Zhoushan DC Transmission Project is the first industrial test project in China where Zhoushan Power Grid and Mainland Power Grid are connected by submarine cable; its ultimate capacity is ?100kv，500a,100mw while the ultimate capacity of the last phase project was -100kv 500a，50mw. All the new equipments are developed by Xi'an Electric Manufacturing Complex while the project is constructed by Electric Power Bureau of Zhejiang Province.
The transmission distance is: DC overhead line 42.1km, submarine cable 12km, totally 54.1km; power is supplied from rectifier station at Dagan Town, Ningbo City of Zhejiang Province to inverter station at Aotoupu of Dinghai County, Zhoushan Island. The project was started design in 1980 and was put into operation in Dec., 1987; its construction lasted 8 years. We can see from this the weakness of domestic DC technology at that time and the difficulties in work. But the project is the beginning of domestic DC technology being used in a project. After the project has operated 10 years, Xi'an High Voltage Apparatus Research Institute, at the request of Electric Power Bureau of Zhejiang Province, has checked and calculated the design and equipments of the project by using the imported technologies of Gezhouba — Shanghai Project in 1997. The control and protective system were changed into microcomputer controlled system in 1998, thus it realized the function of power reversal.
The following complete set of new equipments made by Xi'an Electric Manufacturing Complex are used in the project:
1. Thyristor valve
2. Converter transformer
3. Smoothing reactor
4. Alternating current filter
5. Lightning arrester
6. Numerical controlled adjustment device（manufactured by Shanghai Relay Factory）
7. DC voltage transformer
8. DC current transformer
9. Protective relaying device（manufactured by Shanghai Relay Factory）
10. DC submarine cable（manufactured by Hongqi Cable Works）
The project was rewarded with special award of Progress Prize in Science and Technology issued by Ministry of Machine-building and Electronics Industry in 1990; with a second prize of National Prize for Progress in Science and Technology in 1992.