The general connection is: The transformers are directly connected with distribution cabinets. The high-voltage sides of transformers are inlet by high-voltage cables, while the low-voltage sides of transformers are outlet by hard busbar. The distance between the transformers' copper busbar, connected with distribution cabinets and the ground should be guaranteed. As for the direction of the screws, the direction must be consistent no matter what the direction is. At the same time, the length of all screws shall also be ensured with 3-5 threads left when screws are tightened. From the perspective of beauty and generosity, upward direction looks more elegant. Upward direction is also conducive to construction, but it is not suitable for examination, while the downward direction is suitable for both examination and construction.

The key is the selection of junction line groups of distribution transformer .

There are only two kinds of sidewinding: Y and Δ. Four combinations of double loop transformer are Y/Y, Δ/Y, Y/Δ and Δ/Δ. Y/Y junction line group is a simultaneous input-output phase. There are other five different phases, 0, 2, 4, 6, 8, 10 respectively, according to clock representation. Clock representation is the phase relationship between input and output. Δ/Δ junction line group is also a simultaneous input-output phase and there are also other five different phases, 0, 2, 4, 6, 8, 10 respectively, according to clock representation. Δ/Y and Y/Δ junction line groups are asynchronous input-output phase according to clock representation. They are 1, 3, 5,7, 9, 11 respectively, the phase relationship between input and output, which needs to be described with vectogram.