| 摘要 |
Electrical apparatus includes an outer enclosure, an electrode within the enclosure, and an insulating gas electrically insulating the electrode from the enclosure. A support plate is secured to the outer enclosure, and the support plate has an opening therein. A housing, containing valve means, is secured to the support plate adjacent the support plate opening. An end plate is secured to the end of the housing. The valve means in the housing are capable of being in two positions, a first position preventing the flow of gas past said valve means, and a second position wherein an opening which is through the valve means is aligned with the support plate opening. An opening is formed through the enclosure in the wall portion thereof which is in alignment with the support plate opening. The opening through the enclosure is formed without generating contamination particles within the enclosure and in a manner which minimizes escape of gas from the enclosure. Specifically, a pulling rod is welded to the outer wall of the enclosure, the support plate and valve means are secured to the enclosure with the pulling rod extending therethrough, a hollow tube having cutting means at the end thereof is positioned around the pulling rod, the cutting means is operated to effect only a partial cutting of the enclosure wall, and then a force is applied to the pulling rod to break out the portion of the enclosure wall partially cut by the cutting means. Thereafter, the pulling rod and cutting means are removed and the valve means is closed.
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