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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S dry-type transformer a transformer of which the magnetic circuit and windings are not immersed in an insulating liquid [IEV 3. Installation environment An environment with a pollution rate see IEC and IEC that does not require special consideration regarding the external insulation of transformer bushings or of the transformer itself.
Open windingsin a three-phase transformer that are not connectedtogether in the transformer but have both ends of each phase winding brought out to terminals are indicated as III HVor iii 60076–1 or low-voltage windings. CFVV applies for tappings with tapping factors below the maximum voltage tapping factor.
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 loading. The loading combinations should also be indicated unless the rated power of one of the windings is the sum of the rated powers of the other windings.
NOTE On multi-winding transformers, supplementary information will generally be required. For a three- phasetransformer the impedance is expressed as phase impedance equivalent star connection. Wherea tolerance in one direction is omitted, there is no restriction on the value in that direction. NOTE This numbering is arbitrary. Index 2 Indicates conditions during measurement of load loss In measuring the cold resistance for the purpose of temperature-rise determination, special efforts shallbe made to determinetheaveragewindingtemperatureaccurately.
Standard categories of tapping voltage variation. For selection of tapping for the test, see 5. Atransformerwithatapped kV windinghavingaltogether21tappings, symmetrically placed, is designated: Rated voltage for each winding. The quantity ‘highest voltage for equipment’ which characterizes the insulation of the winding, is also kV see IEC Thetransformershallbecapable of carrying, in continuous service, the rated power for a multi-windingtransformer: Therequirements of this clause should be used as far as applicable.
In addition the short-circuit impedance values for the principal tapping and at least the extreme tappings shall be given, preferably in ohms per phase referred to a specific winding. When IEC standards do not exist for such categories of transformers, this part of IEC may still be applicable eitheras a whole or in part.
The connection fitted at the works shall be indicated. Theirpreparationis entrustedtotechnicalcommittees;any IEC NationalCommitteeinterested in thesubjectdealtwith may participateinthispreparatorywork.
The measurement of windingresistanceshallbemadeaccording to The neutral conductor and terminal of transformers not intended to carry load between phase and neutral shall be dimensioned for earth-fault current.
The load loss is measured with the winding at an average temperature 8. The apparent power that the transformer delivers to the circuit connected to the terminals of the secondary winding under rated loading differs from the rated power. In the absence of such specification, guidance on loading of transformers complying with this part may be found in IEC and in IEC Log In Sign Up. Terminal marking on the transformer follows national practice. U,I, Tappingvoltageandtappingcurrentintheuntappedwinding.
Auto-transformers with a neutral terminal intended to be permanently connected to earth shall be treatedasnormaltransformerswith two star-connected windings.
IEC 1 Power transformers General. If the cooling system is OF or OD, the pump may be used to mix the oil. The other winding is an energizing winding [IEVmodified] 3.
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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. Other tappings are identified by their tapping factors. The transformer shall be approximately at factory ambient temperature.
Such measurements may be less representative of losses in service.
For a multi-winding transformer this percentage is referred to the winding with the highest rated power. At thetime ic publication,theeditions indicated were valid. This applied voltage is referred to as the short-circuit voltage [IEV of the pair of windings.
Abscissa Tapping factor, percentage indicating relative number of effective turns in tapped winding.
If a lightning impulse voltage test is required, whether or not the test is to include chopped waves see IEC Thepolarity of single-phasetrans- formers and the connection symbol of three-phase transformers shall be checked. The winding connection letter for any intermediate and low-voltage winding is immediately followed by its phase displacement ‘clock number’ see definition 3. NOTE It is recognized that the most severeloading conditions for testvoltagesourceaccuracy are usually imposed by large single-phase transformers.
NOTE 1 Inconditions wherewindingbalancing ampere-turnsare missing,therelationbetween voltage and current is 06076-1 not linear.
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To make sure that we continue to meet your needs,your feedback is essential. Click here to sign ice. This difference is generally expressed as a percentage of the no-load voltage of the former winding. The matters should preferably beraised at an earlystage and the agreementsincluded in thecontract specification. Restrictions on dimensions and mass. It is normally expressed as a percentage.