No abstract

This paper introduces a new distribution-class arrester design concept. Replacing the conventional gasketdesign concept. Replacing the conventional gasket-sealed porsealed porcelain housing is an epoxy/tiberglass-wrapped MOV celain housing is an epoxy/fiberglass-wraPPed disc disc module assembled inside a flexible EPM rubber housing.module assembled inside a flexibile EPM rubber housing. The This PDV (polymer distribution varistor) arrester design has the PDV advantage of minimizing the free-gas volume inside the arrester, volume inside the arrester, virtually eliminating concerns of virtually eliminating concerns of moisture ingress due to seal moisture ingress due to seal pumping. In addition, in the pumping.addition, in the unlikely event of arrester failure, unlikely event of arrester failure, the rubber-enclosed housing fragments normally associated with standard distribution-class with standard distribution-c1ass arrester arrester designs. The paper addresses performance questionsThe fault current withstand capability of the larger disrelated to assembling distribution arresters inside housings tribution arrester ratings can be designed equivalent to that of molded from polymer material. polymer has been utilized lower ratings. This is the result of a modular construction primarily as an alternate to porcelain in transmission and technique utilized in assembling larger PDV ratings. As an distribution insulator designs.illustration, a 27-kV rated arrester can be constructed by connecting three 9-kV modules in series. The fault current INTRODUCTION performance of the full-size 27-kV rated arresters will be as good as that of its longest individual (9-kV rated) component. The This paper introduces a new concept of distribution-classSame design philosophy has been used for years on higher surge arrester design. Historically, distribution-class arresters voltage station and intermediate-class arrester designs. have been used for the protection of distribution system equipIn contrast, standard porcelain-enclosed distribution arment, primarily transformers. Traditional design concepts insert resters, including the recently introduced nonfragmenting the arrester components, including silicon carbide blocks with designs, utilize shgle-piee designs. The larger the series gap Or more gapiess disc arrester rating, the longer the porcelain housing. Associated with elements, inside sealed porcelain housings. The internal arrester the longer housings in a decrease in fault current withstand components are protected from e n v h " t a l exposure, capability. AS such, the higher voltage porcelain-enclosed primarily moisture, by rubber-gasketed end seals. As noted by designs will have lower fault current handling capabilities than Lat and Kortschinski (I), distribution arrester seal designs have, claimed for lower voltage, shorter With the proliferation of at times, been found to be unreliable, to the extent that moisture higher voltage distribution systems and increasing short-circuit ingress problems have been noted as the...

This paper examines performance characteristics of existing distribution class arrester ground lead disconnecting devices. The paper also introduces a new Distribution Class ground lead disconnector design that not only extends the claimable detonation range well below the 20 amps specified in industry standards, but is very durable when exposed to severe arrester durability tests.Finally, this paper shows how this next generation disconnector interacts with the connected arrester to improve the overvoltage withstand capability of the arrester assembly.

The mercury transport and loss mechanisms in the metal oxide coatings of mercury low pressure discharge fluorescent lamps have been investigated. An existing model based on a ballistic process is discussed in the context of experimental mercury loss data. Two different approaches to the modeling of the mercury loss have been developed. The first one is based on mercury transition rates between the plasma, the coating, and the glass without specifying the underlying physical processes. The second one is based on a transport process driven by diffusion and a binding process of mercury reacting to mercury oxide inside the layers. Moreover, we extended the diffusion based model to handle multi-component coatings. All approaches are applied to describe mercury loss experiments under the influence of an Al2O3 coating.

No abstract