| 摘要 |
A varistor stack (2) is arranged coaxially in a housing (1) which is constructed as a hollow cylinder, consists of porcelain and is sealed at the top and bottom by covers (7a, 7b) and flanges (8a, 8b) which consist of aluminium and are at the same time used as electrical connections. In order to simplify assembly and to secure the varistor stack (2) against mutual displacement of the individual metal-oxide varistors (3), the stack has a shrink sleeve (4) around it. The expansion space (6) is formed by central holes (5) in the metal-oxide varistors (3). A contact-pressure spring (11) is clamped in between the upper end of the varistor stack (2) and the upper cover (7a) and is surrounded by a bellows (13) which seals the expansion space (6) against the insulating compound (12) which consists of oil and quartz sand and with which the majority of the housing (1) is filled. The varistor stack (2) is constructed by the individual metal-oxide varistors (3) being threaded onto a guide rod, using the holes (5). Once the shrink sleeve (4) has subsequently been shrunk on by heating it, the guide rod is removed and the varistor stack (2) is mounted in the housing (1). <IMAGE>
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