单项选择题
To （） , the power is supplied by main switchboard directly not though sub-board.
A.save network cost B.improve the reliability of supplying power to important load C.prevent sequence reverse D.increase the power factor of important load
单项选择题 （）is not installed on the main switchboard.
单项选择题 （）is used to control, modulate, monitor and protect generator set.
单项选择题 （）is not a part of the main switchboard.
