Application of Special Arresters on 138 kV Lines of Application Power Company
Special zinc oxide series gapped line arresters were installed on Appalachian Power Company 138 kV lines having high tower footing resistance and severe lightning exposure. This effort was part of an experiment to explore means of reducing lightning flashovers in exposed locations where low ground resistances are not feasible. Because of possible future voltage uprating of these lines, the arresters were built in the form of high strength nonporcelain mechanical struts, designed to limit phase conductor swing. This paper describes the field installation of these experimental arresters and their instrumentation and reports operating experience in 1983.
The expulsion protective gap
THE EXPULSION protective gap consists of a fiber tube of proper bore and dimensions so arranged with an internal gap that lightning discharges are conducted within the tube and the power follow current is stopped through the expulsion action of the tube. Its action during interruption of follow current is similar to that of the expulsion fuse. In practice the expulsion gap is provided with a series gap, the whole assembly being electrically in parallel with the insulation to be protected.
Characterization and gene cloning of a maltotriose-forming exo-amylase from Kitasatospora sp. MK-1785
A maltotriose-forming amylase (G3Amy) from Kitasatospora sp. MK-1785 was successfully isolated from a soil sample by inhibiting typical extracellular α-amylases using a proteinaceous α-amylase inhibitor. G3Amy was purified from the MK-1785 culture supernatant and characterized. G3Amy produced maltotriose as the principal product from starch and was categorized as an exo-α-amylase. G3Amy could also transfer maltotriose to phenolic and alcoholic compounds. Therefore, G3Amy can be useful for not only maltotriose manufacture but also maltooligosaccharide-glycoside synthesis. Further, the G3Amy gene was cloned and expressed in Escherichia coli cells. Analysis of its deduced amino acid sequence revealed that G3Amy consisted of an N-terminal GH13 catalytic domain and two C-terminal repeat starch-binding domains belonging to CBM20. It is suggested that natural G3Amy was subjected to proteolysis at N-terminal region of the anterior CBM20 in the C-terminal region. As with natural G3Amy, recombinant G3Amy could produce and transfer maltotriose from starch.