主断路器的功用是什么？
["\u4e3b\u65ad\u8def\u5668\u662f\u7535\u529b\u673a\u8f66\u7684\u603b\u5f00\u5173\u548c\u603b\u4fdd\u62a4\u3002\u5b83\u8d77\u4e24\u79cd\u4f5c\u7528\uff1a\uff081\uff09\u63a7\u5236\u4f5c\u7528\uff1a\u6839\u636e\u673a\u8f66\u8fd0\u884c\u7684\u9700\u8981\uff0c\u5c06\u4ea4\u6d41\u9ad8\u538b\u7535\u5f15\u5165\u673a\u8f66\u6216\u65ad\u5f00\uff1b\uff082\uff09\u4fdd\u62a4\u4f5c\u7528\uff1a\u5f53\u673a\u8f66\u53d1\u751f\u6545\u969c\u65f6\u5feb\u901f\u5207\u9664\u4ea4\u6d41\u9ad8\u538b\u7535\u6e90\uff0c\u4f7f\u6545\u969c\u8303\u56f4\u5c3d\u91cf\u7f29\u5c0f\u3002"]