Figure 1. Geometry of a HVDC GIL Source: Authors’ own work A three-dimensional cutaway diagram identifies the main components of a gas insulated conductor assembly. The assembly contains an H V conductor extending through a grounded cylindrical enclosure. A conical spacer supports the con... More about this image found in Geometry of a HVDC GIL Source: Authors’ own work A three-dimensiona...

Figure 2. Comparison of the measurement data of the current density J → in SF ₆ from Hanna et al, (2016) with the electrical conductivity model (12) multiplied with   E → in the range [1 kV-20kV] to obtain the resulting current density J → with respect to the electric field E → Source: Authors’ own work A logarithmic line graph compares measured and modelled current density against electric field strength. The horizontal axis gives electric field strength E from 0.2 to 2.0 times 10 to the power of 7 volts per metre. The vertical axis gives current density J in amperes per square metre on a logarithmic scale. Conditions are 20 degrees Celsius, 0.6 megapascals, and 2 per cent relative humidity. The sulfur hexafluoride electric conductivity model and measurement data both increase with electric field strength. Current density rises gradually below about 0.8 times 10 to the power of 7 volts per metre, increases steeply from about 0.9 to 1.5 times 10 to the power of 7 volts per metre, then increases more slowly towards 2.0 times 10 to the power of 7 volts per metre. Measurements remain slightly above the model through most of the range and converge near the highest field strengths. More about this image found in Comparison of the measurement data of the current density J → ...

Figure 3. Comparison of the measurement data of the current density J → in SF ₆ from Zavattoni (2014) with the electrical conductivity model (12) multiplied with E → = 6   kV/mm to obtain the resulting current density J → with respect to the gas pressure P Source: Authors’ own work A logarithmic line graph compares measured and modelled current density across gas pressure values. The horizontal axis gives pressure P from about 0.1 to 1.1 megapascals. The vertical axis gives current density J from 10 to the power of negative 12 to 10 to the power of negative 10 amperes per square metre on a logarithmic scale. Conditions are 20 degrees Celsius, 6 kilovolts per millimetre, and 2 per cent relative humidity. The sulfur hexafluoride electric conductivity model increases steadily from about 8 times 10 to the power of negative 12 amperes per square metre at 0.1 megapascals to about 7 times 10 to the power of negative 11 amperes per square metre at 1.1 megapascals. Measurement values occur near 6 times 10 to the power of negative 12 at 0.1 megapascals, 5 times 10 to the power of negative 12 at 0.3 megapascals, 1.5 times 10 to the power of negative 11 at 0.5 and 0.7 megapascals, 3.5 times 10 to the power of negative 11 at 0.9 megapascals, and 5 times 10 to the power of negative 11 at 1.1 megapascals. Measurements remain below the model across the pressure range. More about this image found in Comparison of the measurement data of the current density J → ...

Figure 4. Comparison of the measurement data of the current density J → in SF ₆ from Zavattoni, (2014) with the electrical conductivity model (12) multiplied with E → (see values in the figure) to obtain the resulting current density J → with respect to the temperature T Source: Authors’ own work A logarithmic line graph compares current density against temperature at five electric field strengths. The horizontal axis gives temperature T from about 290 to 360 kelvin. The vertical axis gives current density J in amperes per square metre on a logarithmic scale. Conditions are 0.6 megapascals and 2 per cent relative humidity. Measurement series represent electric field strengths of 4, 6, 10, 16, and 18 kilovolts per millimetre. Each series contains values near 293, 313, and 353 kelvin and increases with temperature. The 4 and 6 kilovolts per millimetre series remain below 10 to the power of negative 10 amperes per square metre. The 10 kilovolts per millimetre series rises from about 4 times 10 to the power of negative 11 to about 2 times 10 to the power of negative 10 amperes per square metre. The 16 and 18 kilovolts per millimetre series remain several orders of magnitude higher and increase from approximately 10 to the power of negative 8 towards several times 10 to the power of negative 8 amperes per square metre. More about this image found in Comparison of the measurement data of the current density J → ...

Figure 5. Comparison of the measurement data of the current density J → in SF ₆ from Zavattoni, (2014) with the electrical conductivity model (12) multiplied with E → =   6 kV/mm to obtain the resulting current density J → with respect to the gas humidity content RH3D Geometry Model of the HVDC GIL Source: Authors’ own work A logarithmic line graph compares measured and modelled current density across relative humidity values. The horizontal axis gives relative humidity R H from 0 to 35 per cent. The vertical axis gives current density J from 10 to the power of negative 11 to 10 to the power of negative 9 amperes per square metre on a logarithmic scale. Conditions are 20 degrees Celsius, 6 kilovolts per millimetre, and 0.6 megapascals. The sulfur hexafluoride electric conductivity model increases steadily from about 2 times 10 to the power of negative 11 amperes per square metre at 0 per cent relative humidity to about 5 times 10 to the power of negative 10 amperes per square metre at 35 per cent. Measurement values generally increase from approximately 3 to 4 times 10 to the power of negative 11 amperes per square metre below 6 per cent to values between about 1 and 5 times 10 to the power of negative 10 amperes per square metre above 20 per cent. Individual measurements vary around the model, with lower values near 12 and 27 per cent and higher values near 22, 26, and 31 per cent. More about this image found in Comparison of the measurement data of the current density J → ...

Figure 6. 3D geometry model of the HVDC GIL Source: Authors’ own work A three-dimensional model defines the geometry, boundary conditions, and material properties of a gas insulated system. The model consists of a cylindrical enclosure with a central high voltage conductor passing through... More about this image found in 3D geometry model of the HVDC GIL Source: Authors’ own work A three...

Figure 7. Electric field distribution in the HVDC GIL model assuming a constant electrical conductivity of the SF ₆ gas Source: Authors’ own work An electric field map shows field distribution for sulfur hexafluoride conductivity of 1 times 10 to the power of negative 18 siemens per metre. The map shows the conductor passing through a conical spacer inside a cylindrical enclosure. The maximum electric field is 4.03 kilovolts per millimetre. The electric field scale ranges from 0 to 2.5 kilovolts per millimetre. Higher field intensity occurs along the conductor surface and around the junction between the conductor and spacer. Lower field intensity occupies most of the spacer and surrounding sulfur hexafluoride region. More about this image found in Electric field distribution in the HVDC GIL model assuming a constant ele...

Figure 8. Electric field distribution in the HVDC GIL model with the application of (12) in the gaseous domain (left: gas humidity content RH = 2%, right: gas humidity content RH = 30%) Source: Authors’ own work Two electric field maps compare field distribution at 2 per cent and 30 per cent relative humidity. The left panel corresponds to 2 per cent relative humidity and records a maximum electric field of 3.88 kilovolts per millimetre. The right panel corresponds to 30 per cent relative humidity and records a maximum electric field of 2.51 kilovolts per millimetre. Both panels show the conductor passing through a conical spacer inside a cylindrical enclosure. The electric field scale ranges from 0 to 2.5 kilovolts per millimetre. Higher field intensity concentrates along the conductor surface and near the spacer junction, while lower field intensity occupies the surrounding sulfur hexafluoride region. More about this image found in Electric field distribution in the HVDC GIL model with the application of...

Figure 9. Flow velocity of the SF ₆ gas in a horizontally and vertically arranged HVDC GIL Source: Authors’ own work Two flow velocity maps compare horizontal and vertical gas flow around a conductor and conical spacer. The upper panel presents the horizontal configuration and the lower panel presents the vertical configuration. Each panel shows a circular cross section of the conductor, spacer, and enclosure together with a corresponding three-dimensional view. The flow velocity scale ranges from 0 to 0.35 metres per second. Higher flow velocity occurs around the conductor surface and along the enclosure boundary. The horizontal configuration shows localised higher velocity regions around the conductor and outer enclosure. The vertical configuration shows a more uniform velocity distribution around the conductor with higher velocity concentrated close to the conductor surface. The x, y, and z axes indicate the orientation. More about this image found in Flow velocity of the SF ₆ gas in a horizontally and vertically ...

Figure 10. Temperature distribution with the consideration of heat convection and heat radiation in the SF ₆ gas in a horizontally and vertically arranged HVDC GIL Source: Authors’ own work Two temperature maps and two device views compare horizontal and vertical conductor configurations. The horizontal temperature map has a circular conductor cross section with temperature concentrated near the conductor and extending asymmetrically through the surrounding gas. The vertical temperature map has a circular conductor cross section with temperature distributed more evenly around the conductor. The temperature scale ranges from 290 kelvin to 330 kelvin at intervals of 5 kelvin. The x, y, and z axes indicate orientation. Two accompanying cutaway views depict the conductor and conical spacer inside the cylindrical enclosure in horizontal and vertical arrangements. More about this image found in Temperature distribution with the consideration of heat convection and heat...

Figure 11. Electric field distribution for SF ₆ gas with a 2% relative humidity content, including heat convection and thermal radiation in a horizontally and vertically arranged HVDC GIL Source: Authors’ own work Two electric field maps compare horizontal and vertical configurations at 2 per cent relative humidity. The horizontal configuration records a maximum electric field of 2.89 kilovolts per millimetre. The vertical configuration records a maximum electric field of 2.34 kilovolts per millimetre. Both maps depict the conductor passing through the conical spacer inside the cylindrical enclosure. Electric field intensity concentrates along the conductor and near the junction between the conductor and spacer. The electric field scale ranges from 0 to 2.5 kilovolts per millimetre at intervals of 0.5 kilovolts per millimetre. More about this image found in Electric field distribution for SF ₆ gas with a 2% relative hum...

Figure 12. Electric field distribution for SF ₆ gas with a 30% relative humidity content, including heat convection and thermal radiation in a horizontally and vertically arranged HVDC GIL Source: Authors’ own work Two electric field maps compare horizontal and vertical configurations at 30 per cent relative humidity. The horizontal configuration records a maximum electric field of 2.13 kilovolts per millimetre. The vertical configuration records a maximum electric field of 1.83 kilovolts per millimetre. Both maps depict the conductor passing through the conical spacer inside the cylindrical enclosure. Electric field intensity concentrates along the conductor and near the junction between the conductor and spacer. The electric field scale ranges from 0 to 2.5 kilovolts per millimetre at intervals of 0.5 kilovolts per millimetre. More about this image found in Electric field distribution for SF ₆ gas with a 30% relative hu...

Figure 1. Three-dimensional view of the Braking system using Permanent Magnets A diagram of a cylindrical aluminium armature with permanent magnets arranged around an iron yoke inside a cubic enclosure. The diagram presents a cylindrical aluminium armature positioned inside a transparent cubic... More about this image found in Three-dimensional view of the Braking system using Permanent Magnets A d...

Figure 2. Axial-Flux Permanent Magnet Braking System Prototype: (a) Aluminum Conductive Disk, (b) Inductor with Circular Permanent Magnets A 2-panel photograph presents a mounted aluminium disc in a and a circular plate with 8 permanent magnets in b. The 2-panel photograph presents components ... More about this image found in Axial-Flux Permanent Magnet Braking System Prototype: (a) Aluminum Conducti...

Figure 3. 2D geometric model in the plane (r- θ ) A diagram of 8 permanent magnets labelled N and S around a circular plate, with dimensions R 1, R 2, R 3, and R p. The diagram presents 8 circular permanent magnets arranged around a circular plate, with 4 labelled N and 4 labelled S in an alternating pattern. Horizontal and vertical axes intersect at the plate centre. R 1 extends diagonally from the centre to the plate edge. R 2 extends vertically from the centre towards a lower magnet position. R 3 marks the horizontal spacing between 2 upper magnets, and R p marks the diameter of the upper-left magnet. More about this image found in 2D geometric model in the plane (r- θ ) A diagram ...

Figure 4. B(H) curve of the back-irons (carbon steel) used in 3D FEA A line graph plots magnetic flux density B against magnetic field strength H, rising rapidly before levelling near 2 teslas. The line graph plots magnetic flux density B in teslas against magnetic field strength H in ampere... More about this image found in B(H) curve of the back-irons (carbon steel) used in 3D FEA A line grap...

Figure 5. 3D FEM Magnetic geometric Model of the axial-flux permanent magnet braking system (Meshes 331 120 tetrahedral elements) A three-dimensional mesh diagram of a cylindrical assembly within a cubical domain, with x, y, and z axes. The three-dimensional mesh diagram presents a cylindric... More about this image found in 3D FEM Magnetic geometric Model of the axial-flux permanent magnet brakin...