single needle lockstitch machine

The through simply analyzing and comparing,the effect of conducting lightning and protected zone of the furcated lightning rod and the single lightning rod have shown that furcating of lightning rod is not is not necessary.

　对分叉避雷针与单针的引雷效果和保护范围进行简单的分析对比,由此来说明避雷针分叉没有必要。