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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On-line information is also available on recently issued publications, withdrawn and replaced publications, as well as corrigenda. The measurement shall not be made at a voltage exceeding the dry power-frequency withstand voltage.
NOTE 2 This tap can also be used for the measurement of dissipation factor, capacitance and partial discharge. Definitions, principles and rules IEC If artificial pollution tests are required, they shall be performed in accordance with IEC A bushing is normally tested in an arrangement having sufficient clearance to surrounding earthed parts to avoid direct flashover to them through the ambient air or the immersion medium.
INTERNATIONAL STANDARD IEC 60137
NOTE 4 For bushings where upper and lower insulating envelopes are assembled by clamping force on the central fixing conductor, it is recommended to choose the cantilever test load, taking into account the thermal expansion of the conductor due to the rated current flow.
Partly or completely immersed bushings, according to 3. IEC shall not be held responsible for identifying any or all such patent rights. The ambient air temperature shall be measured with lagged thermometers placed around the bushing at mid-height and at a distance of 1 m to 2 m from it.
Power transformers and reactors IEC For gas-immersed bushings, the tank shall be filled with gas at maximum operating pressure at ambient temperature.
Limiting values for temperature rise and dielectric dissipation factor have therefore been introduced. The bushing has reached thermal stability ie its dielectric dissipation factor shows no appreciable rising tendency, with respect to the ambient temperature, for a period of 5 h.
Voltage records shall be made of each impulse. The actual temperature during the measurement shall be stated in the test report. For bushings with 6013 r equal to or greater than 4 A, I th shall always be kA. If the calculated temperature exceeds this limit, the ability of the bushing to withstand the standard value of I th shall be demonstrated by a test. At the request of the purchaser, the supplier shall furnish any information concerning the minimum clearances to earthed parts in the operating arrangement.
A IEC Figure 3 — Marking plate for bushings for highest voltage for equipment equal to or less than 52 kV made of ceramic, glass or inorganic materials, resin or combined insulation see 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.
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The insulating envelope shall be equipped with its fixing devices and fittings, preferably as in the intended application, and with additional plates with valve and pressure gauge for the test. If during the repetition of the test no iev or puncture occurs, the bushing shall be considered to have passed the test. Generation, transmission and distribution of electricity — Operation IEC 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.
Repetition of a type test is only mandatory when specified in a particular contract. The wet test is applicable to all outdoor bushings according to 3. Table 10 — Applicability of type tests see 7. For bushings operating in air-insulated ducting, locally high ambient air temperatures have a significant effect on their current rating.
Liquid-containing bushings shall remain empty and shall have an opening for free gas circulation within the envelope. NOTE 1 The daily mean temperature of the immersion medium should be calculated by averaging 24 consecutive hourly readings. Bushings used as isc integral part of apparatus, such as switchgear or transformers, shall meet the thermal requirements for the relevant apparatus.
Owing to the limitations of puncture strength and flashover voltage in the immersion medium, it may not always be possible to check the adequacy of the increased arcing distance by actual tests at any altitude lower than that of operation.
Any divergence between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter. Dry power-frequency withstand test voltage levels for transformers bushings should be increased according to 9.
During the test, the dielectric dissipation factor shall be measured frequently and the ambient air temperature shall be recorded at each measurement.
Their preparation is entrusted to technical committees; any IEC 6137 Committee interested in the subject dealt with may participate in this preparatory work. Gas-insulated and gas-impregnated bushings have become a mature technology, for use in gas insulated switchgear. 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.
NOTE Capacitance and dielectric dissipation factor measurements made on site may differ from factory iex given on the nameplate.
NOTE For 6013 in contact with metallic parts, special attention should be paid to the ability of the material to withstand the temperature rise.
To simulate service conditions, the bushing shall be mounted on an earthed plane, radially extended from the axis of the bushing at least 0,4 L in every direction, L being the dry ieec distance of the bushing. It is advisable to carry out a preliminary tightness test on components for which the test is considered useful.
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.