping are reduced-power tappings see figures l al b and I C.
S dry-type transformer a transformer of which the magnetic circuit and windings are not immersed in an insulating liquid [IEV 3. NOTE 1 For transformers with two secondary windings having the same rated power and rated voltage and equal impedance to the primary sometimes referred to as ‘dual-secondary transformers’it may be agreed to investigate the symmetrical loading case by an extra test with both secondary windings short-circuited simultaneously. Formulti-windingtransformers, severalimpedancesfordifferenttwo-windingcombinationsare to begiven with the respectivereferencepowervalues.
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The transformer shall be approximately at factory ambient temperature. The dashed lineis an example of a transformer short-circuit impedance curve which would satisfythis specification. The rated power refers to continuous loading. A moisture-removing breather is usually fitted in the connection to the atmosphere.
NOTE For multi-winding transformers, the voltage drop or rise depends not only on the load and power factor of the winding itself, but also on the load and power factor of the other windings see IEC Whenathree-phasetransformer is tested,thevoltagesshall be measuredbetweenline terminals, if a delta-connected winding is energized, and between phase and neutral terminals if a YN or ZN connected winding is energized.
Constant flux voltage variation CFVV Graphic presentation of tapping voltage variation categories: Indoor or outdoor type. Variable flux voltage variation VFVV The winding resistance measurement is made at a temperature 8. The tapping voltages in any untapped winding are inversely proportional tothe tapping factor.
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The second purpose normally requires the ‘maximum current tapping’ to be selected for the test. For those categories of power transformers and reactors which have their own 06076-1 standards, this part is applicable only to the extent in which it is specifically called up by cross-reference in the other standard.
Regarding the full presentation on the nameplate of data related to individual tappings, see clause 7.
Whetherunbalancedthree- phase loading is anticipated. The phasors are assumed to rotate in a counter-clockwise sense [IEVmodified] NOTE The high-voltage windingphasor is taken as reference,and the displacement for any otherwinding is conventionally expressed by the ‘clock notation’, that is, the hour indicated by the winding phasor when the H.
The measurements are carried out with a current not exceeding the difference between the rated currents on the low-voltage side and the high-voltage side. The temperature-rise limits are valid for all tappings, at the appropriate tapping power, tapping voltage and tapping current. Combined voltage variation CbVV The tapping quantities are: Inorder to limitthecorrespondingreinforcement of the winding in question, it is possible to specify a maximum current tapping.
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The load loss is measured with the winding at an average temperature 8. S Type of oil preservation system.
When the transformer has rated voltage applied to 600761 primary winding, and rated current flows throughtheterminals of asecondarywinding,thetransformerreceivestherelevantrated power for that pair of windings. These may be factors such as high altitude, extreme high or lowtemperature,tropical humidity, seismicactivity, severe contamination, unusual voltage or load current wave shapes and intermittent ifc. Instead of items c and dtabulation of the same type as used on the rating plate may be used to advantage see example in annex B.