| 摘要 |
The varistor unit provides overvoltage protection, e.g. for power station instrumentation. Between two conductive cylindrical mountings (5, 6) there are one or more metal oxide-based varistors, in a cylindrical active section (8). The mountings seal against the ends of a cylindrical insulating casing (1), with an insulating filling around the active section. The casing is completed by an insulating tube (2) which is injection moulded or extruded. This has a surrounding, screened weather proofing (3). One mounting (5) is moulded into an end of the tube (2). The other, having an external thread (15), is screwed into an internal thread at the other end of the tube. This provides compressive contact force. Preferably the tube is a fibre-reinforced thermoplastic polymer, especially a polyamide with up to 50 wt.% glass fibre. |
