The selection of Bundle configuration is commonly based on techno-economic optimization while ensuring a satisfactory - though not optimum- corona/RI performance. This leaves a margin for improving their corona/RI performance, while passing through any corona/RI sensitive areas along the line route, just by changing their intra-group (IG) spacing. The presently used 45 cm IG spacing on Twin-Moose Bundle conductor for Indian 400 kV lines is based on techno-economic choice but not corona optimal and could be reduced to 16–17cm to achieve corona optimality though the improvement in corona/RI performance of the Bundle through this reduction is only around 3.5%. This may be too small for practical use but does suggest a smaller IG spacing. There is therefore an urgent need to review the present Bundle configuration is in the context of completely changed technoe-conomic scenario.
