文章主要阐述了中性线的工况和各种不同接地系统中四极开关的应用及应用中需要注意的问题。

The paper mainly gives the work condition of neutral current, introduces application of four-pole switch in different grounding systems and problems to be noticed.

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极涡是该区域四季存在、冬强夏弱、向上延伸至平流层下部的基本环流系统。

Polar vortex is a basic circulation system which exists in every season (strong in winter and weak in summer) and can extend to the lower level of stratosphere.

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该系统的通用性强，性能价格比高，原则上可与各种国内外生产的四极质谱计联用，也可以脱机作为普通微机用。

The generality is high. In principle, it can be used to combine with the quadrupole mass spectrometer made at home and abroad, and as general microcomputer itself.

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