NOVEL GRADIENT PERMITTIVITY METHOD FOR GAS INSULATED SWITCHGEAR SPACER DESIGN

• Main Author: Rizal Fabio, Muhammad
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/70682
• Institution: Institut Teknologi Bandung

Achieving a perfect functionally gradient material for gas insulated switchgear spacer has been in the minds of many engineers and scientists alike. For it could potentially reduce the footprint of spacer size due to better electric field distribution both inside and on the surface of spacer. However, it is very difficult to consistently achieve perfect gradient during spacer fabrication. This paper proposes a discrete gradient technique as a compromise to perfect gradient to improve electric field distribution. 5 layers of material with different permittivity will be stacked together to create a discrete permittivity gradient. Electric field simulation shows that discrete gradient material method shows a significant improvement compared to the design with more traditional design with uniform permittivity. Comparing this method to a perfect permittivity grading with same spacer design shows a close to similar characteristics in electric field distribution. The advantage of this method is the simplicity of the fabrication, making gradient material in insulation technology more feasible to be realized and with more consistent results. Testing this method on disk type spacer and cone type spacer results in similar reduction in maximum electric field that occurs inside the spacer and on the surface of the spacer by around 25% and overall relaxation of electric field intensity in both designs. Next, the interface between layer is modified to improve the mechanical strength of the spacer. 3 interface variants, fish scale, rounded, and sharpened is tested to see how electric field will be distributed in the spacer. Simulation suggest that changing the interface layer caused minor changes to electric field within 3% deviation. From this finding, 3 phase model is developed using FGM. Similar to its 1 phase counterparts a 25% reduction in maximum electric field and overall relaxation could be observed. Giving additional ring of FGM in the outer layer show a minimum impact to the electric field intensity. Final iteration to the design is the implementation of bigger notches for the conductor insert. Oversizing the conductor notches, despite reducing the maximum electric field both inside spacer and on the triple junction area, will overall increase the electric field intensity. 12mm modifications is deemed to be the most optimal, and capable of reducing the electric field of up to 36% in the triple junction and 29% inside the spacer.