BS IEC IEEE 65700 pdf free download

BS IEC IEEE 65700-19-03 2014 pdf free download.Bushings for DC application.
5.2 Factors affecting the design, testing and application Where particular operating conditions exist, they shall be specified by the purchaser. Examples of such conditions are as follows: a) The ambient air temperature, for bushings operating wholly or partially in the valve hall. It is common to have a maximum HVDC valve hall air temperature well over the standardised 40 °C maximum air temperature. Values up to 60 °C are of usual practice. Such high ambient air temperatures have significant effects on dielectric withstand as well as maximum operating temperature. If a valve hall air ambient temperature exceeding 40 °C is specified care should be taken regarding dielectric withstand performance as well as maximum operating temperature. b) Surface creepage distance may be achieved using shed material of porcelain, silicone rubber or other materials. Where silicone rubber is used the selection and amount of fillers may have a large impact on the useful life. The type of shed profile such as anti-fog or long-short (ratio 0,7) may improve voltage withstand conditions over even or uniform shed design c) Inclination. d) Seismic loading. e) Vibrations or shocks. f) Transportation or storage conditions. g) Other thermal conditions. h) Damaging fumes or vapours, excessively abrasive or conducting dusts, explosive mixtures of dust or gases, salt spray, icing, etc. i) Proximity of insulating barriers or earthed walls within the transformer or reactor. j) Proximity of the walls or roof of a building. k) Ice loading conditions. l) Overloads. 5.3 Altitude correction Although the insulation level refers to sea level, bushings corresponding to this standard are declared suitable for operation at any altitude not exceeding 1 000 m. In order to ensure that the external withstand voltages of the bushing are sufficient at altitudes exceeding 1 000 m, the arcing distance normally required shall be increased by a suitable amount. It is not necessary to adjust the radial thickness of insulation or the clearance of the immersed end. The puncture strength and the flashover voltage in the immersion medium of a bushing are not affected by altitude.
For installations at an altitude higher than 1 000 m, the arcing distance under the standard reference atmospheric conditions shall be determined in order to withstand the voltages obtained by multiplying the withstand voltages required at the service location by a factor k in accordance with Figure 1 .
5.4 Interchangeability DC bushings in converter transformers and smoothing reactors are not normally interchangeable with other DC bushings of the same voltage and current. This is because the condenser foil arrangement must align properly with the insulating barriers to minimise voltage stresses. This may not apply to DC bushings without insulating barriers. 6 General requirements 6.1 Electrical requirements • Voltage withstand tests • Partial discharge • Dissipation factor and capacitance • Bushing voltage tap. Capacitance graded bushings may be provided with a voltage tap. This tap is normally intended for use as a voltage divider during normal operation and may require the use of additional capacitance to limit the output voltage and protective devices. These additional components may be mounted directly to the bushing or in the transformer control cubicle. • Bushing test tap. Capacitance graded bushings may be provided with a bushing test tap. This tap is normally grounded and is intended for measurement of dissipation factor, capacitance from conductor to tap, and partial discharge. Since the capacitance from tap to ground is not controlled, the tap is not intended for use as a voltage divider during normal operation. Bushing test tap functionalities may be integrated in voltage tap. • When not in use the voltage tap and test tap shall be effectively grounded throughout the life of the bushing • Creepage distance 6.2 Mechanical requirements • Dimensions • Cantilever strength • Internal pressure and vacuum • Apparatus bushings shall be designed to withstand full vacuum when mounted in the apparatus tank • Draw lead bushing cap pressure The liquid or gas for internal insulation of the bushing shall comply with their relevant material standards: • IEC 60376 for new SF 6 or IEC 60480 for used SF 6 . • IEC 60296 for oil, or • IEC 60836 or IEC 60867 for synthetic fluid. 6.3 Nameplate markings The following information shall appear on all bushing nameplates: • Manufacturer’s name, identification number, type, year of manufacture and serial number. • Rated continuous DC voltage (for bushings for pure DC application, see 4.1 .1 ). • Rated peak voltage (for bushings for combined voltage applications, see 4.1 .2). • Rated continuous DC current, where applicable. • Rated continuous AC current, where applicable.BS IEC IEEE 65700 pdf download.