3.2　Main Electrical Connection

3.2.1　The main electrical connection of a substation shall be determined based on the role of the substation in the grid，the number of outgoings，equipment features and load characteristics，and shall ensure reliable power supply，flexible operation，easy operating and repairing，low cost and convenient extension.

The voltage levels should be reduced and the connection be simplified provided that the power supply plan can be satisfied.

3.2.2　A minimum number of circuit breakers or even no circuit breaker shall be used on the high voltage side of a substation provided that the operational requirements can be met.

3.2.3　For 35kV-110kV lines，bridge connection，enlarged bridge connection，line-transformer unit connection or T-shape connection，single busbar or sectionalized single busbar connection should be used.

3.2.4　Where there are eight or more 35kV-66kV outgoings，double busbar connection should be used.If there are six or more 110kV outgoings，double busbar connection should be used.

3.2.5　Where there are two or more main transformers in a substation，sectionalized single busbar connection should be used for 6kV-10kV lines.The busbar shall be sectionalized in a way to facilitate load distribution among the remaining main transformers when one main transformer is out of service.

3.2.6　Where it is necessary to limit the short-circuit current of the 6kV-10kV lines，one of the following measures may be taken:

1　Separate operation of transformers；

2　High-impedance transformers；

3　Series current-limiting devices in the transformer loop.

3.2.7　The lightning arrester and potential transformer connected to a busbar may share one set of disconnector.The lightning arrester connected to transformer should not be equipped with disconnector.