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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6076-1 U is the voltage rated voltage or tapping voltage of the winding to which Z a n d Zr, belong. The specification of these data may be accomplished in two different ways: If the transformer has more than one set of ratings, depending upon different connections of windings which have been specifically allowed for in the design, the additional ratings shall all be given on the rating plate, or separate rating plates shall be fitted for each set.
The extreme categories of tapping voltage variation are: The measured no-load loss is Pm,and the corrected no load loss is taken as: If the connections can be changed inside the transformer, this shall be indicated on a separate plate or with duplicate rating plates.
The relative value is also equal to the ratio between the applied voltage during a short-circuit measurement which causes the relevant rated irc or tapping current to flow, and rated voltage iev tapping voltage.
IEC 1 Power transformers General | Duy Nguyen –
Whethertransformerswillbesubjectedtofrequentovercurrents,forexample,furnace transformers and traction feeding transformers. NOTE 3 For the series winding of a three-phase booster transformer which is designed as an open winding see 3. The low- voltage winding is V star-connected wiih neutralbrought out. In a multi-winding transformer, the statements apply to the combination of the tapped winding with either of the iex windings.
An environment not exposed to seismic disturbance 6007-1 would otherwise require special consideration in the design. If for some reason the design has unequal steps, this shall be indicated in the tender.
If oil-immersedtype,whethermineraloil or synthetic insulating liquid. Whenatransformeris specified for installation at high altitude, this shall be indicated, together with information on either the reduced temperature rise figures valid under normal ambient conditions, or thereducedloadingwhichwillresultinnormaltemperaturerise at the highaltitude standard transformer with normal cooling capacity.
Theresultsarere-calculated,allocatingimpedancesandlossesto individualwindings see IEC Contactbetweentheoilandexternalairmaysometimesbediminished or prevented 3.
If a lightning impulse voltage test is required, whether or not the 600761 is to include chopped waves see IEC In general, it is usually not accessible for direct measurement in testing. I militaire comme cl tableaux, diagrammes, graphiques, autre s I une D tion la P This means that the remaining tappings towards the extreme tapping are reduced-power tappings see figures l al b and I C.
IEC – Power Transformers Package
If test methods are not prescribed in this standard, or if tests other than those listed above are specified in the contract, such idc methods are subject to agreement. For those categories of power transformers and reactors which have their own IEC standards, this iecc is applicable only to the extent in which it is specifically called up by cross-reference in the other standard. Further windings, if existing, are open-circuited NOTE 1 For a two-winding transformer there is only one winding combination and one value of load loss.
The quantity ‘highest voltage for equipment’ which characterizes the insulation of the winding, is also kV see IEC For selection of tapping for the test, see 5.
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Themeasuredvalue of load loss shallbemultipliedwiththesquare of the ratio of rated current tappingcurrent to testcurrent. Tolerances on voltage ratios and short-circuit impedances as left to agreement in table 1, or deviating from values given in the table.
CFVV 600766-1 for tappings with tapping factors below the maximum voltage tapping factor. If the cooling system is OF or OD, the pump may be used to mix the oil.
When the tapping factor deviates from unity, the tapping current for full-power tappings may riseaboveratedcurrentonone of the windings. Full-power tappings – reduced-power tappings All tappings shall be full-power tappings, except as specified below. Therequirements of this clause should be used as far as applicable. Transformers having large tapping ranges, particularly if the range is asymmetrical, may also requirespecialconsideration.
The windingtemperatureshallbemeasuredbysensorsplaced at representativepositions, preferably inside the set of windings, for example, in a duct between the high-voltage and low- voltage windings.
In the absence of such specification, guidance on loading of transformers complying with this part may be found in IEC and in IEC S Type of oil preservation system.
The number of tappings and the range of variation of the transformer ratio may be expressed in short notation by the deviations of the tapping factor percentages from the value for definitions 6076-1 terms, see 3.
If thetransformer is specifiedwithalternativemethods of cooling, the respective lower powervalues are to be stated together withtheratedpower whichrefers to the most efficient kec. The temperature-rise limits are valid for all tappings, at the appropriate tapping power, tapping voltage and tapping current.
Wheneverpercentagevalues are given it is advisablethat the corresponding reference power and reference voltage values be explicitly indicated. NOTE This way of shortnotation is only a description of the arrangement of thetappedwindinganddoesnot imply actual variations of applied voltage on that winding in service.
In addition to the main rating plate with the information listed above, the transformer shall also carry plateswithidentificationandcharacteristics of auxiliary equipment according to standards for such components bushings, tap-changers, current transformers, special cooling equipment.
Windingresistance and windingtemperatureshall bemeasured at thesametime. 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.
Such agreement is to be made between the manufacturer and the purchaser.