The main electrical connection is very important for the design of substations. Several special problems are analyzed and discussed in designing the 3/2 breakers connection and high voltage shunt reactor circuits. These problems include the installation of disconnectors when two complete serials are formed, the retaining of key transmission channels when two buses are cut in the 3/2 breakers connection, and the disconnector and grounding switches in high voltage shunt reactor circuits. Some suggestions with certain reference value for substation designers are proposed.