不需额外电源。
此外，新型户外电源的出现为运营商低成本快速建设网络提供了新的思路。
In addition, the emergence of outdoor power systems provides a new way for the operators to cut cost and rapidly construct networks.
在电动机里电流是由外电源供给的感生电动势的方向和电枢电流i方向相反。
Years in the motor current is outside the power supply from the induced electromotive force and the direction of armature current I in opposite directions.
应用推荐