Find the most up-to-date version of IEC at Engineering INTERNATIONAL STANDARD IEC Fifth edition Insulated bushings for alternating voltages above 1 V This English-language version is . Insulated bushings for alternating voltages above 1 V. Reference number. IEC (E). INTERNATIONAL. STANDARD. IEC. Fifth edition.
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The skin effect may be determined ice considering a depth of penetration d of current derived from the formula given below: If a flashover occurs, the test shall be repeated once only. The values of the applicable withstand test voltages for newly manufactured bushings are indicated in Tables 7, 8 and 9.
Please assess the standard in the following categories, using the numbers: All high-voltage tests, in accordance with 8. IEC iev closely with the International Organization for Standardization ISO in accordance with conditions determined by agreement between the two organizations.
INTERNATIONAL STANDARD IEC 60137
For capacitance graded bushings it is assumed that a puncture has occurred if the capacitance measured after the test raises above the capacitance previously measured by about the amount attributable to the capacitance of one layer. For bushing terminals and connections, the temperature rises are also given in Table 2.
Normally, GIS and transformer bushings are tested in the vertical position, with the flange earthed or held near to earth potential. Moisture condensation on the surface of the indoor part of the bushing is to be prevented, if necessary by ventilation or heating. For bushings of U m equal to or less than kV, markings indicated g are sufficient. An example of a marking plate is given in Figure 3. An insulating envelope may consist of one insulator unit or two or 660137 permanently assembled insulator 3.
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One method is to wrap a resistive insulated wire around a conductor dummy and to feed it by a suitable supply. Special consideration may be necessary for bushings, one or both ends of which are intended to be immersed in a gaseous medium. If a vertical bushing is to be tested horizontally, then the test load can be reduced in the same manner. Tests — Test Q: For undated references, the latest edition of the referenced document including any amendments applies.
Dielectric and thermal tests shall be carried out only on bushings complete with their fixing flanges or other fixing devices, and all accessories with which they will be fitted when in use, but without protective arcing gaps, if any.
This change is in line with other equipment standards. The bushing shall be considered to have passed the test if there is no visual evidence of damage and if it has withstood a repetition of all routine tests without significant change from the previous results.
For bushing with internal bellows, the pressure shall be stated by the supplier. The test shall be a type test only in the case of bushings with gaskets of which idc final placing is not carried out by the supplier, for example the top cap gasket of draw-through conductor transformer bushings. For wall bushings the test load shall be applied to each end of the bushing separately.
For transformer bushings, t th shall be 2 s, unless otherwise stated, with reference to IEC A bushing is normally tested in an arrangement having sufficient clearance to iev earthed parts to avoid direct flashover to them through the ambient air or the immersion medium.
The bushings shall not be damaged by the tolerated flashover in air when tested in accordance with 8. The end for immersion shall be mounted in a tank as for normal operation at ambient temperature. The tank shall be ie filled with an appropriate liquid. This fifth edition cancels and replaces the fourth edition, published inand constitutes a technical revision.
INTERNATIONAL STANDARD IEC
The temperature of the oil or gas shall be measured by means of thermometers placed at a distance of 30 cm from the bushing and, in the case of oil, 3 cm below the surface of the oil. Partial 6137 measurements before dielectric tests may be requested for information purpose only, and are not subject to guarantee. For transformer bushings, reference shall be made to 4. If the frequency at the test differs from the rated frequency, the current may be adjusted to achieve equivalent losses.
The test can, however, be omitted if it can be demonstrated, based on the results of comparative tests or calculations, that the thermal stability of the bushing is assured.
The wet test iex applicable to outdoor bushings, according to 3. It is advisable to carry out a preliminary tightness test on such components as is considered useful. Temperature limits and temperature rise The oec limits of metal parts in contact with insulating material under normal operating conditions, are as follows: Voltage records shall be made 60173 each impulse.
For examples of marking plates, see Figures 1 and 2. In such a case, the operating current and cross-section should conform with the requirements of 8. The gas shall be maintained at a temperature agreed upon between purchaser and supplier.