On the basis of working experience, some vital problems concerning several mounting methods, merits and faults and the process of AC electromagnetic core of short circuit ring are mentioned.

作者根据自己工作经验，提出了交流电磁铁芯短路环的几种安装方式优缺点及工艺上应注意的问题。

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The Earth's core is important because it generates the planet's electromagnetic field - which seems to be weakening.

BBC: Planet Earth