8、为什么接地开关置接地位(负端)时，主电路高电位DJ动作，而低电位DJ却不能动作?
["\u7b54\uff1aDJ\u7f6e\u63a5\u5730\u4f4d\u65f6\uff0cDJ\u7684\u4e00\u7aef\u5df2\u4e0d\u548c\u4e09\u76f8\u7ed5\u7ec4\u7684\u4e2d\u70b90\u8054\u63a5\uff0c\u800c\u662f\u4e0e\u5171\u9633\u6781\u5143\u4ef6\u8054\u63a5\uff0cDJ\u80fd\u5426\u52a8\u4f5c\uff0c\u5b8c\u5168\u53d6\u51b3\u4e8eDJ\u7ebf\u5708\u4e24\u7aef\u7535\u4f4d\u5dee\u662f\u5426\u8db3\u591f\u5927\u3002\u5f53\u9ad8\u7535\u4f4d\u63a5\u5730\u65f6\uff0cDJ\u4e24\u7aef\u7684\u7535\u4f4d\u5dee\u8db3\u591f\u5927\uff0c\u6240\u4ee5DJ\u80fd\u52a8\u4f5c\uff1a\u800c\u4f4e\u7535\u4f4d\u65f6\uff0c\u4e24\u7aef\u8fd1\u4f3c\u7b49\u7535\u4f4d\uff0c\u6240\u4ee5DJ\u4e0d\u52a8\u4f5c\u3002"]