The longest Chinese-developed DC (direct current) submarine power line finished construction in Zhoushan, Zhejiang, on Feb 28, 2014. The line, which stretches 51 kilometers and carries the top DC voltage of 200 kilovolt, was completed on Feb 28 after seven days of construction under the sea. It will be followed by another three sections and eight lines will be laid in total.The whole project is expected to be finished by April this year and operations will start in June.