单项选择题

三相异步电动机反接制动可能发生在如下场合：。

A．锚机抛锚
B．起货机上吊货物
C．电动机停车时在定子绕组三个出线端中任选二个接在蓄电池的正负极
D．三相异步电动机反转时改变电源的相序

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