BS EN 62271-209:2007 – High-voltage switchgear and controlgear — Part 209: Cable connections for gas-insulated metal-enclosed switchgear for rated voltages above 52 kV — Fluid-filled and extruded insulation cables — Fluid-filled and dry-type cable- terminations

5.3 Rated insulation level The rated insulation level for the cable connection assembly shall be selected from the values given in IEC 60038 (IEC standard voltages) as well as IEC 62271 -203:2003.
5.4 Rated normal current and temperature rise The connection interface of the main circuit shown in Figures 2 and 3 for fluid-filled cable- terminations and Figures 4 and 5 for dry-type cable-terminations is applicable at rated normal currents up to 3 1 50 A.
The normal current-carrying contact surfaces of the connection interface shall be silver- or copper-coated or solid copper. For full interchangeability of the cable-termination, the connection interface shall be designed so that at a current equal to the cable rated current corresponding to a maximum temperature of 90 °C, no heat transfer from the GIS main circuit end terminal to the cable-termination will occur.
NOTE As the maximum conductor temperature for cables is limited by the maximum operating temperature for the insulation, there are certain cable dielectrics which cannot withstand the maximum temperature specified for gas- insulated metal-enclosed switchgear if there is heat transfer across the connection interface to the cable terminations. For cases when the design value of 90 °C at rated normal current of the cable system cannot be achieved, the manufacturer of the switchgear should provide the necessary data on temperature rise of the main-circuit end terminal and of the insulating gas (SF 6 ) as a function of current.
5.5 Rated short-time and peak withstand currents and rated duration of short circuit Short-time and peak withstand currents as well as the duration of short circuit shall refer to the levels provided by the cable system, not exceeding the values given in IEC 60694.
5.6 Rated filling pressure of insulating gas in the cable connection enclosure If SF 6 is used as the insulating gas, the minimum functional pressure for insulation p me used to determine the design of the cable-termination insulation shall not exceed p me = 0,35 MPa (absolute) at 20 °C for maximum rated voltages up to 300 kV. For maximum rated voltages exceeding 300 kV the minimum functional pressure for insulation p me used to determine the design of the cable-termination insulation shall not exceed p me 0,4 MPa (absolute) at 20 °C.
The rated filling pressure p re of gas for insulating is assigned by the switchgear manufacturer but shall in no case be lower than p me . If a gas other than SF 6 is used, the minimum functional pressure shall be chosen to give the same dielectric strength while being lower than the maximum recommended operating pressure as per 6.1 .
BS EN 62271-209:2007 – High-voltage switchgear and controlgear — Part 209: Cable connections for gas-insulated metal-enclosed switchgear for rated voltages above 52 kV — Fluid-filled and extruded insulation cables — Fluid-filled and dry-type cable- terminations